Group 22 - Black & Decker Alligator Lopper
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Revision as of 10:50, 14 November 2012
- Alexander M.
- Keerthi K.
- Spencer K.
- Allicia G.
- Zachery W.
Black and Decker has revolutionized the tool industry with their Alligator Lopper; a design that is described as a combination of an ordinary chainsaw and the parent lopper. The Alligator Lopper is ideal for tree pruning, clearing brush, storm clean-up, cutting firewood and more, and it is a great alternative to chainsaws, manual loppers, handsaws and clippers.
This innovative tool will make cleaning up the yard less of a chore. The clamping jaws grab and cut in 1 easy motion, and with the 4.5 Amp motor, you'll get fast and powerful performance. After a storm, this device can cut fallen branches into manageable pieces to take to the curb or stack by the fire pit. When manual pruners just won't cut it, you'll appreciate the 4 inch cutting capacity that allows you to not only tidy up the yard, but eliminate large branches that keep the sun from reaching your garden below.
The Alligator Lopper’s jaws offer the ultimate in controlled cutting. The rugged metal guards that cover the jaws protect you from the cutting chain and immediately cover the blades once the cut is complete. The scissor action allows for fast, easy cutting and is great for pruning trees & shrubs.
In our group's attempt to further understand the inner mechanisms of our multi-purpose Alligator Lopper hand tool, we plan to perform reverse engineering and deconstruct the equipment to reveal its moving internal parts and subsystem interactions. Once we obtain the actual product, we can further examine its exterior and make assumptions about its limitations as far as movement, accessibility, and other similar characteristics. However, the bulk of our project requires us to disassemble the product. Based on pictures we have viewed online, we anticipate that we will use a wrench or socket set for the two main exterior bolts, Phillips screwdrivers will be required for the outer housing, and a set of allen wrenches could be of significant use when dismantling the subsystems within the housing. During the deconstruction process, we plan to arrange the disassembled parts in an ordered fashion documenting their purpose and its placement within the product's systems. This will make an easier task of reassembling the product after our dissection. Our group seems to be strong in understanding the technical workings of this piece of equipment based on photographs seemingly due to previous experience with lawn care devices. At least one of us has used a chainsaw a few times in their life so that experience and understanding will come in handy when trying to reverse engineer this product.
Before getting started on each gate, the group gates should be divided into different tasks for which each group member will be responsible for. One person will be assigned as the "Communication Liaison". They will be in charge of making sure everyone is knowledgeable about what is going on and who will do what tasks. There will also be a "Gate Manager" who does the updating to the wiki and final check of the uploaded information. They will work with the "Communication Liaison to make sure everyone is doing their work. The group should outline how they plan on tackling the upcoming gate. Based on group member preference, the actual work will be divided equally among the group. This will allow each member to pursue their own interests in dealing with the project. Revision will be a constant process and the group should meet a few times before the assignment date to make sure everyone is on track in delivering their assigned part of the work. The last few days before the due date the group should meet in its entirety and have a formal review of what has been completed so that it is up to the academic standards of each group member.
The following members can be contacted if there are questions about the group:
Black & Decker is a global marketer and manufacturer of quality products used in and around the home, and it also serves as a major supplier of information systems and services to government and commercial clients worldwide. While developing this particular product, Black and Decker designed the Lopper mainly for the benefits of residential homeowners. These benefits focus on factors of safety, maneuverability, and low cost maintenance.
Global - As mentioned above, the majority of consumers who are likely to obtain this product are residential homeowners. Due to its limited size, the ability to perform in industrial and commercial work environment is not possible; however, it is still useful for small landscaping projects. A majority of the homeowners who purchased the Alligator Lopper find it useful for trimming tree branches, clearing their yard space, and cleaning up any fallen branches that occurred due strong winds and aged trees. It reduces the amount of work and time that a normal trimmer or chainsaw would usually occupy and provides a cleaner cut through branches, reducing any mess. The electric chainsaw is also easier on the ears because they generate much less noise than their gas-operated cousins. The Alligator is rated for a pressure level of 87 Decibels and a noise sound level of 98 Decibels, while a comparable chainsaw is rated for a pressure level of 100.7 Decibels and a sound level of 113 Decibels.
Environmental - Compared to the traditional gas powered chainsaw, the Alligator Lopper reduces the amount of pollutants that are set off into the air. Its use of electric power helps to keep the environment cleaner and the need to dispose of residues minimal. Storing this product is also an ease in times of cold and hot weather. All you have to do is put a guard on the bar, wrap the cord up, and store it anywhere you want. Gas chainsaws have to be cooled down, have their gas and oil drained, then stored in a vertical position in a ventilated area.
Economical - Because the price of gasoline is skyrocketing in today's economy, the Alligator Lopper can save homeowners a significant amount of money. There is no need to waste gasoline and maintenance is affordable. Located on their website is a list of replacement parts ranging from $1.00 to $32.00.
One problem that is avoid in this design is kickback; it refers to when the end of the bar hits something and causes the tool to jerk backwards. The electric design has less power than one that is powered by gas, so there will be a reduced chance of you experiencing kickback while operating the tool.
Blacker and Decker designed this product mainly for home improvement and gardening purposes. It is stated in the instruction manual , "Your Black & Decker Alligator Lopper has been designed for pruning trees and cutting small logs up to 4 inches in diameter... This tool is intended for consumer use only", just for warning purposes to consumers that may attempt to use this tool beyond its work capacity. Because its blade is not exposed like that of a normal chainsaw, the Alligator Lopper cannot be used to cut down a tree; rather it is used for pruning branches and clearing up debris of fallen tree branches. Due the Jaw of the Lopper, this chainsaw can only cut to a limit of 4 inch diameter branches, however it had been reported to cut branches with a maximum diameter of 6 inches.
This version of the product is a corded version that runs off a standard U.S. 120 Volt wall outlet. It contains a 4.5 Amp Motor which is powered through the use of an extension cord. The use of an extension cord is required since the product only comes with a short cord attached to the unit. The fact it requires an outlet to work limits its use to within the reach of a given extension cord originating from the wall outlet. The Alligator also must house some sort of Alternating Current to Direct Current converter since the motor that drives the chainsaw portion is most likely a Direct Current motor.
Ultimately the purpose of this machine is to convert electrical energy in the form of Alternating Current into mechanical energy which is harnessed to cut through trees and branches. Based on an initial viewing of the Alligator from online sources, this is the theorized flow and conversion of energy:
- 1)Electricity flows into the device.
- 2)The Alternating Current is converted into Direct Current.
- 3)Power is supplied to the motor.
- 4)The dual trigger system on the handles are depressed by the user, engaging the motor and clutch in order to run the chainsaw.
- 5)By engaging the clutch, the motor powers the sprocket.
- 6)The sprocket spins the chain around the chain guide allowing the user to saw through whatever is placed between the jaws of the Alligator.
The Alligator lopper can be subdivided into the following
- 2)Trigger Assembly
- 3)Scissor Skeleton
Each of these subsystems can be further subdivided into its member components.
"Chainsaw" This would include the motor, the clutch, the sprocket, the chain guide, and the chain. When the triggers are engaged, the clutch make contact with the motor drive shaft and the sprocket. This in turn spins the sprocket which drives the chain around the chain guide. It is the assumption of this group that this motor is a DC motor which would also mean that an Alternating Current to Direct Current converter would be required to run it.
"Trigger Assembly" This subsystem would be wired into the power cord before it reached the motor. It would include the actual plastic triggers themselves, a spring of some sort in order to keep force on the trigger and provide resistance against the user's grip, and finally the pressure sensitive switch which powers the chainsaw. The user depresses both of the triggers concurrently. This causes the triggers to trip the switch located within the grip. When tripped, the switches allow the motor and clutch to engage and the sprocket spins which powers the chain.
"Scissor Skeleton" This comprises the outer cover of the Alligator. There are two components which are the two different levers. These levers essentially are joined at their center at a pivot point, much like a pair of scissors. One side of the levers are the handles where the Trigger Assembly is located. On the other side of the pivot point the chain saw guards are located which is where the Chainsaw subsystem is housed.
To work the Alligator, the user grasps the device by the handles and presses both triggers. This allows the sprocket to be engaged by the motor which turns the chain. The user then presses the two handles together. This clamps the chain guards down on a target branch which then comes in contact with the chain and is sawed in half.
One of the main selling points of the Alligator is that it is lightweight in comparison to other chainsaws and pole cutters currently on the market. It only weighs in at 6.5 lbs. This is due to not only its lack of a gas engine but also by the materials used to assemble it.
The first material one may recognize at a glance of the Alligator is plastic. The plastic used is most likely Polystyrene, which is a thermoset plastic. This type of plastic is hard and durable while still remaining lightweight. The outer shell of the tool is comprised entirely of plastic, including the handles and trigger system used to operate the Alligator.
The other visible material is metal. The chain guards on either side of the chainsaw appear to be some sort of sheet metal, most likely steel. Using plastic in this position would appear to be the wrong decision since it has the possibility to come into contact with the metal chain. In addition to the guards, the chain guide and the chain itself seem to be made of stainless steel. These components would require durability and strength in its operation, something that other materials might not be able to provide. Furthermore, depending on what kind of chain is put on it, the cutting surfaces might be imbedded with ceramics or even diamond dust depending on what the operator is cutting.
Within the Alligator, I would expect more metal and plastic components. The entire trigger system appears to be made of plastic, besides perhaps the spring used to give the trigger some force to hold it in position. the sprocket and clutch are almost certainly made of metal since they need to withstand the force and torque of the DC motor. The motor itself would be comprised of some sort of magnetic metal and copper wiring in order for a current to be applied to turn the magnet which is connected to the drive shaft.
The way in which these components were made is still somewhat unknown. The plastics were most likely molded into their current shape. The metal components could have been formed in three ways: A) They were molded, B) They were stamped, C) They were milled. Based on the price and the intricacies, we do not believe they were milled. The alligator is too cheap to have milled parts since that is usually expensive. The sprocket, components of the chain, and the clutch were most likely molded out of molten metal. The chain guide and guards were most likely stamped out of one large piece of sheet metal and bended and cut into their current forms.
User Interaction Profile
In order for the Alligator to be of any use, the user must interact with the product. To use the product, the user must grasp it by the two protruding handles. They must then compress both of the triggers located in the handles in order for the chain to engage. Using the same general motion as a large pair of scissors, the user the press the handles together in order to close the jaws. This action brings the spinning blade into contact with the object that is to be cut.
The Alligator is pretty easy to use and based on both the trigger placement and past experiences, any user can pick it up and be effective with it almost immediately. It applies the same concept as a pair of scissors: two levers that must be compressed together in order to bring a cutting surface into contact with the intended target. In addition, the triggers are large and very noticeable. They are placed directly in the preferred gripping location making them very hard to ignore. It is also easy to infer that they must be depressed in order to activate the chainsaw blade.
The only problem which might arise is if someone is not able to manipulate the 6.5 lb product. This is why the intended consumer is not the elderly or children, but homeowners and property owners. According the Amazon reviews, the average rating is about 4.5 stars out of 5 based on 403 customer reviews 
Regular Maintenance is required in order to keep the Alligator operational. The user manual suggests that for every 10 minutes of continuous use the chain be lubricated with oil. The product has an oil reservoir which must be filled through the 'Oil Filling Hole'. An excessive amount of oil drips onto the chain bar and keeps it thoroughly lubricated. If the chain dulls due to continued use, the owner may also want to change out the chain. The user guide has a step by step instructional guide on how to take apart and replace the chain, which requires very little work. Finally, the user may have to adjust the tension on the chain so that it is not too loose. This involves loosening two nuts and allowing the chain tensioning device to adjust the tension to the correct amount. The user then just has to tighten the two nuts that he/she loosened and it is ready to go.
Product Alternative Profile
The Alligator Lopper emerged in a market that already had current solutions to hedge trimming and branch clearing. The main types of competing products can be characterized by one of the four following products:
- The chainsaw is the most generic yard tool when considering branch removal. These are usually gas powered with a two stroke engine, which requires a mixture of oil and gasoline as its fuel. Since the power source is contained within the product itself, it is highly mobile and can be operated anywhere as long as fuel is present. The bar length of the Husqvarna 240 is 13 to 16 inches. It has a 2 horsepower engine and weighs 10.3 pounds which is one and a half times as heavy as the Alligator. The weight therefore makes it somewhat cumbersome and hard to control when compared to the Alligator.
- This particular chainsaw costs $209, making it the priciest alternative.
- This type of yard tool can be both battery powered and corded, similar to the different versions of the Alligator Lopper. Its advantage lies in its ability to reach high branches and trim them. This particular pole cutter is 9 feet long meaning it can be used to reach branches 12-14 feet above the ground (9 feet plus height off the ground the person is holding it). This version is battery powered so it is not tethered to a wall socket like the Alligator is. It has a 10 inch chain and bar and different angles which the head can be set at. Its disadvantage lies in cutting things close to the ground such as fallen tree branches. Its 9 foot length also makes it cumbersome to maneuver.
- This particular pole cutter costs $115.
3)Manual Branch Cutters 
- Sample Product: Fiskars 9154 PowerGear 32-Inch Bypass Lopper
- This is the most simple and the cheapest alternative to the Alligator Lopper. It is a manually operated branch cutter With a 2 inch cutting capacity, which is half as large as the cutting capacity of the Alligator. It requires no fuel nor electricity. Its main disadvantage lies in the fact that it relies upon the strength of the user to cut through a branch. This cutter is 32 inches long, which is the average length of a pair of branch cutters.
- This particular pole cutter costs $33, making it the cheapest alternative.
The Alligator Lopper has a another design that is ultimately the same, however its possesses a different power source in the form of a rechargeable battery. The following bullets represent a basic comparison between the Cordless and the Corded Alligator Lopper Models:
- •Cordless has a battery allowing greater mobility while the Corded version is restricted by the length of the extension cord it is plugged into.
- •Cordless has chain brake.
- •Corded an 8 inch chain size compared to the Cordless which has an 6 inch chain size.
- •Both the Corded and the Cordless are rated by Black and Decker for a 4 inch cutting capacity but it has been reported the Corded version has a 6 inch cutting capacity.
- •Corded has an overall length of 25.15 inches while the Cordless has a length of 24 inches.
- •The Corded version weighs 6.5 pounds while the cordless weighs 7.9 pounds.
The cordless Lopper includes:
- 18V Battery
- Battery Charger
- Oil Bottle, Bar, and Chain
The corded Lopper includes:
- Oil bottle
The Alligator Lopper has a fairly straightforward which effectively ties in three main subsystems which are the Chainsaw Subsystem, the Trigger Assembly subsystem, and the Scissor Action Subsystem. Both the Scissor and the Trigger Assembly Subsystems were relatively easy to deconstruct. This assessment is based on the locations of bolts that need to be removed and also the types of tools required by the bolts in order to dissect the subsystem.
Below this are a number of different subsections regarding the dissection of the Alligator Lopper and its component and subsystem interactions. They appear in the following order:
Difficulty Rating System: A three point system was implemented in order to rate and understand the difficulty involved with dissecting the product. Each step is rated based on this scale and an overall rating of difficulty will be assigned to each of the three groupings of components.
Dissection: Outer Cover/Handles: Provided are step by step instructions with visual aides in order to facilitate the diss-assembly process of the Alligator Lopper by a different user. The Outer Cover/Handles are the first thing that that must be taken apart in order to reach the motor mount, motor, and chain system.
Ease of Dissection Analysis: Outer Cover/Handles: This section will address how the difficulty for the Outer Cover/Handles was determined and the factors which determined what the intended difficulty was supposed to be.
Dissection: Chain Guard and Chain Guard Cover: Provided are step by step instructions with visual aides in order to facilitate the diss-assembly process of the Alligator Lopper by a different user. The Chain Guard and Chain Guard Cover may be removed first if the goal of the user is to just gain access to the chain. However it is placed as the second general group of components to be removed since our overall goal was to completely dissect the Alligator Lopper, not to just gain access to the chain.
Ease of Dissection Analysis: Chain Guard and Chain Guard Cover: This section will address how the difficulty for the Chain Guard and Chain Guard Cover was determined and the factors which determined what the intended difficulty was supposed to be.
Dissection: Internal Motor Mount and Motor: Provided are step by step instructions with visual aides in order to facilitate the diss-assembly process of the Alligator Lopper by a different user. This last group of components in the dissection process can be disassembled as far as separating the magnet and coil of the motor. This yields the smallest components our dissection can produce without causing permanent damage to those components.
Ease of Dissection Analysis: Internal Motor Mount and Motor: This section will address how the difficulty for the Outer Cover/Handles was determined and the factors which determined what the intended difficulty was supposed to be.
Difficulty Rating System
1 - Parts or components can be removed from their housings or corresponding components without further use of tools not included with the Alligator Lopper. The user only needs the provided tool to preform the step or requires no tool to preform the step.
2 - Some components must be removed in order to access the desired component. Common tools such as a Flat or Philips head screwdrivers or an Allen wrenches are required to complete the step.
3 - The desired component is located below multiple parts or subsystems. It cannot be accessed or removed without first removing the parts or subsystems obstructing it. Less common tools, such as a Torque screwdriver, are required to complete the step.
Dissection: Outer Cover/Handles
|Step Number||Step||Difficulty Rating||Image|
|1||Start by orienting the Alligator lopper so that it lies on its side with the motor sticking up. This will allow for access to the screws holding the cover together and also to the motor and its housing||1|
|2||Remove two Allen head bolts in the orange cover surrounding the motor’s base. Once removed, this small, half circle shaped cover will easily slide off, revealing the spring that keeps tension on the handles so that they remain closed.||2|
|3||Remove the four Philips bolts from the very top of the motor cover. Remove the top motor cover from the motor.||2|
|4||With the Alligator positioned so that the missing cover is facing the user, remove the 6 Philips heads screws from the far sided handle.||2|
|5||Once removed, lift the outer cover of the handle upwards. Once free of its top half, the trigger system is revealed within the handle. It is composed of a black trigger, two small springs positioned above each end of the trigger, and a switch above the middle of the trigger||1|
|6||Gently pull upwards on the trigger. This will free the springs from compression, so make sure they do not become airborne and lost. Store the springs and the trigger in a safe place where it will not become lost||1|
|7||Pull upwards on the switch so that it will become freed from the two orange plastic pegs it is anchored with.||1|
|8||With the trigger assembly removed from the handle, pull up on the last half of the shell. This completely removes it from the Alligator Lopper, revealing a gear which interlocks with teeth on the cover used to open and close the jaw.||1|
|9||Remove the spring in its trench besides the motor cover and store in a safe location.||2|
|10||On the second handle, there is a small panel held in place by a single Philips head bolt. Remove this bolt along with the small panel it holds.||2|
|11||Next, remove the remaining 10 Philips screws from the orange cover that makes up both the handle and the cover around the motor mount.||2|
|12||Pulling upwards on the cover will separate it from its bottom half revealing the second trigger assembly.||1|
|13||Gently pull upwards on the trigger. This will free the springs from compression, so make sure they do not become airborne and lost. Store the springs and the trigger in a safe place where it will not become lost||1|
|14||Located next to the trigger is the cord which supplies the motor with electricity. It is held in place by two Philips head bolts. Remove the bolts so that the cord can come free from the lower half of the handles.||2|
|15||Two wires lead from the large black cord: a small white one and a small black one. They enter a small white contact box which connects it with the wires that run within the lopper and they are held by two small Flathead screws within the contact box. Loosen these flathead screws until the wires are able to slip free. Store the black cord in a safe location.||2|
|16||Pull upwards on the switch so that it will become freed from the two orange plastic pegs it is anchored with. This will allow the switch to become separated from the lower half of the handles.||1|
Ease of Dissection Analysis: Outer Cover/Handles
Average Difficulty Rating of Dis-assembly: 1.5
Based on the both the difficulty ratings we assigned to each step and also the replacement parts available online, this part of the dis-assembly was intended to occur by the designers. All of the screws and bolts that were removed were removed by common Philips head screwdrivers and Allen wrenches. These types of tools are usually in the possession of the target consumer for the Alligator Lopper. In addition these screws and bolts were easily accessible either outright or with the removal of one additional component.
The following parts may be purchased as replacements for the Outer Cover/Handles:
Gear for the Rotating Jaw
In order to gain access to the parts provided online as replacements, the outer handles of the Alligator Lopper must be removed. All of the screws used to hold the cover in place were located right on the surface of the handles and were accessible without removing multiple components. The ease with which they can be accessed is a sign that it was designed with possible part maintenance or replacement in mind further along in the product life cycle. Furthermore, the tools required to remove these screws were a standard Philips head screwdriver, a standard Flat head screw driver, and and Allen wrench.
|Required Tool||Steps Requiring Tool||Total Screws Removed with tool|
|Philips Head Screwdriver||3,4,10,11,14||22|
These three tools are most likely to be in the possession of the intended consumer. If they are using the Alligator Lopper to do yard work, chances are very high they also own common screwdrivers and Allen wrenches.
Based on the replacement components available and also the ease with which this section may be disassembled, the assumption is that the designers of this product did intend their consumer to take apart this portion of the product to preform maintenance on the Alligator Lopper
Dissection: Chain Guard and Chain Guard Cover
|Step Number||Step||Difficulty Rating||Image|
|1||Flip the Alligator Lopper over so that it rests on the motor||1|
|2||Using the wrench provided with the tool, loosen the two bolts located in the center of the black cover at the beginning of the jaw. When removed, pull off the black cover exposing the chain, sprocket, jaw, and the chain guide.||1|
|3||Locate the rotating jaw with the teeth. It is held together with three Allen headed bolts. Once removed, lift the half side of the jaw up and separate it from the lower half.||2|
|4||The bottom half pivots on a bolt held together by a nut recessed into the lower half of the jaw. Using an Allen wrench, remove the bolt. Pull the lower part of the jaw off the bottom cover.||2|
|5||Located at the bottom of the chain guide is a small plastic clip. This is used to hold the chain guide close to the frame when the two major bolts are removed. Pushing the plastic clip away from the guide towards the sprocket allows the operator to remove the chain, chain guide and sprocket.||2|
|6||Once that is removed, the operator can lift the last plastic cover off of the motor, motor mount, and gear mount.||1|
|7||Underneath this cover is the plastic clip that holds the chain guide in place. With it are two tensions springs that keep the clip compressed against the chain guide resisting slip.||1|
|8||Remove the clip and two springs being careful not to lose them||1|
Ease of Dissection Analysis: Chain Guard and Chain Guide Cover
Average Difficulty Rating of Dis-assembly: 1.38
This overall difficulty rating reflects the type of tools that were required to dissect this section, the location of the screws and nuts required to take it apart, and also how intuitive the whole dissection process was. Based on these factors the only conclusion that is drawn is that the design process was intended to make these the easiest components to remove.
The following is a list of replacement parts sold online for the Chain Guard and Chain Guide Cover:
Chain Bar/Chain Guide
These components are sought after the most since the chain and chain guard area experience the most stress during the product life cycle. Replacement chains are very easy to come by and relatively inexpensive ($23.89) since the lifetime of the chain is much shorter than the lifetime of the whole tool. It thus seems fitting to grant easy access to these parts in the inevitable event that the operator is required to replace it.
The tools required to remove this part of the product are as simply and common as the tools required in he Outer Handles/Cover disassembly. The only required tools are two different Allen wrenches and the wrench that was provided with the Alligator Lopper. This again is a testament to the intentions of the designers to make this part of the product as easy to take apart as possible. The fact that a wrench was included in the box the product came in means that even if the user had no access to any other tools, they still could gain access tot he chain assembly area. The number of bolts required to remove the outer cover also shows the cover was meant to be removed. Only two nuts secured to bolts holds the cover over the chain. By using the provided wrench, the user can have to cover off very quickly in order to service a worn out or faulty component.
|Required Tool||Steps Requiring Tool||Total Screws/Nuts Removed with tool|
|Allen Wrench #1||3||3|
|Allen Wrench #2||4||1|
Once again the Allen wrenches are most likely going to be in the possession of the consumer at the time of purchasing the Alligator Lopper and maintenance.
Averaging the difficulty rating of all the steps together gave an over difficulty rating of 1.38. This value is comparable to the average difficulty of the Outer Cover/Handles which was 1.5. This is reflected by what dissecting these groups of components reveal. Taking apart the Chain Guard and Chain Guide Cover gives the user access to the chain, sprocket, and chain guide. It makes sense that the Alligator Lopper would be designed so that the user can quickly and easily access the chain since this is the area that would experience the most wear and tear.
Dissection: Internal Motor Mount and Motor
|Step Number||Step||Difficulty Rating|
|1||Using a Philips screw driver and a torque screw driver, remove the two torque headed bolts and the one Philips head bolt.||3|
|2||Pull the metal internal motor mount to apart into two pieces.||2|
|3||Within the motor mount is a large gear with a drive shaft connected to a small gear on the drive shaft of the motor. In addition, the two main bolts that hold the chain guides, jaws, and outer covers together are sandwiched between the two sides of the internal motor mount. Remove these bolts and place in a safe place||2|
|4||Pulling on the drive shaft of the larger gear, remove the large gear from its housing||1|
|5||Unscrew the four Philips head screws located on the side of the motor cover. The screws were difficult to remove which leads us to believe they were with an adhesive to prevent removal and access to the internal workings of the motor.||3|
|6||Remove the long plastic motor wire retainer.||2|
|7||Once removed, pull apart the sides of the motor cover.||2|
|8||Inside is the coil and magnet. The magnet can be pulled out of the center of the coil.||3|
Ease of Dissection Analysis: Internal Motor Mount and Motor
Average Difficulty Rating of Dis-assembly: 2.25
With a difficulty Rating of 2.25, this is the hardest portion of the Alligator Lopper to dissect. This is due in part to the tools required to preform the dissection, the strength it took to actually separate some of the components, and the relative complexity of the components that were revealed.
Once opened fully, we discovered there was a gear exchange within the Internal Motor Mount. The drive shaft of the motor was fitted with a gear with a very small radius. this spun a larger gear which had a very large radius. The explanation for this gear exchange is explained with the following equation:
Torque = Radius x Force
Since the force translated from the small gear is going to equal the force translated to the big gear, and the radius of the gears increases, the overall torque produced by the motor is increased by the gear exchange. This gear was smothered in a green lubricant within its housing to make sure that it spins freely while the motor is operating. One of the risks taken by taking apart the motor mount is that dirt can clog the gear housing making the gear difficult to spin.
By taking apart the motor, there is the risk that damage could be done to its internal components. This would cut short the lifetime of the product since the motor is powerhouse in this product. It was discovered however that one can purchase a replacement brush assembly for the motor. The work required to get to the brush assembly seems more costly and timely to the average consumer than just buying a new product. This is partly due to the preventative measure put in place to discourage the dissection of this part.
The measures we noticed that were put in place were the introduction of torque screws and the possible use of adhesive in assembling the motor cover. When taking apart the Internal Motor Mount, there were two torque screws used to keep the mount together. Torque head screwdrivers are not normally included in the collection of tools an average homeowner has at their disposal. This measure is trying to deter the user from dissecting the mount and thereby gain access to the gear housing. Furthermore, the screws used to hold the two halves of the motor cover together were extremely tight. It took a lot of force to unscrew them in comparison to the force required by other screws in the dissection process. This may due to two different things; either the screws were tightened very hard in assembly or they were installed in addition to some sort of adhesive.
|Required Tool||Steps Requiring Tool||Total Screws Removed with tool|
|Philips Head Screwdriver||1,5||6|
|Torque Head Screwdriver||1||2|
Giving the user the option to replace a brush assembly seems to be only useful to those who have the proper amount of time and tools required to fully dissect the Alligator Lopper. The difficulties encountered taking apart the internal motor mount and motor seem to provide evidence that it was not meant to be opened on a regular basis for servicing or maintenance. Due to the complexity of the tools required to dissect it in conjunction with the methods used to install the motor cover around the motor the conclusion is made that the average user is not meant to open this part of the Alligator Lopper up.
Subsystem Interaction Diagram
Subsystem Interaction Analysis
• The first level diagram depict that the trigger requires human input in order to engage the motor of the chainsaw. In the second level diagram, it is detailed that the dual trigger system allows the machine to function when both triggers are simultaneously pressed. The triggers trip a switch , which allows the electricity to flow from the source to the motor itself.
• After the trigger is pressed, electrical energy is transferred from the electrical source, which is provided through the cord, into the motor allowing it to spin in order to produce rotational mechanical energy. The energy produced by the motor is then transferred to the drive assembly (which consists of the clutch and sprocket) increasing the torque due to the internal gear exchange. In turn, the mechanical energy from the sprocket's teeth interaction with chain is engages the rotational motion of the chainsaw producing electrical work out.
Note: The First Level Subsystems diagram shows that the trigger and the motor work in parallel ensuring the two must operate simultaneously in order to proceed to the final step of the overall performance procedure.
3) Human Interaction The final piece to the system is the chainsaws interaction with the cutting material. In order for this to occur, there is a need for pressure to be applied to the handles of the chainsaw as well as mechanical energy from the chain. The mechanical energy is then turned into energy used to shear the material. In the end, it is visibly clear that the material is being cut.
Note: The First Level Subsystems diagram shows that the trigger and the motor work in series with the point at which the material and chainsaw make contact.
The subsystems for the lopper have been arranged in a manner that seems fitting and logical based on user interaction. Initially, the user applies the pulling force to expose the cutting surface, while simultaneously bringing the cutting object into contact with the surface. It is important that these two subsystems are together because of the safety precautions. The user must apply a force to expose the blade, and any mishap from the user would result in the cutting edge to be immediately covered up by the guard. The user input for the triggers is important as well because it is a dual switch that requires both triggers to be pressed at the same time. This is yet another safety feature that aids the user. What is equally as important, is how the electrical signal that is sent from the triggers to the motor is almost instantaneous. The need for consistency with the motor enables user satisfaction and security. It would be detrimental for the user to have unexpected problems in mid cut.
There are methods as to how the subsystems are implemented within the final product. There are imposing factors that give reason to how and why the subsystems are set up and designed the way they are. Globally, the overall use of the electric motor is dependent on the ease of access to a source of household or public power. Clearly, the environmental factors that influence the subsystem of the motor is the use of electricity as a zero emission source of power as opposed to a gasoline powered engine. Socially, it is more logical, knowing the product will be used in residential areas, to use the distinctly quieter motor (a full 15 dB). There is the noticeable economic trade off where the combination of electrical and human subsystems adds the benefits of simplicity and low maintenance, but gives up the power and strength of a gasoline powered chainsaw.
These subsystems all contribute to the overall performance of the lopper. The primary focus being user safety, is addressed by the dual motor triggers located on the handles. This requires the user to have full control over the tool before operating the motor. The connection between the power-drive and the revolving chain is crucial to the performance of the product as well. The motor must be able to supply enough torque through the intermediate clutch and transfer it through to the chain. The use of a successful gear ratio is the driving component behind this process.
Understanding the placement of each subsystem allows us to gather knowledge about how production methods and demand have influenced the final product. Beginning with the simplest, the triggers on the handles simply allows for safety, comfort, and functionality. The wiring from these triggers can add to the diversity of location for the rest of the systems. Having the motor, sprocket, and chain track all in the same arm gives added simplicity to the scissor pivot motion that construction of the product suggests.
Certain Factors Influencing the Subsystem Connections
- Unlike traditional chainsaws, it is clear that the Black and Decker Alligator Lopper was designed to be used by both men and women rather than just by men. The electric switch triggers used to signal the electric motor are very easy to depress. The small electric motor is also a lot lighter than a traditional gas powered motor, which allows the Lopper to lower its weight considerably in comparison with a normal chainsaw.
- The electric motor and smaller chain/bar assembly also allows the Lopper to cut material much more quietly than a traditional chainsaw. Between the loud gas motor and large cutting edge for a normal chainsaw, they often emit sound levels that are comparable to most heavy commercial power tools. All together interacting subsystems only add up to 98 decibels in the Alligator Lopper due to lowering the output power of the system by using electricity rather than gas power.
- The start up time of the Lopper is almost instantaneous due to the connection between an electric power source and the chainsaw subsystem. Once the power cord is plugged in, all it takes is the squeeze of two triggers and power is instantly transferred to the motor, and in turn mechanically to the chain. This was obviously designed to reduce pre-use leg and arm work such as required in the start up process of a gas powered chainsaw.
- While using an electric motor to transfer the trigger signal and power source into mechanical energy instead of a traditional gas motor, the Lopper cuts back on possible pollutants that other similar tools release into the environment. Black and Decker could easily market this as a way to “think green”.
- The plug in electric power supply and electric motor allow the lopper to be stored easily without much preparation. There is no need to drain any fuel before storing it long term. This differs from the storage process of a gas powered saw. Improper storage could result in a large mess along with possible flooding the engine and ruining it.
- The majority of the component replacement parts are very cheap, most of which can be purchased from the Black and Decker website for under $32. All of the functions between the sub-systems are fairly straight forward to the point where untrained consumers can fix most problems that would arise with the Lopper.
- With the price of gasoline rising with no end in sight, the use of electricity as the main power source for the Lopper greatly reduces costs for the consumer to use the product.
- Each of the components is made up mostly of the same materials including heavy duty plastic and thin steel. This allows the manufacturer to buy these materials in bulk, and therefore at a cheaper rate. This tool was also assembled using a large number of the same screws and fasteners. This allowed the manufacturer to either buy or produce in bulk as well, which would in turn save them production costs. These saving are then passed down to the consumer in the form of a cheap product.
- The lighter-duty nature of this tool allows it to be produced in a much cheaper manner than most other chain saws. While only having to design the Lopper to handle the lighter duties of the average homeowner, the manufacturer can use cheaper components that don’t have to meet commercial/heavy duty specs. Although the electric motor and 4 inch bar on this “saw” can’t match the capabilities of a two-stoke gas powered 16 inch bar saw, this product is considerably less expensive to build/manufacture. The manufacturer can then pass these savings down to the consumer in the form of a cheaper end product.
- When looking at tools designed for the average suburban homeowner, safety is always a huge concern. This can easily be seen in the double-trigger safety system within the trigger sub-system. This forces the operator to keep two hands on the lopper at all times when it is in use, therefore minimizing the risk of injury.
- The handle-jaw subsystem also minimizes risk of injury by only exposing the cutting edge/bar of the lopper only when the operator wants it to be open. The subsystem is also spring loaded to keep the jaws closed.
- The risk of kick-back with this “saw” is greatly reduced due to the lack of power associated with the small electric motor providing power to the chain/bar. The average homeowner, women included, using this tool usually would not be prepared to face or even be strong enough to handle the kick back associated with the average chain saw and this eliminates that need.
- The smaller bar and less powerful electric motor makes the lopper a lot less intimidating to the average consumer than a full-sized chain saw. The smaller cutting edge and the fact that is covered by the jaws of the handle-jaw subsystem makes this tool look a lot safer to use than a normal saw, and in turn most people are a lot less hesitant to use it.
|Component Name||Function||Material||Forming Process||Part Number||Image|
|Gear||This gear is fixed to the free moving jaw of the Lopper. The teeth located on the handle which is allowed to rotate interlocks with the teeth of this gear. When the handles are pulled apart, the teeth on the handle move turning this gear. The gear, which is attached to the jaw, rotates which rotates the jaw open. The gear is held in place to the jaw by a bolt and a lock nut. Only one such gear is used within the product.||High density plastic||Injection Molding||588088-00|
|Wire Housing Cover||This small housing cover is located on the outside of the actual handles. It is held in place by a Philips head screw. Once removed, the user is given access to the connection where the wires running from external cord are joined with the wires used internally within the Alligator Lopper. There is only one wire housing cover used within the entire product||High density plastic||Injection Molding||-|
|Trigger||The trigger is located in between the two sides of each handle. The springs located beneath the trigger and held in place by plastic anchors proved the necessary force to keep the trigger pressed against its housing and away from the switch below it. When the user depresses the trigger, they must counteract the force of the springs. The trigger makes contact with the switch. When both triggers are compressed so that they make contact with their respective switches, the motor is allowed to run and the chain to move. There are two triggers used within the product, each trigger being held by two springs.||Trigger:High density plastic, Spring:Steel Alloy||Trigger:Injection Molding, Spring:Drawing and curling||-|
|Power Cord with Male Electrical Socket||The cord protector is made of high density plastic which serves to protect the male electrical socket. This socket is used to connect the product to its power source through the use of an extension cord. From the Cord Protect runs the Cord Set which is comprised of a copper wire insulated with rubber. The cord set enters the product at the end of a one of the handles and is connected to the internal wiring of the Lopper.||Cord Protector:High density plastic, Cord Set:Copper Wire, Rubber Insulator||Cord Protector:Injection Molding, Cord Set:Drawing of Copper into wire, coating the wire with rubber||Cord Protector:770235-00, Cord Set:588370-00|
|Large Gear||This gear connects the driveshaft of the motor to the sprocket. The gear located on the drive shaft of the motor is very small in comparison with this gear. This gear exchange increases the torque produced by the motor and transfers it to the sprocket which moves the chain. The large gear has its own driveshaft which the sprocket slides onto. Therefore the rotation of the gear causes the rotation of the sprocket and as a result the movement of the chain. This gear sits within the motor mount/gear housing. There is only one of these gears in the product.||Steel||Die Casting||-|
|Sprocket||The sprocket slides onto the shaft which is connected to the large gear. When the large gear spins, the sprocket spins. The teeth of the sprocket make contact with the chain in a fashion that does not permit slipping. When the sprocket is turned, it moves the chain by pulling a link towards it. Tension in the chain, which is circular, means that when one side of the chain is being pulled towards the sprocket, the opposite side is being pulled away from the sprocket. There is only one sprocket in the product.||Steel||Die Casting||587580-00|
|Bar Holding Latch||The two springs are connected to two anchors which sit underneath the outside cover of the Lopper nearest to the chain assembly. This is where the bar sits on the Lopper. The clip portion of the plastic component extended through the cover and over the edge of the bar. The tension springs keep the latch firmly over the bar, holding it snugly against the outside cover. There is only one of these clip/spring components holding the bar against the cover.||Latch: High Density Plastic, Springs:Steel Alloy||Latch: Injection Molding, Springs: Drawing, Coiling of the Wire||-|
|Handle Compression Spring||Located around the motor within the cover of the second handle is a small trench. Within this small trench sit both the teeth of the top handle and this compression spring. When the handles are together, the spring is at its largest allowable length in the trench. It creates a force which pushes the handles together. When the handles are separated, the force of the spring is overcome. As the teeth of the handle rotates into the trench, it makes contact with the teeth of the gear opening the jaw. Meanwhile the spring is fully compressed. Letting go of the handles allows the force of the compressed spring to overcome the force of friction between both the teeth in the handle and the gear, and also the teeth of the handle and the walls of the trench. This forces the handles together and the jaw to close, which is its resting position.||Steel Alloy||Coiling of the Wire||-|