Group 29 - 5 HP IC Motor
(→Disassembly Process) |
(→Disassembly Process) |
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| align="center" |13 | | align="center" |13 | ||
| − | | align="center" | | + | | align="center" |Unscrew eight ½” hexagonal head bolts (part 16) holding head onto engine block (part 37). |
| − | | align="center" | | + | | align="center" |Socket Wrench |
| align="center" |Easy | | align="center" |Easy | ||
|- | |- | ||
| align="center" |14 | | align="center" |14 | ||
| − | | align="center" | | + | | align="center" |After removing screws pull off head (part 17) and head gasket (part 17a) from engine block (part 37). |
| − | | align="center" | | + | | align="center" |By Hand |
| − | | align="center" |Moderately | + | | align="center" |Moderately Easy |
|- | |- | ||
| align="center" |15 | | align="center" |15 | ||
| − | | align="center" | | + | | align="center" |Detach grounding wire from pickup coil (part 18. |
| − | | align="center" | | + | | align="center" |Screw Driver |
| align="center" |Easy | | align="center" |Easy | ||
|- | |- | ||
| align="center" |16 | | align="center" |16 | ||
| − | | align="center" | | + | | align="center" |Unscrew two 5/16” hexagonal head bolts holding on pickup coil (part 18) then remove pickup coil as well as spark plug cord. |
| − | | align="center" | | + | | align="center" |Socket Wrench |
| align="center" |Easy | | align="center" |Easy | ||
|- | |- | ||
| align="center" |17 | | align="center" |17 | ||
| − | | align="center" | | + | | align="center" |Remove pull string catch nut from fly wheel (part 19) using 19mm socket. |
| − | | align="center" | | + | | align="center" |Socket Wrench |
| align="center" |Easy | | align="center" |Easy | ||
|- | |- | ||
| align="center" |18 | | align="center" |18 | ||
| − | | align="center" | | + | | align="center" |Remove fly wheel (part 19). |
| − | | align="center" | | + | | align="center" |Hammer |
| − | | align="center" | | + | | align="center" |Hard |
|- | |- | ||
| align="center" |19 | | align="center" |19 | ||
| − | | align="center" | | + | | align="center" |Unscrew two 5/16” hexagonal head bolts holding on throttle plate, grounding wire and spring (all attached together: part 21). |
| − | | align="center" | | + | | align="center" |Socket Wrench |
| align="center" |Easy | | align="center" |Easy | ||
|- | |- | ||
| align="center" |20 | | align="center" |20 | ||
| − | | align="center" | | + | | align="center" |Unscrew two 5/16” bolts (part 22a) with nuts holding carburetor (part 22) to intake tube (part 23). |
| − | | align="center" | | + | | align="center" |Socket Wrench |
| align="center" |Easy | | align="center" |Easy | ||
|- | |- | ||
| align="center" |21 | | align="center" |21 | ||
| − | | align="center" | | + | | align="center" |Unscrew two hexagonal head bolts (part 23a) holding intake tube and gasket (part 23) to engine block (part 37). |
| − | | align="center" | | + | | align="center" |Socket Wrench |
| align="center" |Easy | | align="center" |Easy | ||
|- | |- | ||
| align="center" |22 | | align="center" |22 | ||
| − | | align="center" | | + | | align="center" |Unscrew two 5/16” hexagonal head bolts (part 24a) then remove valve cover and gasket (part 24). |
| − | | align="center" | | + | | align="center" |Socket Wrench |
| align="center" |Easy | | align="center" |Easy | ||
|- | |- | ||
| align="center" |23 | | align="center" |23 | ||
| − | | align="center" | | + | | align="center" |Remove intake and exhaust valve (part 25), valve spring (part 25a) and valve clip (part 25b). |
| − | | align="center" | | + | | align="center" |Screw Driver |
| align="center" |Easy | | align="center" |Easy | ||
|- | |- | ||
| align="center" |24 | | align="center" |24 | ||
| − | | align="center" | | + | | align="center" |Pry off drive pulley (part 26). |
| − | | align="center" | | + | | align="center" |Hammer and Screw Driver |
| align="center" |Easy | | align="center" |Easy | ||
|- | |- | ||
| align="center" |25 | | align="center" |25 | ||
| − | | align="center" | | + | | align="center" |Remove six 10mm hexagonal head bolts (part 27) from crank case cover (part 29). |
| − | | align="center" | | + | | align="center" |Socket Wrench |
| align="center" |Easy | | align="center" |Easy | ||
|- | |- | ||
| align="center" |26 | | align="center" |26 | ||
| − | | align="center" | | + | | align="center" |Remove crank key (part 28) from crank shaft (part 33). |
| − | | align="center" | | + | | align="center" |Screw Driver |
| align="center" |Easy | | align="center" |Easy | ||
|- | |- | ||
Revision as of 20:43, 3 December 2008
Contents |
Tecumseh 5 HP Engine
Executive Summary
This wiki documents the the three phases of the analysis of a 5 Horsepower Tecumseh engine. This engine was originally used to power a push lawnmower, but the analysis below begins after it had been removed from the mower body, and covers only components of the engine.
The first phase of this project focused on the disassembly and analysis of the motor's condition. It was determined that this motor probably did not run due to a faulty piston ring. During the second phase group members cataloged and analyzed each of the approximately 38 total parts.
The final phase of the project involved reassembling the motor, and reflecting on its overall design. Based on the understanding of the engine during the previous phases recommendations are made regarding the design, manufacturing, use, and life-cycle of the engine.
Introduction
This product was used to run a push mower. It is powered by an internal combustion that is used to spin the blades. Based on the condition of its parts this engine will not run, but this has not been tested.
Group Members:
Ian Kelsey - disassembly, reassembly, wiki creation
Dan Leake - disassembly, wiki creation
Kyle Johnson - disassembly, reassembly
Alex Lovallo - disassembly, reassembly, wiki creation, team leader
Sanket Chavan -
Product Description
- 5 Horsepower Lawnmower Engine
- Manufacturer: Tecumseh
- Model Number:
Before Dissasembly
Purpose and Operation
This 5 HP engine was used to power a pull start lawnmower. It was likely intended for urban or small yard use as it does not seem to have a drive system for its own locomotion. This engine once transformed chemical energy from combustion into linear kinetic energy using its piston. The connecting arm and crankshaft then converted this linear reciprocation motion into translational motion which could be used to power the mower blades directly, or may have been fed to the blades by a belt system.
It is possible that this engine will run as it does seem to have compression when the pull cord is pulled. While it is not possible for us to test this mower these is strong evidence that it will not run, or at least will only run for a short while until it breaks. The muffler of the engine is full of oil that will run out if it is tipped. This indicates that the piston rings may have failed and the engine is burning oil. Failed piston rings result in a lot of sediment build up from the burnt oil as well as increased piston friction which can significantly reduce the life of the engine. If enough heat builds up parts of the engine can melt rendering it inoperable.
Not including any fasteners it seems like that this engine will have roughly 40 parts. Viewing the exterior of the motor it is clear that plastic, and steel or iron have been used. Inside we expect to come across more iron, steel, rubber, and potentially some sort of textile.
Disassembly Process
| Step Number | Process | Tool | Level of Difficulty |
|---|---|---|---|
| 1 | Unscrew (counterclockwise) the gas cap (part 1) from the gas tank (part 8). | By Hand | Easy |
| 2 | Unscrew and remove oil dipstick (part 2) from dipstick tube (part 9). | By Hand | Easy |
| 3 | Remove air filter cap (part 3) from air filter housing (part 6) by unscrewing one phillips head screw. | Screw Driver | Easy |
| 4 | Take out foam air filter and cardboard support (part 4) from air filter housing (part 6). | By Hand | Easy |
| 5 | Unscrew two hexagonal head bolts (part 5) that are attaching the air filter housing (part 6) to the carburetor (part 22), then remove air filter housing. | By Hand | Easy |
| 6 | Unscrew three 8mm hexagonal head bolts (part 7) that are holding the gas tank (part 8) to engine block (part 37), then remove gas tank. | Socket Wrench | Easy |
| 7 | Unscrew one 8mm hexagonal head bolt and remove dipstick tube (part 9) from side of carburetor. | Socket Wrench | Moderately Easy |
| 8 | Unscrew two ¼” hexagonal head bolts (part 10a) then remove pull cord cover (part 10b) and pull cord (part 10). | Socket Wrench | Easy |
| 9 | Unscrew two 3/8” hexagonal head bolts (part 11) as well as two 8mm hexagonal head bolts (part 11a), then remove crank case cover (part 29) from engine block (part 37). | Socket Wrench | Moderately Hard |
| 10 | Removed crank case ventilation tube (part 13) from engine block (part 37). | By Hand | Moderately Easy |
| 11 | Unscrew and remove spark plug (part 14) from engine block using 21mm socket. | Wrench | Moderately Easy |
| 12 | Unscrew two 11mm bolts and remove muffler (part 15) from engine block (part 37). | Socket Wrench | Easy |
| 13 | Unscrew eight ½” hexagonal head bolts (part 16) holding head onto engine block (part 37). | Socket Wrench | Easy |
| 14 | After removing screws pull off head (part 17) and head gasket (part 17a) from engine block (part 37). | By Hand | Moderately Easy |
| 15 | Detach grounding wire from pickup coil (part 18. | Screw Driver | Easy |
| 16 | Unscrew two 5/16” hexagonal head bolts holding on pickup coil (part 18) then remove pickup coil as well as spark plug cord. | Socket Wrench | Easy |
| 17 | Remove pull string catch nut from fly wheel (part 19) using 19mm socket. | Socket Wrench | Easy |
| 18 | Remove fly wheel (part 19). | Hammer | Hard |
| 19 | Unscrew two 5/16” hexagonal head bolts holding on throttle plate, grounding wire and spring (all attached together: part 21). | Socket Wrench | Easy |
| 20 | Unscrew two 5/16” bolts (part 22a) with nuts holding carburetor (part 22) to intake tube (part 23). | Socket Wrench | Easy |
| 21 | Unscrew two hexagonal head bolts (part 23a) holding intake tube and gasket (part 23) to engine block (part 37). | Socket Wrench | Easy |
| 22 | Unscrew two 5/16” hexagonal head bolts (part 24a) then remove valve cover and gasket (part 24). | Socket Wrench | Easy |
| 23 | Remove intake and exhaust valve (part 25), valve spring (part 25a) and valve clip (part 25b). | Screw Driver | Easy |
| 24 | Pry off drive pulley (part 26). | Hammer and Screw Driver | Easy |
| 25 | Remove six 10mm hexagonal head bolts (part 27) from crank case cover (part 29). | Socket Wrench | Easy |
| 26 | Remove crank key (part 28) from crank shaft (part 33). | Screw Driver | Easy |
| 27 | Removed Washer off of Gear from Metal Gear | By Hand | Easy |
| 28 | Removed Cylindrical Slider from Linear Oscillator | By Hand | Easy |
| 29 | Removed Blade Changing Piece from Blade Changing Component | By Hand | Difficult |
| 30 | Removed Blade Changing Spring from Blade Changing Component | By Hand | Easy |
| 31 | Removed Allen Wrench Screw from Blade Changing Component | 3/32 Allen Wrench | Easy |
| 32 | Removed Blade Changing Component from Linear Oscillator | By Hand | Easy |
| 33 | Removed Felt Piece from Linear Oscillator | By Hand | Easy |
| 34 | Removed Cylindrical Slider 2 from Linear Oscillator | By Hand | Easy |
After Disassembly
Component List
| Part # | Component Name | Quanity | Material(s) | Manufacturing Process | Description of Function | Image | Physical Description |
|---|---|---|---|---|---|---|---|
| 1 | Gas Cap | 1 | Plastic | Injection Molded | To seal the gas tank, by means of interior threading and a rubber gasket, to prevent leakage but yet allow air to pass into the tank to allow the free flow of gas out of tank |  |
Red Colored. Round with vertical ribs for grip, interior threading. Contains interior rubber ring to create seal |
| 2 | Oil dipstick | 1 | Plastic, Steel | Injection Molded, Stamped | Used to check oil level in engine |  |
Long steel stick with round plastic cap |
| 3 | Air filter cap | 1 | Plastic | Injection Molded | Holds air filter into place on engine block |  |
Plain top surface and the lower surface has ribs to secure the air filter |
| 4 | Air filter | 2 | Foam, Cardboard | Chemicals are mixed then a gas in pumped in to create air bubbles | Filters air coming into engine |  |
Main filter made of foam with a cardboard support |
| 5 | Hex-head bolts | 2 | Steel | Rolled steel stock then stamped head to shape | Holds air filter and cover into place |  |
Cylindrical with threads and hex shaped head |
| 6 | Air filter housing | 1 | Plastic | Injection Molded | Houses air filter. Allows the air from the surroundings to enter and lets filtered air flow to the carburetor |  |
Rectangular with an inlet pipe on one end and an outlet at the other |
| 7 | Hex-head bolts 8mm | 3 | Steel | Rolled steel stock then stamped head to shape | Holds gas tank onto engine block |  |
Cylindrical with threads and hex shaped head |
| 8 | Gas tank | 1 | Plastic | Injection Molded | Holds gas |  |
Tank is plastic and is molded to fit side of motor and is flat on other side |
| 9 | Dip stick tube | 1 | Plastic | Injection Molded | Allows access for dipstick to travel into the crank case to check oil level |  |
Funnel-like at the top with an extended pipe |
| 10 | Pull cord with handle | 1 | Nylon cord with plastic handle | Nylon- Thin composite that is weaved into cord, Plastic- Injection molded | Used to manually start the engine by rotating a pulley which in return rotates the crankshaft and initiating the combustion process |  |
Durable nylon fiber cord that winds around the pulley with a plastic handle at other end |
| 10a | Hex-head bolts | 2 | Steel | Nylon- Thin composite that is weaved into cord. Plastic- Injection molded | Holds pull cord cover on |  |
Cylindrical with threads and hex shaped head |
| 10b | Pull cord assembly | 1 | Steel and plastic | Housing is stamped steel, plastic pulley is injection molded, and engagement mechanism is stamped and die cast | Transfers energy from pull cord to crankshaft | |
Circular cover made of steel with striations, an inner pulley made of plastic, and a spring loaded metal engagement mechanism |
| 11 | Hex-head bolts 3/8" | 2 | Steel | Rolled steel stock then stamped head to shape | Holds on fly wheel cover | |
Cylindrical with threads and hex shaped head |
| 11a | Hex-head bolts 8mm | 2 | Steel | Rolled steel stock then stamped head to shape | Holds on fly wheel cover |  |
Cylindrical with threads and hex shaped head |
| 12 | Metal fly wheel cover | 1 | Steel | Sheet metal stamped into form, as well as holes punched into top | Protects user from moving fly wheel as well as allows for ventilation |  |
Steel sheet metal with holes to allow for air flow |
| 13 | Crank case ventilation tube | 1 | Rubber | Extruded through a die and then cut into sections | Allows oil vapor and pressure from crank case to be vented to the air filter to be sent through the combustion process |  |
Rubber hose |
| 14 | Spark plug | 1 | Ceramic, copper, aluminum, glass | Assembled from variety of manufactured components | Creates spark to initiate combustion |  |
Physical: cylindrical, hex shaped at base. Threaded at one end. Ceramic Coating over portion. One end has electrical connection to plug, the other end has electrodes to produce sparks |
| 15 | Muffler with two 11 mm bolts | 1 | Steel, muffler is two separate pieces welded together | 2 pressed pieces of sheet metal, extruded steel rods then thread rolling | The muffler reduces engine noise by creating a resonating chamber |  |
Silver color, inlet pipe on one side, small outlet holes on other side |
| 16 | 1/2" hex-head bolts | 8 | Steel | Extruded steel rods then thread rolling | Use threading to secure engine components together |  |
Black, small threads for metal use, hex shaped drive hole |
| 17 | Head | 1 | Cast iron | Die-cast then machined | Radiates heat from engine, seals combustion chamber. Has 8 holes to attach to head, 1 hole to allow spark plug, and 2 small holes to attach an external component |  |
Square plate with parallel fins. 11 holes |
| 17a | Head Gasket | 1 | Aluminum | Layered punched aluminum | Creates a seal between the head and the engine block. |  |
Flat, square with holes for bolts |
| 18 | Pick-up coil with rubber housed cord | 1 | Steel, rubber | Thin pieces or sheet metal that are rolled, vulcanized rubber process to create hose. Spray coated with sealant afterwards | Produces high voltage output pulses for firing the associated spark plug |  |
U-shaped bracket surrounding a black cube. Both have layered steel in the ends. Spark plug wire comes from rear. Small strip for attaching grounding wire. Has plastic spray coating to seal the back side |
| 19 | Nut, washer and pull string catch | 1 | Steel | Stamped and machined steel.washers are stamped from sheet metal, nuts are extruded then cut and bored out | Teeth on interior cause rotation of crank when pull string is pulled to start motor. |  |
cup shaped steel piece. With teeth on inside. Hole in top center for affixing bolt |
| 20 | Fly wheel | 1 | Cast iron | Die-cast then machined down to specs | Rotates mounted magnet past pickup coil creating alternating magnetic field inducing current |  |
Round in shape, has vertical fins, magnet on one side, counter balance on other |
| 21 | Two 5/16" bolts and washers, throttle control and grounding wire | 1 | Steel, copper wire | Throttle components stamped from sheet metal and bent. extruded steel rods then thread rolling, washers stamped from sheet metal, copper wire extruded | Throttle connected to butterfly valve to control gas input to combustion chamber. Throttle cable holds throttle open while in operation. When the cable is not under tension the throttle closes because of attached spring breaking the electrical connection to pick up coil. Preventing spark stopping engine |  |
Flat plate with hinge and spring to throttle control and grounding wire |
| 22 | Carburetor | 1 | Cast iron, steel , rubber | Portion is die cast iron, stamped steel, extruded rubber | Carburetor controls mixture of gasoline and air flowing to the combustion chamber. Cylidrical shape filters the gasoline before combustion |  |
Cylindrical with rubber primer on side. One input for gas, two holes for air flow. Throttle butterfly valve on interior. Wire arm attached to throttle |
| 22a | Nuts and bolts | 2 | Steel | Extruded steel rods then thread rolling, nuts extruded then cut and bored | Holds carburetor into place |  |
5/16" |
| 22b | Gas line | 1 | Rubber gas line | Extruded rubber hose | Provides a path for gas to flow from tank to carburetor |  |
Rubber hose |
| 23 | Intake tube with gasket | 1 | Cast Iron | Die cast Iron | Transports the air from the carburetor into the engine. Gasket prevents leakage in joint between tube and carburetor |  |
L shaped tube, with 2 bolt flanges on each end. Gasket matches flange shape |
| 23a | 3/8" bolts with washers | 2 | Steel | Extruded steel rods that are thread rolled, washers are punched out | Fasten intake tube to carburetor and engine block |  |
Bolts |
| 24 | Valve cover, valve gasket | 1 | Steel bolts, steel cover with plastic gasket | Stamped steel and stamped plastic | Seals valve train |  |
Steel cover, plastic gasket |
| 24a | 5/16" bolts | 2 | Steel | Extruded steel rods that are thread rolled | Holds valve cover to engine block |  |
Bolts |
| 25 | Valve | 2 | Steel | Machined from solid stock | One valve controls air/fuel intake into combustion chamber. Second valve controls exhaust out of chambers |  |
Long cylinder and thing with flattened head. Filleted near head |
| 25a | Valve spring | 2 | Steel | Coiled, hot wound, and hardened in form | Holds valves shut until proper time |  |
Spring |
| 25b | Valve spring clip | 2 | Steel | Punched | Secures spring to valve |  |
Two diameters of ring on top of each other. Smaller diameter can fit inside of spring. Has slot in middle for valve stem to slip into |
| 26 | drive pulley | 1 | Steel | Machined | Connects to crank shaft to use engine power to drive belt |  |
Hollow cylinder with groove around outside edge and key way through inside |
| 27 | 10 mm bolts with washers | 6 | Steel | Extruded steel rods that are thread rolled | Attached crank case to the motor block |  |
Bolts |
| 28 | Key from crank shaft | 1 | Steel | Stamped | Hold drive pulley in line with crank shaft so they rotate together |  |
Small half cylinder cut along long axis |
| 28a | Crank case pins | 2 | Steel | Cut steel bar | Align crank case bolts holes with the blocks bolt holes |  |
Short cylinders with rounded ends |
| 29 | Crank case cover | 1 | Cast iron | Die cast iron then machined | Holds parts and oil inside crank case. |  |
Rounded shape with holes to affix to crank case, holes for aligning pins, holes in center for crank shaft. Interior cavity to hold and align camshaft and camshaft aligner |
| 30 | Cam shaft | 1 | Cast iron | Die-cast then machined | Powered by crank shaft, has gear and lobes sized to open and close valves at proper time |  |
Shaft with two lobes, a central gear, smooth and cylindrical on both ends |
| 31 | Valve lifters | 2 | Steel | Welded and Machined Steel | Are pushed up by lobes of cam shaft. When pushed up they open the valves in the combustion chamber |  |
Flat plate with cylindrical shaft attached |
| 32 | Connecting rod cap | 1 | Cast aluminum | Cast and then machined | Holds the connecting rod to the crank shaft |  |
Semi-circular curved bar with a bolt hole on either end. Inner surface is machined . Inside of surface is machined to reduce friction |
| 32a | 1/4" hex-head bolts | 2 | Steel | Extruded steel rods that are thread rolled | Fasten connecting rod cap to connecting rod over crankshaft |  |
Bolts |
| 33 | Crank shaft | 1 | Cast iron with machined parts | Cast and then machined to specifications | Translates reciprocating linear piston motion into rotation |  |
Cylindrical shaft with an offset cylinder in the middle, has two counter weights near middle |
| 33a | Washer | 1 | Steel | Punched | To reduce friction on the crankshaft |  |
Flat round ring made of steel |
| 34 | Connecting rod | 1 | Cast aluminum | Cast the machined | Connects the piston to the crankshaft transmitting the power |  |
I shaped bar with circular hole on one end and semicircular groove on the other end that mirror the shaped of the connecting rod cap. Has a bolt hole on either side of the semi circular end to interface with the connecting rod |
| 35 | Wrist or gudgeon pin with a clip | 1 | Steel | Pin is machined from solid stock, Clip is shaped and heated to hold form. | Connects the piston to the connecting rod and provides a bearing for the connecting rod to pivot as it moves |  |
Tube is a bored out cylinder and clip is shaped like a lowercase e |
| 36 | Piston | 1 | Aluminum Alloy | Cast and machined to specifications. | Transfers the force from combustion gas in the cylinder to the crankshaft via the connecting rod. Forces exhaust out of exhaust valve and draws the air fuel mixture into the combustion chamber. Compresses the air/fuel mixture pre-combustion |  |
Cylindrical with flat plane on one end. Has lateral hole to allow wrist pin. Has grooves in side for piston rings and a hollowed interior to reduce mass |
| 36a | Piston Rings | 3 | steel and coated steel | Punched steel, One ring has a spring coating along outside edge | Seal the combustion chamber/ Support heat transfer from the piston to the cylinder wall/ Regulate engine oil consumption |  |
Each ring has one gap. One ring is not solid steel but has a composite material insert |
| 37 | Engine block | 1 | Cast iron | Die cast and machined to specifications | Houses all of internal engine parts |  |
Hollowed rectangle with fins |
| 38 | Cam shaft aligner | 1 | Plastic ring with stainless steel rod in it | Machined steel, injection molded plastic | Holds one end of the cam in place to insure that the teeth between the crankshaft gear and camshaft gear align |  |
Plastic ring with extruded tube off one side with a steel insert in it |
CAD Models
Assembly Process
| Step Number | Process | Tool | Level of Difficulty |
|---|---|---|---|
| 1 | Remove 7 Phillips-head screws | Phillips-head Screwdriver | Easy, 1 Screw Quite Difficult |
| 2 | Removed Rip Fence Bolt to Saw Blade Locking Lever | By Hand | Easy |
| 3 | Removed Removed Dust Blower Angle off of Dust Blower | By Hand | Easy |
| 4 | Removed Dust Blower and Rip Fence off of Casing | By Hand | Easy |
| 5 | Removed Rip Fence off of Casing | By Hand | Easy |
| 6 | Removed Plastic Blade Guard off of Casing | By Hand | Easy |
| 7 | Removed Casing off of Casing | Philips-head Screwdriver | Moderately Easy |
| 8 | Removed Gel Max Comfort Grip off of Casing | By Hand | Easy |
| 9 | Removed Shoe Plate Locking Gear off of Casing | By Hand | Easy |
| 10 | Removed Shoe Plate Locking Knob off of Casing | By Hand | Easy |
| 11 | Removed Trigger Switch off of Casing | By Hand | Easy |
| 12 | Removed Lock on Button off of Trigger Switch | By Hand | Easy |
| 13 | Removed Lock Spring off of Lock on Button | Flat-head Screwdriver | Easy |
| 14 | Removed Plastic Lock Washers off of Lock on Button | Flat Head Screwdriver | Moderately Difficult |
| 15 | Removed Switch Breaker off of Trigger Switch | By Hand | Easy |
| 16 | Removed 2 Cord Clamp Screws off of Cord Clamp off of Casing | Phillips-head Screwdriver | Easy |
| 17 | Removed Red Motor Connecting Wire off of Spring Loaded Graphite | By Hand | Easy |
| 18 | Removed Black Motor Connecting Wire from Spring Loaded Graphite | By Hand | Easy |
| 19 | Disassembled Spring Loaded Graphite Internals | By Hand | Easy |
| 20 | Removed Motor Screw From Casing | Philips-head Screwdriver | Easy |
| 21 | Removed Red Motor Connecting Wire From Armature | By Hand | Easy |
| 22 | Removed Black Motor Connecting Wire from Armature | By Hand | Easy |
| 23 | Removed Metal Gear From 1/4in. Plate | By Hand | Easy |
| 24 | Removed 1/4in. Metal Plate from Armature Shaft With Rotar | By Hand | Easy |
| 25 | Removed Small Metal Plate off of Armature Shaft With Rotar | By Hand | Easy |
| 26 | Removed Linear Oscillator from Metal Gear | By Hand | Easy |
| 27 | Removed Washer off of Gear from Metal Gear | By Hand | Easy |
| 28 | Removed Cylindrical Slider from Linear Oscillator | By Hand | Easy |
| 29 | Removed Blade Changing Piece from Blade Changing Component | By Hand | Difficult |
| 30 | Removed Blade Changing Spring from Blade Changing Component | By Hand | Easy |
| 31 | Removed Allen Wrench Screw from Blade Changing Component | 3/32 Allen Wrench | Easy |
| 32 | Removed Blade Changing Component from Linear Oscillator | By Hand | Easy |
| 33 | Removed Felt Piece from Linear Oscillator | By Hand | Easy |
| 34 | Removed Cylindrical Slider 2 from Linear Oscillator | By Hand | Easy |
After Assembly
Engine Operation
This engine was designed as a small 4-stroke engine, which was most likely used to power a push mower. The operation of this product begins initially with the startup. This is done when the operator presses the primer bulb a few times, which causes gas to be forced into the carburetor and also removing any air in the fuel line. The operator then proceeds to manually pull the draw string, which is indirectly attached to the crankshaft by a clutch mechanism. When the clutch is engaged during startup, the crankshaft is forced to rotate, initiating the four stroke cycle. This means that there are four necessary steps or strokes needed to complete a cycle. These four strokes are the intake, compression, power and exhaust. The process begins when air is drawn through the air filter, where it then travels through the intake tube into the carburetor. When the air reaches the carburetor, gas is released through small jets, causing atomization to guarantee a saturated mixture of air and fuel. This mixture is regulated by the carburetor which is dependent upon the users desired operation speed. This is done by using a throttle valve to control the air flow. The mixture is then drawn into the engine through the intake valve during the intake stroke. The intake valve is controlled by the camshaft, which is driven by the crankshaft. The valve opens during the intake stroke, which starts with the piston at top dead center (TDC), meaning that the piston is at a position that is the farthest away from the crankshaft. The piston then starts traveling towards the crankshaft drawing the air-fuel mixture into the combustion chamber. When the piston reaches bottom dead center (BDC), meaning that the piston is at its closest position to the crankshaft, the intake valve closes. This is then the beginning of the compression stroke, during which the piston returns to TDC. The fuel-air mixture is compressed during this stroke to raise its temperature closer to its ignition point. When the piston reaches TDC for the second time, the power stroke is initiated. The piston then begins its return to BDC, when just passed TDC, a spark is generated from the spark plug. Spark is generated by a permanent magnet on the flywheel that rotates past a pickup coil. The spark then causes the mixture to combust, causing it to vaporize. The burning of the gas results in an increase of temperature, which causes the gas to expand. The expansion increases the pressure in the combustion chamber, which forces the piston back toward the crankshaft. When the piston reaches BDC for the second time it begins the exhaust stroke. The piston is then driven back towards TDC due to the rotational momentum of the crankshaft. As the piston returns to TDC the exhaust valve opens allowing the remaining gases to be forced out of the chamber. As the piston reaches TDC, the exhaust valve closes and the cycle repeats itself.
Product Testing and Analysis
Process Comparison
The assembly of this engine was nearly the reverse of the disassembly and went much more smoothly.Using our disassembly directions it was much easier to find the proper socket sizes to apply to each fastener. The only notable difference was during the assembly of the valve springs. While removing the valve clips was very simple inserting them was much more difficult. The valve clips attach the valve springs to the valves. Reinserting them requires either a valve spring compressor tool or two sets of hands.
Besides the difficulty with the valve springs the assembly was much easier than the reassembly. At times the disassembly required the use of brute force and in some situations multiple hammers to remove components that had become firmly attached over the last 2 - 3 decades. Since these natural adhesives had been overcome and cleaned away the assembly went smoothly and was completed in 2.5 hours.
