TUFF-TORQ K61A TRANSAXLE SERVICE MANUAL Table of Contents – Page 1 of 2 SAFETY INFORMATION SPECIFICATIONS REMOVING THE TRANSAXLE FROM THE TRACTOR TRANSAXLE DISASSEMBLY AND INSPECTION PINION DIFFERENTIAL GEAR CENTER CASE MOTOR SHAFT PUMP SHAFT TRANSAXLE ASSEMBLY AND ADJUSTMENT BYPASS RETURN BRAKE INTERLOCK NEUTRAL ADJUST ECCENTRIC PUMP SHAFT SWASH PLATE PUMP CYLINDER BLOCK MOTOR SHAFT CENTER CASE MOTOR SHAFT AND CENTER CASE INSTALLATION DIFFERENTIAL GEAR AXLE SHAFTS AND DIFFERENTIAL INSTALLATION PINION TRANS
TUFF-TORQ K61A TRANSAXLE SERVICE MANUAL Table of Contents – Page 2 of 2 BELTS AND LINKAGE -Continued HYDROSTATIC CONTROL LINKAGE DESCRIPTION AND OPERATION LUBRICATION PEDAL ADJUSTMENT CRUISE CONTROL DESCRIPTION AND OPERATION COMPONENTS PLATE-HYDROSTATIC CONTROL ARM AND HOUSING BRACKET MAGNET MAGNET BRAKE SWITCH AND MOUNTING BRACKET RELAY TROUBLESHOOTING
R Tuff-Torq K61A Transaxle
About This Manual This manual was written expressly for servicing Tuff Torq K61A transaxles, as used in 1994--1999 260-Series Toro Wheel Horse tractors. The Toro Company has made every effort to make the information in this manual complete and correct. This manual was written for the service technician; basic mechanical/electrical skills are assumed. The Contents page lists the systems and the related topics covered in this manual.
Contents Safety Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Removing the Transaxle from the Tractor . . . . . . . . Transaxle Disassembly and Inspection . . . . . . . . . . Pinion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Differential Gear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Center Case . . . . . . . . . . . . . . . . . . . . . . .
Safety Information This symbol means WARNING or PERSONAL SAFETY INSTRUCTION— read the instruction because it has to do with your safety. Failure to comply with the instruction may result in personal injury or even death. model K61A hydrostatic transaxle. The tractor and attachment operator’s manuals contain safety information and operating tips for safe operating practices.
Specifications Axle Torque Output Rated: . . . . . . . . . . . . . . . . . . . . . . . . 215 ft. lb. (290 NSm) Peak: . . . . . . . . . . . . . . . . . . . . . . . . . 654 ft. lb. (880 NSm) Maximum Input Speed . . . . . . . . . . . . . 3000 RPM Input Shaft Size . . . . . . . . . . . . . . . . . . . 0.58 in. (14.85mm) Reduction Ratio . . . . . . . . . . . . . . . . . . . 26.97:1 Axle Shaft Size . . . . . . . . . . . . . . . . . . . . 1.0 in. (25.4mm) Maximum Static Weight on Axle . . . . 584 lb.
Removing the Transaxle from the Tractor Disconnect the brake rod, control rod, tow valve rod, and reservoir hose from the top of the transaxle. Support the rear of the tractor with jack stands and remove the rear wheels. Remove the two bolts securing the transaxle support rods to the tractor frame. Working from the bottom of the tractor, remove the transaxle drive belt tension spring and drive belt from the transaxle pulley.
Transaxle Disassembly and Inspection Remove the shock absorber by detaching the E clip, washer, and cotter pin and its washer. Later models use a spring clip retainer to secure the shock absorber. Begin disassembly and inspection of the transaxle by thoroughly cleaning the outside surface of the transmission. IMPORTANT: Clean your work area thoroughly and cover the workbench with clean paper. This is extremely important as just one grain of sand can cause a hydrostatic transmission to fail.
Remove the differential gear assembly. Open the transaxle case by taking out the 13 perimeter 12mm bolts and the single center bolt. Pry the bottom half of the case free from the top half, using care not to damage the seating surface. Figure 11 Remove the left and right axle shaft and two bushings from the upper case. Figure 8 Lift the pinion shaft assembly from the upper case. There is a ball bearing on one end of the shaft and a bushing on the other end.
Measure the inside diameter of the bushings and the outside diameter of the left and right axle shaft. Disconnect the C arm from the push valve bypass shaft. Remove the two push pins, springs, and valves from the center case. Table 1 Measurement Should be: Bushings Inside Diameter 22.06-22.15mm (.868-.872″) Axle Shaft Outside Diameter 21.98-22mm (.865-.866″) Clearance 0.08-0.17mm (.003-.006″) Maximum Wear Limit 0.5mm (.
Carefully inspect the packings (o-rings) to ensure they are not deformed, cut, or scratched. Use new packings on reassembly. Remove the cylinder block from the pump shaft. IMPORTANT: Be sure the pistons do not fall out of the block during removal. IMPORTANT: When removing the sleeves, note that their valves are different, and therefore not interchangeable. The A1 valve, located farthest from the axle, has a small hole in it, in addition to the large hole in the center.
Measure the clearance between the swash plate and shift blocks. Inspect the swash plate, thrust bearing, thrust plates, and bushing for wear or damage. Replace with new parts if necessary. Replace both shift blocks and the swash plate with new parts if they are beyond the maximum wear limit. Table 3 Measurement Should be: Clearance 0.01-0.11mm (.0003-.004″) Maximum Wear Limit 0.15mm (.005″) Remove the spring and ring from the pump shaft.
Remove the shift blocks from the control shaft and inspect them for wear or damage. Replace if necessary. Remove the input shaft, seal, and bearing from the upper case. Remove oil seal and large snap ring from the upper case. Remove the input shaft and bearing from the case. Figure 28 Figure 30 Figure 29 Figure 31 Remove the two metal thrust pads from the upper case and inspect them for wear or damage. Replace both thrust pads with new parts if the maximum wear limit is exceeded.
Inspect the control shaft, fulcrum, and torsion spring for wear or damage and replace if necessary. Note: If servicing a transaxle with low to moderate use, it is not necessary to disassemble or remove any of the levers or linkages from the upper case, unless a part is damaged or there is an oil leak. If doing a complete rebuild, all shafts should be removed, inspected, and packings (o-rings) replaced.
Remove the brake rod and brake arm from the upper case. Drive the roll pin from the brake arm for the external band brake. Inspect the packing for cuts, scratches, or deformation. Figure 42 Figure 39 Remove the roll pin from the push valve bypass release arm. Remove the snap pin and washer from the brake rod. Disconnect the push valve bypass release arm from the bypass shaft. Figure 40 Figure 43 Remove the brake shaft from the upper case.
Pinion Differential Gear Remove the bearing, bushing, washer, and shaft gear from the pinion shaft. Remove the differential side gears, thrust washers, differential pinion gears, and differential pinion shaft from the final gear. Inspect all parts for wear or damage. Replace if necessary. Inspect all parts for wear or damage. Replace if necessary. Figure 45 Figure 46 Measure the inside diameter of the bushing and the outside diameter of the pinion shaft.
Center Case Motor Shaft Take out the two knock pins, plug, and packing (o-ring) (early models), if required. If the shaft bushings require replacement, remove them. Remove the cylinder block assembly from the motor shaft. Inspect the five cylinder bores for burrs or scoring. Figure 50 Figure 47 Inspect the five pistons and all parts of the cylinder block assembly for wear or damage. Inspect the center case by running your fingernail over its surface.
Pump Shaft Remove the snap rings, washer, bearing, and seal from the motor shaft (brake shaft). Remove the two snap rings, washer, and bearing from the pump shaft. Note: Do not remove the bearing unless it needs to be replaced. It is a press fit and will likely be damaged in the process of removing it. Note: Do not remove the bearing unless it needs to be replaced. It is a press fit and will likely be damaged in the process of removing it.
Transaxle Assembly and Adjustment Brake Interlock IMPORTANT: A clean working environment is essential during assembly of the transaxle. Otherwise, your rebuild efforts may not be successful. Note: Apply grease to packing before installation. Place the new packing (o-ring) and brake rod on brake arm. Apply a light film of grease into the hole of the upper case, then insert the brake arm into the upper case. Install the bushing, E-ring, and new packing (o-ring) on the brake shaft.
Connect the brake rod to the brake shaft. Place the washer on the brake rod and then attach the snap pin to the brake rod. Install the brake arm on the brake shaft. Make sure the word “UP” on the brake arm is visible. Figure 66 Drive the roll pin through the brake arm and brake shaft.
Neutral Adjust Eccentric Install the control shaft in the upper case and position the torsion spring as shown. Place new packing (o-ring) on the neutral adjust eccentric. Note: Apply grease to packing before installation. Figure 68 Apply a light film of grease into the hole on the upper case and insert the neutral adjust eccentric into the upper case. Figure 71 Drive the roll pin through the hydrostatic control arm and control shaft.
Pump Shaft Install the snap ring and the new seal onto the pump shaft. Install the bearing on the pump shaft. Note: Apply grease to the lip of the seal and place tape on the spline of the pump shaft to keep the seal lip from becoming damaged during installation. Install two washers and two snap rings on the pump shaft. Note: Make sure the snap rings are seated correctly in the pump shaft grooves. Figure 74 Figure 77 Insert the pump shaft into the upper case.
Pump Cylinder Block Assemble thin thrust plate, thrust bearing, and thick thrust plate to the swash plate. Place the snap ring and spring on the pump shaft. Note: Apply new oil to all parts prior to installation. Note: Be sure to place the thinner thrust plate at the bottom of the swash plate. Figure 80 Figure 82 Place the swash plate on the pump shaft. The shift blocks should be facing toward the slit found on the swash plate.
Install the cylinder block subassembly on the pump shaft. Note: Be sure to place the bearing retainer, which has the larger inner diameter, at the bottom of the housing. Figure 85 Figure 89 Motor Shaft Assemble the housing to the motor shaft. Install snap ring and spring on the motor shaft. Install the bearing, washer, and two snap rings on the motor shaft. Figure 86 Figure 90 Attach the new seal to the motor shaft.
Center Case Motor Shaft and Center Case Installation Install the two knock pins and shaft bushings in the center case, if removed. Oil contact surfaces of center case and cylinder blocks. Note: When installing the bushings, make sure they are seated correctly in the center case. Figure 95 Note: Be careful that no damage occurs to the center case surface during reassembly.
Install the motor shaft subassembly and center case subassembly in the case at the same time. Attach the two bypass actuating valves, springs, and push pins to the center case. Check push pin movement after assembly. Note: The motor housing is installed so the pistons are “in” at the top and “out” at the bottom. Make sure the pump cylinder block splines are aligned with the pump shaft. Compress the motor pistons into the cylinder block while aligning the center case with the mounting holes.
Differential Gear Axle Shafts and Differential Installation Attach the two differential pinions to the differential pinion shaft. Install new seal on the left and right axle shaft. Connect the differential pinion shaft to the final gear. Place the two thrust washers on the final gear. Figure 104 Note: Apply grease to the lip of each seal before installing and use tape on axle to protect seal from damage during installation. Figure 102 Attach the two differential side gears to the final gear.
Pinion Connect the differential gear assembly to the left and right axle shaft. Secure the bearing to the pinion shaft. Attach the shaft gear, washer, and bushing to pinion shaft. Figure 107 Install a retaining ring on the left and right axle shaft. Figure 110 Install the pinion shaft in the upper case. Note: Place the bushing on the end of the pinion shaft so that the flat surface of the bushing collar rests parallel to the top case surface.
Transaxle Case Join the lower case to the upper case. Torque Sequence You can significantly speed up the filling and bleeding process by adding oil to the upper case half before installing the lower half. To do this, plug the oil vent hose fitting. Secure the case so it does not move, and then fill it to half full with oil. 1 2 3 4 5 6 7 8 9 10 11 12 13 Thoroughly clean the mating surface of each case half.
Brake Install new packings (o-rings) on the pressure fill connector. Secure the brake drum to the motor shaft with retaining ring. Attach the connector to the center case through the lower case. (Install finger tight if planning to bleed air from transaxle before installing in tractor.) IMPORTANT: The brake drum must be free from oil or dust. Note: For quick air bleeding, apply new oil into the connector hole of the center case while rotating the pump and motor shaft by hand.
Attach the brake rod to brake arm. When inserting the rod (adjuster) into the hole on the brake cam lever, adjust the length of the rod to fit the brake arm hole. Note: Alternate oil—a synthetic oil (5W--50 or similar viscosity range) may be used in place of SAE 10W--30. This oil will permit an increase in the maximum operating temperature of approximately 18_F (10_C). Put the brake rod component onto the band brake and install the washer and cotter pin on the brake rod.
Use extreme caution while completing the following bleeding process. Loosen the locknut, B, and turn the eccentric, A, counterclockwise until the wheels start to rotate forward, C. Restart the engine and set at low idle speed. Turn the eccentric clockwise until the wheels begin to rotate in reverse, D. Depress the forward hydrostatic control pedal and push the tractor rearward.
Belts and Linkage Belt Replacement Note: Perform V-belt installation, routing, and inspection procedures from beneath the tractor. Remove the hydrostatic cross shaft support brackets from both footrests, C. Take out the four screws holding the tunnel cover in place. Remove the cover. Remove the far right pin only (the pin closest to the hydrostatic pedal), D, from the hydrostatic cross shaft. (Later models do not have pins.) Detach the belt tension spring, A.
Belt Routing—Bottom View The drive belt contacts a single V-idler pulley on the left side as it is routed from the engine pulley to the transaxle pulley. All three idler pulleys are mounted to the idler arm. Two pulleys are spring loaded; one is held in place with an eccentric. As it travels back from the transaxle pulley to the engine pulley, it passes between a pair of idler pulleys (a flat idler pulley and a V-idler pulley).
Belt Adjustment Remove the tunnel cover to check or adjust belt tension. For additional adjustment, turn the eccentric, C, on the eccentric mounted idler pulley, D. Loosen the back side idler pulley, A, and move it in the slotted mounting hole on the idler arm, B. Figure 127 A. Back side idler pulley B. Idler arm C. Eccentric Tuff Torq Model K61A Hydrostatic Transaxle D.
Figure 128 A. Fan B. Fan spacer C. Snap ring Belts and Linkage D. Pulley E.
Brake Linkage Foot Brake Description and Operation The action is then transferred to the trunnion, F, which connects the threaded brake rod to the control lever, E, on the transaxle, stopping the tractor. The foot and parking brake linkage consists of the following main components: Adjustment • Brake pedal Move the control lever, E, to its most rearward position and hold it there. • Brake lever Adjust the trunnion, F, on the brake rod, C, until it slips into the control lever, E.
Transaxle Brake Description and Operation brake drum, H, and the brake drum is splined to the hydrostatic motor output shaft, the tractor comes to a stop. Fig. 130 illustrates the main components of the transaxle brake. At the same time, the lobe, I, located on the brake lever acts upon the cam slot, J, profile of the swash plate control cam, K. This locks the hydrostatic control linkage in place (neutral position).
Brake Band Adjustment Loosen the rod, A, from the brake band assembly, B. Adjust the rod, A, until it slips easily into the hole in the brake band assembly actuator arm, D. Move the brake lever, C, to its most rearward position and hold it there. Figure 131 A. Rod B. Brake band assembly C. Brake lever Tuff Torq Model K61A Hydrostatic Transaxle D.
Hydrostatic Control Linkage Pedal Adjustment Description and Operation Remove the rear fender and seat assembly. The hydrostatic control pedal assembly has a forward and reverse pad and is fitted to the cross shaft, C, for rotation. One end of the control rod, D, is attached to the pedal assembly; the other end is attached to the transaxle control arm, E. The ends of the control rod are threaded. Take out the two fuel tank mounting bolts. Remove the tank and set it to the left side of the tractor.
Cruise Control Components Description and Operation The hydrostatic transaxle can be held at a desired speed with cruise control, standard equipment on some models. Its effect on the transmission system is described below. For electrical troubleshooting, refer to the Toro Riding Products Demystification Guide, form 492--4509. The cruise control is activated by a three-position rocker switch located on the right-hand side of the dash panel.
Bracket Magnet Relay The bracket which holds the magnet is secured to the frame by two bolts and locknuts. A fourth relay is added to the relay panel when cruise control is installed. The relay receptacle on the cruise wire harness attaches to the existing receptacle on the relay panel. Magnet The magnet is located on the spring post of the bracket. It is correctly seated when the tab is inserted through the bracket slot.
Troubleshooting Problem No drive Possible Cause Incorrect oil/oil level in unit Drive belt has failed, is worn, or tension is out of adjustment Push valve in push position Parking brake engaged Control pedal linkage Engine pulley or transmission pulley Hydrostatic filter plugged Push valve plunger, springs, or valve body Directional valves stuck or spring broken Damage to rotating groups or valve body Damaged pinion shaft or differential assembly No drive—one direction Control pedal bent or broken Contro
Problem Creeps in neutral Possible Cause Neutral adjustment eccentric out of position Control pedal bent or binding Control rod bent or binding Swash plate control lever pin damaged, bent, binding, or worn Swash plate cradle bearings failed, worn, or damaged Swash plate control arm ball and socket damaged or worn Neutral return spring failed, fatigued, or out of position Troubleshooting 42 Tuff Torq Model K61A Hydrostatic Transaxle
