Professional Shop Manual RT 75 Rear Tine Tiller 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 About the text format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Fasteners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Assembly instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Understanding model and serial numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 The RT 75 Series Tiller . .
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Introduction CHAPTER 1: INTRODUCTION Professional Service Manual Intent: This manual is intended to provide service dealers with repair and overhaul procedures for the RT&% series tiller. 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.
RT 75 • Be prepared in case of emergency: ! CAUTION Keep a fire extinguisher nearby Keep a first aid kit nearby Keep emergency contact numbers handy • Replace any missing or damaged safety labels on shop equipment. • Replace any missing or damaged safety labels on equipment being serviced. • Remember that some hazards have a cumulative effect. A single exposure may cause little or no harm, but continual or repeated exposure may cause very serious harm.
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).
RT 75 The RT 75 series tiller The RT 75 tiller is a new tiller line that was introduced for the 2014 model year. This is a rear tine, counter rotating tiller that features: • Ball bearings on the wheel and tine shafts • Bronze worm gears. • A neutral lever to disengage the transmission. Figure 1.1 Understanding model and serial numbers The model number of the RT 75 tiller described in this manual is 21AC482R710. The break down of what the model number means is as follows: • 21 . . . . . . . . . . . .
Introduction Maintenance chart Maintenance item Each use Check engine oil * Check air filter * Check transmission oil * Check for loose/broke tines * Check & gap spark plug Check cooling fins Each 25 hrs. use Each 50 hrs.
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Belts CHAPTER 2: BELTS The RT 75 tiller has two belts; a forward drive belt and a reverse belt. Both belts have to come off together. MTD recommends replacing both belts at the same time. To remove/replace the belts: screws 1. Disconnect and ground the spark plug wire. 2. Remove the two screws that secure the belt cover. See Figure 2.1. 3. Swing the belt cover up and off of the tiller. 4. Slide the forward drive belt off of the engine pulley. 5.
RT 75 7. Remove the four screws that secure the transmission pulley shield using a 3/8” wrench. See Figure 2.3. NOTE: The tire was removed for this picture. It is not required to remove the tire to remove the belts. screws Figure 2.3 8. Push both belts down onto the transmission pulley. See Figure 2.4. 9. Unhook the reverse idler spring. See Figure 2.4. reverse idler spring belts pushed down Figure 2.4 lock washer 10. Unhook the reverse cable Z-fitting from the reverse idler bracket. 11.
Belts 12. Remove the nut that secures the transmission pulley using a 7/8” socket and an impact wrench. See Figure 2.6. 7/8” nut 13. Slide the transmission pulley and both belts off together. Figure 2.6 forward drive belt reverse belt hub 14. Position the new belts on the transmission pulley. See Figure 2.7. 15. Install the belts by following steps 1 through 13 in reverse order. NOTE: The transmission pulley has a star shaped center hole.
RT 75 Reverse drive belt Forward drive belt Engine Pulley Transmission pulley Belt Routing 10
Cables CHAPTER 3: CABLES The RT 75 tiller has a forward drive cable and a reverse drive cable. The forward drive cable is actuated by a bail that the operator squeezes. The reverse drive cable is actuated by a lever. See Figure 3.1. reverse lever forward drive bail Figure 3.1 The shape of the drive bail and reverse lever will help prevent the operator from engaging the reverse lever while in the forward mode.
RT 75 Forward drive cable To remove/replace the forward drive cable: 1. Disconnect and ground the spark plug wire. 2. Disconnect the black cable fitting from the handle bar bracket. See Figure 3.3. NOTE: A ford fuel line tool is useful to compress the ears on the cable fitting while removing it. See Figure 3.4. Disconnect the cable fitting Figure 3.3 Ford fuel line tool Figure 3.4 3. Unhook the Z-fitting from the forward drive bail. 4. Remove the two screws that secure the belt cover.
Cables Disconnect this cable 6. Loosen, but do not remove, the screw securing the cable pulley. See Figure 3.6. 7. Slip the cable off of the pulley. 8. Disconnect the black cable fitting from the cable bracket. See Figure 3.6. 9. Unhook the spring end of the cable from the forward idler bracket. See Figure 3.7. Loosen this screw Figure 3.6 NOTE: The spring end of the cable is to help prevent over tensioning of the drive belt. 10.
RT 75 Reverse drive cable To remove the reverse drive cable: 1. Disconnect and ground the spark plug wire. 2. Disconnect the red cable fitting from the handle bar bracket. See Figure 3.8. 3. Unhook the Z-fitting from the reverse drive lever. Disconnect the cable fitting Figure 3.8 4. Remove the two screws that secure the belt cover. See Figure 3.9. Remove these screws NOTE: The left screw has a washer to prevent the slot in the cover from opening up as the screw is tightened. 5.
Cables Disconnect this cable 9. Disconnect the red cable fitting from the cable bracket. See Figure 3.11. 10. Disconnect the cable Z-fitting. 11. Install the reverse cable by following the previous steps in reverse order. 12. Test run the tiller in a safe area before returning it to service. Figure 3.
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Engine CHAPTER 4: ENGINE At the time this manual was written, a Briggs and Stratton engine was the only engine option for the RT 75 tiller. If a different brand of engine is used, the removal/replacement procedures will be essentially the same. Engine removal To remove/replace the engine: Remove these screws 1. Disconnect and ground the spark plug wire. 2. Remove the two screws that secure the belt cover. See Figure 4.1. 3. Swing the belt cover up and off of the tiller. 4.
RT 75 7. Slide the forward drive belt off of the engine pulley. 8. Loosen the nut and bolt that secures the reverse idler pulley to the idler bracket, using a pair of 7/16” wrenches. See Figure 4.3. 9. reverse idler pulley Slide the reverse belt past the belt guards and off of the idler pulley. Figure 4.3 Unhook spring 10. Unhook the reverse idler spring. See Figure 4.4. 11. Unhook the reverse cable Z-fitting from the reverse idler bracket. Belts pushed down Figure 4.4 12.
Engine motor cover plate 15. Transfer the engine pulley, reverse idler bracket and the motor cover plate to the new engine. See Figure 4.6. engine pulley reverse idler bracket Figure 4.6 NOTE: If the idler pulley was removed from the idler bracket, it must be reassembled so that the spot welds face away from the idler bracket to ensure proper belt alignment. See Figure 4.7. Spot welds must face away from the idler bracket Figure 4.7 Engine Installation 16.
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Transmission Removal CHAPTER 5: TRANSMISSION REMOVAL Transmission removal Loosen screw and slide cable off of the pulley 1. Remove the belts by following the procedures described in Chapter 2: Belts. 2. Remove the engine by following the steps described in Chapter 4: Engine Removal. 3. Loosen the forward drive cable pulley, using a 3/8” wrench, and slide the cable off of the pulley. See Figure 5.1. 4. Unhook the cable. See Figure 5.2. Figure 5.1 Unhook the cable Figure 5.
RT 75 5. Unhook the idler bracket spring. See Figure 5.3. idler bracket spring Figure 5.3 6. Remove the wheels. 7. Support the wheel shafts with wood blocks. See Figure 5.4. NOTE: Any time the wheels are removed, or once a year, the wheel shafts should be coated with antiseize or grease. Support the wheel shafts with wood blocks Figure 5.4 8. Remove and discard the cotter pin that holds the neutral lever to the transmission shifter fork. See Figure 5.5. Neutral lever cotter pin Figure 5.
Transmission Removal 9. Disconnect the front of the drag bar, using a 5/8” wrench and a 1/2” wrench. See Figure 5.6. Remove nut and bolt Drag bar Figure 5.6 handle mount nuts and bolts 10. Remove the four screws that hold the frame rails to the transmission, using a 1/2” wrench. See Figure 5.7. 11. Loosen, but dot remove, the handle mount nuts and bolts. screws Figure 5.7 Remove these screws 12.
RT 75 13. Lift the frame, handle bar and tine shield off as one unit. See Figure 5.9. Figure 5.9 14. Remove the tines: 14a. Remove the bow tie clip and clevis pin. See Figure 5.10. 14b. Slide the tines off of the shaft. NOTE: Any time the tines are removed, or once a year, the tine shafts should be coated with anti-seize or grease. Bow tie clip Figure 5.10 Direction of rotation NOTE: When installing the tines, make sure the curve of the tine is facing the direction of rotation. See Figure 5.11.
Transmission Removal 15. Remove the idler bracket, using a 1/2” wrench. See Figure 5.12. 16. Install the transmission by following the previous steps in reverse order. 17. Test run the tiller in a safe area before returning it to service. idler bracket Figure 5.
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Transmission Overhaul CHAPTER 6: TRANSMISSION OVERHAUL The 460 series transmission is equipped with a neutral feature that will disengage the wheel shaft from the transmission. This allows the tiller to be pushed without the engine driving it. The neutral mechanism is a dog clutch that is splined to the wheel shaft. When the neutral lever is moved to the engaged position, the dog clutch slides into the worm gear, allowing the transmission to drive the wheel shaft.
RT 75 7. Remove the retaining ring that secures the right wheel shaft bearing, using a pair of snap ring pliers. 8. Remove the eight screws that secure the side cover to the transmission housing, using a 3/8” wrench. See Figure 6.3. NOTE: It is not necessary to remove the snap ring and the left wheel shaft bearing. They will come off with the side cover. Alignment pins Side cover Figure 6.3 9. Gently pry the side cover off of the transmission. See Figure 6.4.
Transmission Overhaul 15. Remove the four hex flange screws holding the rear transmission cover to the transmission housing, using a 1/2” wrench. See Figure 6.6. 16. Wedge a sharp 5-in-1 painters tool or putty knife in between the cover and the transmission housing. 17. Pry the cover off. 18. Clean the gasket from the rear transmission housing and cover. NOTE: The rear cover does not have a fill plug. Rear transmission cover Figure 6.6 19. Remove the tine shaft oil seals from the transmission housing .
RT 75 25. Drive the tine shaft to the left, forcing the left tine shaft bearing out of the transmission housing. 26. If the bearing is stuck, use a block of wood and a large hammer. NOTE: The washer will be damaged by the Hi-Pro key. 27. Remove the tine shaft. 28. Remove the remaining lower hex flange screw securing the rear bearing cap, using a 1/2” wrench. See Figure 6.9. Place punch here NOTE: The top two screws were removed with the depth bar bracket. 29.
Transmission Overhaul 33. Measure the overall thickness of the rear bearing shims using a dial caliper. See Figure 6.11. 34. Record the measurement for future reference. Figure 6.11 Front bearing 35. Inspect the rear tapered roller bearing assembly for damage or wear. 36. Thoroughly clean the exposed portion (front) of the drive shaft. 37. Slowly push the drive shaft assembly rearward and out of the transmission assembly.
RT 75 40. Slide the shifter fork out of the dog clutch collar. 41. Remove the snap ring that retains the spring and washer, using a pair of snap ring pliers. 42. Slide the washer, spring, and the dog clutch collar off of the wheel shaft. 43. Remove the two snap rings that secure the worm gear to the wheel shaft. Worm gear Snap ring Snap ring Snap ring Shifter fork Clutch collar Spring Washer Figure 6.14 44. Remove the front drive shaft oil seal, using a flat blade screwdriver. 45.
Transmission Overhaul Transmission assembly Dial Caliper Washers 1. Thoroughly clean the entire transmission housing. 2. Clamp the transmission housing in a soft jawed vice. 3. Make certain all the drive shaft components are accounted for. 4. Locate both hex flange screws that were securing the hood bracket to the transmission assembly. 5. Locate two sets of flat washers that would equal approximately 0.120” in thickness (the thickness of the hood bracket).
RT 75 Snap ring grooves 10. Assemble the wheel shaft and the neutral assembly. 10a. In the middle of the wheel shaft there is a section that is splined. On one side of the splines there are two snap ring grooves. On that side, install a snap ring in the grove closest to the splines. See Figure 6.19. Dog clutch side Worm gear bearing surface Figure 6.19 10b. Slide the worm gear onto the wheel shaft so that it rests against the snap ring, on the side opposite of the splines.
Transmission Overhaul Spring 10e. Slide the spring onto the wheel shaft so that it is next to the clutch collar. Washer 10f. Slide the washer onto the wheel shaft so that it is against the spring. 10g. Install the third snap ring while compressing the spring and washer. See Figure 6.22. Snap ring Clutch collar Figure 6.22 11. Slide the shift fork into the groove in the clutch collar. See Figure 6.23. 12. Slide the wheel shaft assembly into the transmission housing.
RT 75 22. Install the tine shaft. It will pass through the bearing bore, through the tine shaft worm gear and out the other side of the transmission. 23. Slide the Hi-Pro key into the tine shaft worm gear. 24. On each side, slide the washer over the tine shaft. 25. Insert the tine shaft bearings over the tine shaft until they pass the snap ring grooves in the transmission housing. Snap ring NOTE: A bearing installation tool can be made using a 1” I.D. PVC pipe by 7” long. 26.
Transmission Overhaul Magnetic Base 32. Shim the rear drive shaft bearing to set the drive shaft end play to 0.005” - 0.015” (0.13 -. 038 mm). Drive Shaft 32a. Set up a dial indicator at the front of the drive shaft. See Figure 6.27. Dial Indicator Figure 6.27 32b. Rotate the tine shaft towards the rear of the transmission to seat the drive shaft into the rear bearing cap. See Figure 6.28. NOTE: A screwdrivers or punch can be inserted into the shaft for leverage to rotate it. 32c.
RT 75 34. Secure the rear bearing cap to the transmission assembly with the hex flange screws with the washers used earlier, using a 1/2” wrench. NOTE: Tighten the hex screws to a torque of 100 in lbs (11 Nm). NOTE: Leave the two top screws in place until the sealant has cured. Then they should be removed. 35. Verify the end play is between 0.005” - 0.015” by repeating step 32a. through step 32e. 36. Install both of the wheel shaft seals. 37. Install both of the tine shaft seals. 38.
Tines CHAPTER 7: TINES Tines Euro tines The RT 75 tiller is a counter rotating tiller equipped with Euro tines. If the tines are properly installed, the tines will cut into the ground and break up the soil. If the tines are installed backwards, the tines will “hammer” the ground, making the machine hard to control and will not till the soil. See Figure 7.1. Figure 7.1 Sharp point As the tines dig through the ground, the grinding action of the soil will put a sharp edge on the tines.
RT 75 1. Remove the tine hood end cover and the side shield. See Figure 7.3. Figure 7.3 2. 3. Remove the tine assemblies by removing the clevis pin and bow tie clip that secures the tine assemblies to the tine shaft on the transmission. See Figure 7.4. NOTE: Replace the nut and bolt if they show signs of wear or damage. bow tie clip Slide the assemblies off of the tine shaft. Clevis pin NOTE: If the hub assemblies are frozen to the tine shaft, a hub puller can be used to remove them. Figure 7.
Tines Right Right Hand Tine RightHand HandTine Tine Left Left Hand Tine LeftHand HandTine Tine NOTE: When installing the tines, it is important that the correct tines are used and they are installed in the proper orientation. 5. Hold Hold with the sharp edge facing you Holdwith withthe thesharp sharpedge edgefacing facingyou you To determine which tine is right or left: 5a. Hold the tines with the cutting edge towards you. See Figure 7.6. 5b. If the tine curves to the left, it is a left handed tine.
RT 75 9. Apply anti-seize to the tine shaft. 10. Installing the assembly. 11. When correctly installed: • The end of the tine holder with the clevis pin hole should face towards the transmission. • The outside tines should curve inward • The tines should be bolted to the outboard side of the plate on the tine holder. See Figure 7.9. clevis pin Figure 7.9 12. Insert the tine hood end panel. Secure it with the center wing nut. 13. Install the side shield.
Swivel Handle CHAPTER 8: SWIVEL HANDLE Handle bar To remove/replace the handle bar: 1. Disconnect the forward and reverse cables from the handle bar, by following the procedures described in Chapter 3: Cables. 2. Remove the nut and bolt that secures the throttle lever to the handle bar, using a pair of 7/16” wrenches. See Figure 8.1. 3. Unthread the swivel rod knob. See Figure 8.2. throttle lever Figure 8.1 swivel rod knob Figure 8.
RT 75 4. Remove and discard both of the cable ties from the handle bar. See Figure 8.3. cable ties Figure 8.3 5. Remove and discard the outer cotter pin that secures the swivel rod to the swivel latch. See Figure 8.4. NOTE: Do not remove the inner cotter pin. 6. inner cotter pin outer cotter pin washer Remove the swivel rod and washer. Figure 8.4 7. Remove the handle adjustment crank. See Figure 8.5. handle adjustment crank handle mounting bolt Figure 8.
Swivel Handle nut retension bracket NOTE: There is a nut retension bracket on the left side of the handle bar swivel mount. When the handle mounting nut and bolt is removed, the bracket and the upper nut will fall off. See Figure 8.6. 8. Remove the handle mounting nut and bolt. 9. Remove the handle bar from the machine. 10. If replacing the handle bar: 10a. Remove the forward drive bail. 10b. Remove the reverse lever. 10c. Remove the front cover and swivel rod bracket. 11. Figure 8.
RT 75 Swivel Bracket To rebuild the swivel assembly: 1. Remove the handle bar assembly, by following the procedures described in the previous section of this chapter. upper jam lock nut NOTE: It is advisable to rebuild the swivel assembly on the machine. Having the lower bracket mounted to the frame provides stability while torquing the lower nut. 2. Remove the upper jam lock nut from the swivel assembly, using a 15/16” wrench. See Figure 8.7. Figure 8.7 3. Remove the flat washer. See Figure 8.8.
Swivel Handle 5. Remove the Belleville washer. See Figure 8.10. 6. Remove the nut and bolt that the swivel latch and spring pivot on, using a pair of 9/16” wrenches. See Figure 8.11. 7. Remove the swivel latch and spring. 8. Lift the upper swivel latch bracket off of the machine. 9. If the lower bracket is damaged or worn, remove and replace it by removing the four nuts and bolts that hold it down, using a pair of 1/2” wrenches. See Figure 8.12. Belleville washer Figure 8.
RT 75 12. Install the upper swivel bracket. 13. Install the swivel latch and spring. 14. Install the Belleville washer. 15. Install the lower nut and tighten it to a torque of 240 - 270 in lbs (27 - 31 Nm). See Figure 8.13. 16. Install the flat washer. 17. Install the upper locking jam nut. 18. Install the handle bar by following the procedures described in the previous section of this chapter. 19. Test run the unit in a safe area before returning it to service.
MTD Products Inc - Product Training and Education Department FORM NUMBER - 769-09590-00 12/2013
