Professional Shop Manual 300 Series Snow Thrower NOTE: These materials are for use by trained technicians who are experienced in the service and repair of outdoor power equipment of the kind described in this publication, and are not intended for use by untrained or inexperienced individuals. These materials are intended to provide supplemental information to assist the trained technician. Untrained or inexperienced individuals should seek the assistance of an experienced and trained professional.
Table of Contents Chapter 1: Introduction .........................................................................................1 About the text format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Fasteners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Assembly instructions .
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INTRODUCTION CHAPTER 1: INTRODUCTION Professional Service Manual Intent: This manual is intended to provide service dealers with information that will help them maintain and repair the MTD 2-Stage snow thrower. Disclaimer: The information contained in this manual is correct at the time of writing. Both the product and the information about the product are subject to change without notice. About the text format Certain flags and key words are used to indicate the nature of the text that accompanies them.
INTRODUCTION Safety This Service Manual is meant to be used along with the Operator’s Manual. Read the Operator’s Manual and familiarize yourself with the safety and operational instructions for the equipment being worked on. Keep a copy of the Operator’s Manual for quick reference. Operator’s manuals may be viewed for free at the brand support website. It will be necessary to have the complete model and serial number for the equipment.
INTRODUCTION Fasteners • The fasteners used on the equipment described in this manual, and the engine that powers it are a combination of metric and fractional inch. For this reason, wrench sizes are frequently identified in the text, and measurements are given in U.S. and metric scales. • If a fastener has a locking feature that has worn, replace the fastener or apply a small amount of releasable thread locking compound such as Loctite® 242 (blue).
INTRODUCTION The 300 series snow thrower The 300 series snow thrower is designed for the residential user with moderate snow removal requirements See Figure 1.0. Features: • 2-stage design • Light-weight: 120 lbs. (54 kg.) typical • 22” clearing swath • Self-propelled, with internal clutch transmission • Some versions are single-speed • Some versions have 3 ground speeds Figure 1.
Maintenance CHAPTER 2: MAINTENANCE Proper maintenance and storage key factors in keeping outdoor power equipment dependable. Encourage your customers to bring snow equipment in for service and storage preparation at the end of each winter. Attending to their snow throwers maintenance in the early spring will bring-in some pre-season work and prevent the barrage of anxious phone calls when there is 8” of snow in their driveway.
MAINTENANCE 6. Spray penetrating oil on the joints between; • The auger shaft and the bearings in the auger housing that support it • the augers and the auger shaft • the augers and the shear pins • the impeller shaft and the impeller 7. Check and adjust the shave plate and the skid shoes; 7a. Replace the shave plate if it is worn. It is generally best to install the new shave plate with new carriage bolts and locking nuts. Skid shoe Mounting bolts 7b. Replace the skid shoes if they are worn.
Maintenance Traction drive system maintenance NOTE: Be careful to keep oil and grease away from the belts and pulleys. NOTE: Replace any worn or damaged parts discovered during inspection. NOTE: If a part has failed prematurely, identify and correct the cause of the failure. 1. Loosen the wheel bolts using a 1/2” wrench. 2. If not previously removed, take the belt cover off; 2a. Remove the screw on the right side of the of the belt cover using a 3/8” wrench. 70T Bull gear 2b.
MAINTENANCE FINAL 1. Reinstall the belt cover. 2. Spray some penetrating oil into the points of the control cables where the cable core enters the cable housing. 3. Re-fill the crankcase with fresh 5W-30 engine oil, and add a small amount of fresh gasoline to the fuel tank. 4. Test-run the snow thrower, testing all operation and safety features. 5. Prepare the engine for storage; • Drain or run all of the fuel out of the engine.
TRACTION DRIVE SYSTEM CHAPTER 3: TRACTION DRIVE SYSTEM Description of the traction drive system • A belt transfers power from the engine crankshaft to the input pulley of the transmission. • A spring-loaded idler pulley keeps the belt under constant tension. • On the three-speed version, a cable operated variable speed pulley changes the drive ratio to the transmission: the sheaves of the pulley close or spread to change its effective circumference.
TRACTION DRIVE SYSTEM DRIVE BELT REPLACEMENT: SINGLE-SPEED SYSTEM 1. Remove the belt cover: 1a. Remove the screw on the right side of the belt cover with a 5/16” wrench or screwdriver. See Figure 3.3. 1b. Squeeze the locking tabs on the belt cover inward while lifting. 1c. Work the cover from between the engine and discharge chute Screw ! CAUTION Allow the engine to cool, then drain the fuel and oil from the engine before starting any service procedure. Lock tab Figure 3.3 2.
TRACTION DRIVE SYSTEM 5. Rock the transmission forward to provide the slack needed to removed the drive belt from the transmission pulley. NOTE: The auger drive belt must be removed to remove or install the self-propel drive belt. See Figure 3.6. 6. Slip the auger belt off of the front engine pulley sheave 7. Route the drive belt between the upper and lower pulleys. 8. Replace the drive belt with a new one. Use only the correct OEM part number belt. 9.
TRACTION DRIVE SYSTEM 4. Remove the spark plug and insert a 20” piece of starter rope to act as a piston stop and prevent the engine from turning. 5. Remove the bolt that holds the auger drive pulley to the engine crankshaft with a 9/16” wrench. See Figure 3.10. Auger drive pulley Figure 3.10 NOTE: The auger belt drive pulley is a split-sheave design. 6. Slide the outer auger pulley sheave off of the crank shaft and remove the auger belt. See Figure 3.11. Inner sheave Outer sheave Figure 3.11 7.
TRACTION DRIVE SYSTEM NOTE: .To replace the drive belt on a three speed drive system, the speed actuator arm needs to be removed. 8. Loosen the jam nuts that hold the speed control cable to the bracket on the engine. 9. Adjust the nuts to provide slack in the cable. 10. Disconnect the speed control cable from the actuator arm. See Figure 3.13. Actuator arm Speed control cable Figure 3.13 11. Remove the bow tie clip from the pivot rod. See Figure 3.14. 12.
TRACTION DRIVE SYSTEM NOTE: A sealed ball bearing and the outer half of the variable speed pulley will come-off with it. 15. Slip the belt off of the crankshaft. See Figure 3.16. 16. Reach from under the snow thrower and pull the belt off of the transmission pulley. Figure 3.16 17. Lift the belt out of the snow thrower. See Figure 3.17. Belt Inner sheave Figure 3.17 18. Check the operation of the belt tensioner and variable speed mechanism while the belt is out of the snow thrower; See Figure 3.
TRACTION DRIVE SYSTEM DRIVE ENGAGEMENT CABLE REPLACEMENT 1. Unhook the z-fitting from the drive engagement control bail: Right side: goes straight in 1a. Squeeze the bail to release the right side of the bail from the handlebar. 1b. Once the right side is released, pivot the bail to unhook the left side of it from the left handlebar. 1c. With the control bail released from the handlebar, it can be rotated to release the Z-fitting. See Figure 3.19. Left side: extra hook in the end of the bail Figure 3.
TRACTION DRIVE SYSTEM 6. Release the cable from the transmission housing by squeezing the barbs that lock the cable housing into the bracket on the transmission. See Figure 3.22. 7. Route the cable out of the frame. 8. If the snow thrower has the three speed drive system; Cable bracket • The ground speed is controlled by the speed selector lever located on the left side on the upper handle bars.
TRACTION DRIVE SYSTEM SPEED CONTROL CABLE REPLACEMENT 1. Remove the belt cover: 1a. Remove the screw on the right side of the belt cover with a 5/16” wrench or screwdriver. See Figure 3.23. 1b. Squeeze the locking tabs on the belt cover inward while lifting the cover. 1c. Work the cover from between the engine and discharge chute Screw Lock tab Figure 3.23 2. Remove the jam nut that holds the speed control cable housing to the cable bracket on the engine. Use a pair of 1/ 2” wrenches. See Figure 3.24.
TRACTION DRIVE SYSTEM 5. Remove the three phillips head screws that hold the cover on the speed control housing. See Figure 3.26. Speed control housing Figure 3.26 6. Carefully remove the speed control cable from the speed control housing. See Figure 3.27. Speed control cable • Lift the top of the cable out of the recess in the speed control housing. • Release the barrel from the keyhole slot in the speed control lever. 7.
TRACTION DRIVE SYSTEM TRANSMISSION REMOVAL 1. Disconnect the z-fitting from the drive control on the handle bar. 2. Detach the cable mounting block from the left side of the handle bars. 3. Cut the cable retaining straps that secure the cable to the handle bars. 4. Tip the snow thrower forward onto it auger housing. 5. Remove the nut on the spring anchor bolt. 6. Release the cable from the transmission housing with needle nose pliers 7.
TRACTION DRIVE SYSTEM 12. 13. Slide the bearing and shim out from each side of the frame. See Figure 3.32. Washer Inspect the bearings for wear or damage. NOTE: Apply a coating of grease to the shaft and bearing before reassembling. 14. Move the transmission to the left and pivot it forward to remove it from the frame. 15. Reverse the removal process to install a new transmission. Bearing Out-put shaft • Lubricate the contact points where the transmission out put shaft ride on a bushing.
TRACTION DRIVE SYSTEM TRANSMISSION INTERNALS NOTE: the transmission has been broken down to satisfy professional curiosity, this information is not intended to suggest that the transmission is to be serviced. If you see any of these parts in the course of working on a 300-series snow thrower, you have done something wrong. Cone hub clutch • The Cone hub clutch plates are tapered to fit into the tapper on the helical gear.
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AUGER SYSTEM CHAPTER 4: AUGER SYSTEM System Description • The auger and impeller are driven by a belt from the engine crankshaft. • An idler pulley is drawn against the belt when the control bale is engaged. • The belt then drives a large pulley on the back of the impeller shaft. • The impeller shaft enters the rear of the auger housing, driving the impeller through a roll pin. • The impeller shaft continues forward to a “T” shaped worm-gear transmission. The transmission drives the auger shaft.
AUGER SYSTEM 4. Disconnect the auger control cable from the control bail. This will allow enough slack in the auger control cable to free the auger belt from the engine pulley. See Figure 4.3. Bail Cable Figure 4.3 5. Use your thumb to pull the auger brake far enough away from the auger pulley to slip the belt off of the pulley. See Figure 4.4. Auger pulley Brake Figure 4.4 6. Remove the belt from the engine pulley and idler pulley. See Figure 4.5. 7. Slip the belt out of the snow thrower.
AUGER SYSTEM Auger control cable replacement 1. Remove the belt cover as described in the “BELT REMOVAL” section of this chapter. 2. Slip the cable off of the cable guide pulley located on the left side of the frame. See Figure 4.6. Cable Cable guide NOTE: It may be necessary to loosen the screw that holds the cable guide pulley using a 3/8” wrench. Figure 4.6 3. 4. Use the slack created by the previous step to unhook the Zfitting at the top end of the cable from the auger control bail.
AUGER SYSTEM 6. Carefully slip the auger control cable out of the speed control housing. See Figure 4.9. Auger control cable Figure 4.9 7. On single-speed models, remove the nut and bolt that hold the cable bracket to the handlebar. See Figure 4.10. 8. Slip the auger control cable out of the bracket. Inset: cable bracket Auger control cable Figure 4.10 9. 10. Pull the cable upward from the opening created by removing the belt cover.
AUGER SYSTEM 11. Unbolt the auger cable control bracket from the right side of the frame using a 3/8” wrench. 12. Release the auger control cable from the bracket on the right side of the frame. See Figure 4.12. 13. Install the replacement cable by reversing the removal process. 14. Check and adjust the cable bracket any time the auger belt or auger cable have been replaced; Cable bracket Disconnecting the cable 14a.
AUGER SYSTEM Auger housing Removal NOTE: Auger housing removal is necessary for any repairs to the auger, impeller, or auger transmission. 1. Remove the auger belt following the instructions in the AUGER BELT REMOVAL section 2. Loosen (do not remove) the bolt that holds the cable guide pulley to the frame. 3. Disconnect the auger control cable from the control bail on the handlebar. 4. Disconnect the spring end of the auger control cable from the auger pulley brake arm. See Figure 4.13.
AUGER SYSTEM Auger Housing disassembly: Pulley removal 1. Remove the bolt that holds the auger pulley to the impeller shaft using a 1/2” wrench. See Figure 4.15. Auger pulley NOTE: The auger brake may need to be moved over briefly to clear the pulley. 2. Pull the auger brake clear of the pulley. Figure 4.15 3. Inspect the brake spring idler bracket and idler pulley for wear or damage. See Figure 4.16. Figure 4.
AUGER SYSTEM Auger housing disassembly: Impeller shaft bearing replacement 1. Separate the auger housing from the engine drive unit and remove the pulley. 2. Remove the two nuts that secure the bearing housing, using a 1/2” wrench. See Figure 4.17. Bearing housing Nuts Figure 4.17 3. Slide the bearing and spacer off of the impeller shaft to inspect for wear. See Figure 4.18. Spacer Bearing Figure 4.18 4. The auger shaft is supported by bearings at each end. The bearings are fixed in housings.
AUGER SYSTEM 5. Slide the auger and impeller assembly from the auger housing as one assembly See Figure 4.20. 6. Slide the bushing housings and bearings off of the auger shafts. NOTE: Before re-installing, apply grease to the bushings and impeller shaft. NOTE: Inspect the auger shaft and bushings for wear. Figure 4.
AUGER SYSTEM Auger housing disassembly: flight removal There are four individual auger flies. The flies draw snow inward to the impeller. If any one flight is damaged, it can be replaced individually. 1. Remove the auger shaft assembly, complete with the auger transmission, impeller shaft, and impeller. See Figure 4.21. Flights Figure 4.21 2. Remove the auger shaft bearings and washers. See Figure 4.22. 3. Remove the bow tie clips and shear pins that transfer power to the flights from the auger shaft.
AUGER SYSTEM NOTE: There are right hand left hand flights. See Figure 4.23. • The flights are stamped “L” and “R” to indicate their position as seen from the point of view of the person operating the snow thrower. • The identifying “L” and “R” have been highlighted for clarity in this illustration. • There are 2 L-flights and 2 R-flights on each machine. Figure 4.23 5. When correctly installed on the auger shaft, the front inside edge of the flights will form a letter “A”.
AUGER SYSTEM Auger Housing disassembly: impeller brake replacement 1. The idler pulley that applies tension to the auger belt can be reached for removal by simply taking-off the belt cover. • An idler pulley is mounted to an arm that is pulled by the auger control clutch cable. • The other end of the arm works as a brake, against the pulley that turns the impeller shaft. • When that cable is pulled, the idler pulley tightens the belt, engaging the impeller and auger.
AUGER SYSTEM 6. Remove the brake arm; use a 15/16” wrench on the head of the brake arm pivot bolt, and a 9/16” socket to reach through the hole in the impeller. See Figure 4.28. 7. As the brake arm comes free of the auger housing, there will be slack in the brake spring. 8. Unhook the brake spring from the brake arm. 9. Instal the brake arm by reversing the removal process.
AUGER SYSTEM Auger housing disassembly: Impeller removal 1. Remove the auger shaft assembly, complete with the auger transmission, impeller shaft, and impeller. See Figure 4.29. Description: • The impeller is fastened to the impeller shaft by two roll pins: one in front of the impeller, and one behind it. • The front roll pin can be reached easily once the impeller shaft is out of the snow thrower. • The rear roll pin is recessed into the back of the impeller. ! CAUTION 2.
AUGER SYSTEM Auger Transmission NOTE: NOTE: The auger transmission on this model is generally replaced as a complete unit. See Figure 4.32. • The complete transmission assembly is relatively inexpensive. • All parts are available, but they are not described in the Illustrated Parts List. • Circumstances that may merit rebuilding an auger transmission: -The damage may be minimal Figure 4.
AUGER SYSTEM NOTE: There is a lube port on the top of the transmission. See Figure 4.33. • The transmission contains Alvania EP grease (part number 737-0168A, 8 oz. tube), though it should not need to be refilled in normal operation. NOTE: The components of the gear box are: • The impeller shaft with a worm gear. • 20T helical gear • A flange bearing and thrust bearing positioned behind the worm gear • .25” OD x 1.25” LG dowel pin • Oil seal towards the rear of the gear box Figure 4.
AUGER SYSTEM Chute 1. The chute assembly is easily removed from the auger housing using a 7/16” wrench. It may be necessary to reach into the auger housing to hold the carriage bolts in place during removal and installation of the chute. See Figure 4.35. Figure 4.35 Upper chute 2. The upper chute may also be separated from the chute base by releasing the collar. See Figure 4.36. Collar Chute base Figure 4.36 Detent spring • The collar fits in a specific orientation with the upper chute.
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