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Kubota B7400, B7500, B7510, B7610 - HST Transmission

Kubota B7400, B7500, B7510, B7610 - Hydrostatic Transmission Components

1.Charge Relief Valve, 2.Check and High Pressure Relief Valve, 3.Trunnion Shaft, 4.Center Section, 5.Neutral Valve, 6.Fixed Displacement Piston Motor, 7.Housing, 8.Variable Displacement Piston Pump, 9.Charge Pump, 10.Input Shaft (Pump Shaft), 11.Output Shaft

Front Wheel Drive System

1 - Front Wheel Drive Shaft, 2 - Shifter Gear 20T, 3 - Spiral Bevel Pinion Shaft, 4 - Gear 13T

Kubota B7400, B7500, B7510, B7610 HST - Oil Flow

1.Oil Cooler, 2,16-Oil Filter, 3.Charging Pump, 4.Swash Plate, 5.Motor Cylinder Block, 6.Neutral Valve (Forward), 7.Neutral Valve (Reverse), 8.Piston, 9.Pump Cylinder Block, 10.Charge Relief Valve, 11.Oil Strainer, 12.Check and High Pressure Relief Valve (Forward), 13.Check and High Pressure Relief Valve (Reverse), 14.Power Steering Hydraulic Pump, 15.Main Circuit Hydraulic Pump, 17.Controller of Power Steering, 18.Hydraulic Control Valve, 19.Transmission Case

Kubota B7400, B7500, B7510, B7610 Hydrostatic Transmission - Control Linkage

1 - Speed Control Rod Assembly, 2 - Damper, 3 - Speed Control Pedal, 4 - Spring, 5 - Neutral Holder, 6 - Neutral Holder Arm, 7 - Roller, 8 - Neutral Adjuster, 9 - Trunnion Shaft

The speed control pedal (3) and the trunnion shaft (9) of variable swashplate are linked with the speed control rod (1) and the neutral holder (5). As the front footrest of the pedal is depressed, the swashplate rotates and forward travelling speed increased. Depressing the rear footrest increases reverse speed. The roller (7) on the neutral holder arm (6) is held with spring seats the detent of the neutral holder (5) so that the neutral holder returns to neutral. Then, the swashplate is returned to neutral with the neutral holder, when the pedal is released. The damper (2) connected to the speed control pedal restricts the movement of the linkage to prevent abrupt operation or reversing.

Kubota B7400, B7500, B7510, B7610 - HST Transmission Removal

Roll-Over Protective Structures (ROPS) and 3 Point Hitch

1.Lower Link, 2.3-Point Hitch Shaft, 3.ROPS Top Frame, 4.ROPS Frame, 5.PTO Shaft Cover, 6.Tail Lamp

Disconnect the wire harness of tail lamps. Remove the ROPS frame top (3). Remove the lower link (1) and the collar from the 3-point hitch shaft (2). Remove the both sides reflectors (6) with frame. Remove the both sides fender mounting screws. Remove the PTO shaft cover (5) and connecting plate. Remove the ROPS left, right frames and 3-point hitch shaft (2). Connecting plate mounting screw 47.1 to 56.9 Nm / 34.7 to 42.0 ft-Ibs. ROPS frame and frame top mounting bolt and nut 149.1 to 179.5 Nm / 109.9 to 132.4 ft-Ibs. ROPS frame mounting screw - 77.5 to 90.1 Nm / 57.2 to 66.5 ft-Ibs. 3-Point hitch shaft setting screw - 14.7 to 19.6 Nm / 10.8 to 14.5 ft-Ibs. 3-Point hitch shaft setting screw lock nut - 43.0 to 47.0 Nm / 31.7 to 35.4 ft-Ibs.

Seat, Fender, Steering Wheel, Panel, Step and Others

Remove the seat, seat adjuster, lowering speed adjusting knob, seat under cover and fender cover. Remove the position control lever grip, front wheel drive lever grip and bi-speed turn lever grip (Bi-speed Turn Type). Remove the fender RH. Remove the mid-PTO gear shift lever grip, rear PTO shift lever grip and range gear shift lever grip or Hi-Lo shift lever grip. Remove the fender LH. Loosen the lock nuts and disconnect the bi-speed turn cable (Bi-speed Turn Type). Remove the fender stay and bi-speed turn lever as a unit (Bi-speed Turn Type). Remove the cruise control lever grip, lever guide, tool box and fender stay. Remove the steering wheel, panel and panel under cover. Remove the fuel tank frame set screws and fuel tank stay. Remove the clutch and brake springs. Lift up the fuel tank frame and then remove the steps. Disconnect the speed set rod, HST release rod and brake pedal link. Place the jack under the transmission case, and then set the rigid rack under the rear axles. Remove the tires.

HST Pedal

1-Spring Stay, 2-Brake Rod RH, 3-Damper, 4-Speed Control Rod Assembly, 5-Speed Control Rod Screw, 6-Cruise Control Assembly,

Remove the brake springs and spring stay (1). Remove the brake rod RH (2). Remove the cruise control assembly (6). Remove the damper (3) and speed control rod assembly (4). Remove the HST pedal. Remove the speed control rod screw (5) from the neutral holder.

Sub Frame RH, HST Delivery Pipe and Hydraulic Pipes

Remove the sub frame RH. Remove the pips clamps and pipe joint bolt. Remover the HST safety switch holder with neutral rod. Disconnect the HST delivery pipe. Remove the brake rod RH. Remove the connecting pipe. Remove the HST suction pipe. Remove the sub frame RH. Remove the hydraulic oil filter assembly and pipes.

Separating Transmission Case from Center Frame and Hydrostatic Transmission

1-HST Delivery Pipe, 2-Universal Joint, 3-Front Wheel Propeller Shaft, 4-Neutral Spring, 5-Spring Holder, 6-Spring Hook

Separate transmission case and center frame. Remove the propeller shaft, front wheel drive shaft (1) and HST delivery pipe (2). Remove the neutral spring (4) and remove the spring holder (5). Separate the HST from transmission case. Apply liquid gasket (Three Bond 1208D or equivalent) to joint face of the HST and transmission case. When inserting the spring pins, face their splits in the direction at a right angle to the universal joint and propeller shaft. Apply grease to the spline of the HST pump shaft, front wheel propeller shaft, universal joint and ball coupling. Spring holder mounting screw 39.2 to 44.1 Nm / 28.9 to 32.5 ft-Ibs. HST and center frame mounting screw and nut - 62.8 to 72.6 Nm / 46.3 to 53.5 ft-Ibs.

Separating Hydraulic Cylinder, Rear Axle Cases and Others

Remove the front wheel drive lever. Remove the differential lock pedal support. Remove the top link bracket LH and remove the hydraulic cylinder. Remove the rear axle case and drawbar frame. Apply liquid gasket to joint face of the differential case to hydraulic cylinder and rear axle cases.

Separating Mid-PTO Case, Transmission Case and Differential Case

Remove the mid-PTO case mounting screws and separate the mid-PTO case and transmission case. Remove the transmission case mounting screws and nuts and separate the differential case and transmission case with middle case as a unit. Apply liquid gasket (Three Bond 1208D or equivalent) to joint face of the transmission case and differential case.

Kubota B7500HST, B7510HST, B7610HST - Transmission Checking And Adjusting

Adjusting Neutral

Disengage the front wheel drive lever (Drive only rear wheels). Lift the rear of the tractor so that the rear wheels are off the ground and run the engine at low idling and drive only rear wheels. Slightly loosen the neutral adjuster setting screw. Rotate the neutral adjuster clockwise so that rear wheels turn reverse. Then rotate it counterclockwise until wheels stop completely. Put a mark on the center frame aligning the groove on neutral adjuster. Rotate the neutral adjuster counterclockwise so the rear wheels turn forward. Then rotate it clockwise until wheels stop completely. Put a mark on the center frame aligning the groove on neutral adjuster. Hold the neutral adjuster so its groove is at the middle of the marks and tighten the setting screw. When the wheels tend to turn forward, rotate neutral adjuster clockwise. When the wheels tend to turn reverse, rotate neutral adjuster counterclockwise.

Charge Relief Pressure and High Relief Pressure

1-Neutral Valve (Forward), 2-Neutral Valve (Reverse)

Remove the lowering speed adjusting knob and dipstick, then remove the seat under cover. Assemble the HST adaptor A and threaded joint with O-ring and back up ring. Charge Relief Pressure - Remove the neutral valve assembly one side (forward (1) or reverse (2)) then install the assembled HST adaptor A to its neutral valve port. Install the cable and low pressure gauge to HST adaptor A. Change the range gear shift lever to Low position. Start the engine and run it at the maximum speed. Read the low pressure gauge to measure the charge relief pressure. If the measurement is not same as factory specification, check the charge relief valve and related hydraulic components. High Relief Pressure - Remove the neutral valve assembly forward (1), then install the assembled HST adaptor A to its neutral valve port. Install the cable and high pressure gauge to HST adaptor A. Change the range gear shift lever to High position. Start the engine and run it at the maximum speed. Depress the speed control pedal forward and read the high pressure gauge to measure the forward high relief pressure. Stop the engine and change the installation of HST adaptor A and pressure gauge from forward neutral valve port to reverse. Start engine and repeat above method (4. and 5.) to measure the reverser high relief pressure. If the measurement is not same as factory specification, check the high pressure relief valve and related hydraulic components. Charge relief pressure (Oil temperature at 50C) - 500 to 800 kPa / 73 to 116 psi. High relief pressure (Oil temperature at 50C) - 30.9 to 31.9 MPa / 4480 to 4622 psi. Tightening torque: Neutral valve cap screw - 58.8 to 68.6 Nm / 43.4 to 50.6 ft-Ibs.

Neutral Valve Actuation Test

Disengage the front wheel drive lever. Disconnect the brake rod, one side. Lift the rear of tractor, one side. Set the engine speed to 1500 rpm. Shift the range gear shift lever to Hi position. Move the HST pedal from the forward to the neutral position make sure that the tire comes to stop. Check the same way for the movement from rearward to the neutral position. In this time, make sure that the neutral range of HST. If the tire fail to stop or neutral range is point, check the each neutral valve.

Kubota B7500HST, B7510HST, B7610HST - Differential Gear Case Disassembly

PTO Shaft

Remove the PTO cover mounting screws and remove the PTO cover assembly. Apply liquid gasket (Three Bond 12080 or equivalent) to joint face of differential gear case and PTO cover.

Differential Gear Assembly

Remove the bearing holder mounting screws and remove the bearing holder. Take out the differential gear assembly. Install the differential gear assembly, noting the number of shims in the differential case left side and bearing holder side.

Spiral Bevel Gear

Remove the spiral bevel gear UBS screws. Remove the spiral bevel gear from differential case. Apply liquid lock to the spiral bevel gear UBS screws.

Differential Side Gear and Differential Pinion

1-Differential Pinion, 2-Differential Side Gear, 3-Dowel Pin, 4-Differential Pinion, 5-Shim

Put parting marks on the differential pinion and the differential side gear. Tap out the dowel pin. Remove the differential pinion shaft. Remove the differential pinion, differential side gear and shim. Install the differential pinion and differential side gear, aligning the parting marks.

Kubota B7400, B7500, B7510, B7610 - Hydrostatic Transmission Service

Valve Plate

Check the engagement of the valve plate and the anchor pin. Pushing the valve plate against the anchor pin, lift it to remove. Check the valve plate for foreign particles. Clean the valve plate and dry with compressed air. Check the valve plate for scratches, wear and erosion. If worn or scored, replace. After checking, coat them with hydrostatic transmission oil.

Thrust Plate and Swashplate

Check the thrust plate for scratches and excessive wear. If worn or scored, replace. Check the bearing surface of trunnion shaft (swashplate) for scratches and excessive wear. If worn or scored, replace.

Trunnion Shaft Cover

Check the bearing for scratches and excessive wear. If worn or scored, replace. Check the oil seal and the O-rings for damage. After checking, coat the bearings with hydrostatic transmission oil, and the oil seal lip and the O-rings with grease.

Oil Seals and Bearings for Shaft

Remove the internal snap ring and check the oil seals for damage. Check the bearings for wear. If the bearings are worn, replace. After checking, coat the bearing with hydrostatic transmission oil and the oil seal lip with grease.

Check and High Pressure Relief Valve

Check the valve plug and valve for scratches and damage. Check the valve seat in the port block for damage. Check the spring for breakage and wear. If anything unusual, replace the check and high pressure relief valve assembly.

Neutral Valve

Check the holes of the valve body and the neutral valve for clogging. If clogged, open hole with compressed air. Check the O-rings and the backup ring for scratches and damage. Check the springs for breakage and wear. If the valve surface is scored, replace. If anything unusual, replace

Kubota B7500HST, B7510HST, B7610HST - Differential Gear Service

Clearance between Differential Case (Spiral Bevel Gear) and Differential Side Gear

Measure the differential side gear boss O.D. with an outside micrometer. Measure the differential case I.D. and the spiral bevel gear I.D. with an inside micrometer, and calculate the clearance. If the clearance exceeds the allowable limit, replace faulty parts. Clearance between differential case (spiral bevel gear) and differential side gear - 0.025 to 0.066 mm (0.00098 to 0.00260 in). Differential case I.D. - 32.000 to 32.025 mm (1.25984 to 1.26082 in). Spiral bevel gear I.D. - 32.000 to 32.025 mm (1.25984 to 1.26082 in). Differential side gear O.D. - 31.959 to 31.975 mm (1.25823 to 1.25886 in).

Clearance between Differential Pinion Shaft and Differential Pinion

Measure the differential pinion shaft O.D. with an outside micrometer. Measure the differential pinion I.D. with an inside micrometer, and calculate the clearance. If the clearance exceeds the allowable limit, replace faulty parts. Clearance between differential pinion shaft and differential pinion - 0.016 to 0.045 mm (0.00063 to 0.00177 in). Differential pinion I.D. - 16.000 to 16.018 mm (0.62992 to 0.63063 in). Differential pinion shaft O.D. - 15.973 to 15.984 mm (0.62886 to 0.62929 in).

Backlash between Differential Pinion and Differential Side Gear

Secure the differential case with a vise. Set the dial indicator (lever type) with its finger on the tooth of the differential side gear. Press differential pinion and side gear against the differential case. Hold the differential pinion and move the differential side gear to measure the backlash. If the backlash exceeds the allowable limit, adjust with differential side gear shims. Backlash between differential pinion and differential side gear - 0.1 to 0.3 mm (0.004 to 0.012 in). Allowable limit - 0.4 mm (0.016 in).

Backlash between Spiral Bevel Pinion and Spiral Bevel Gear

Set the dial indicator (lever type) with its finger on the end of spiral bevel pinion. Move the spiral bevel pinion back and forth to each end and measure the side clearance. If the side clearance exceeds the factory specifications, adjust with the shims at front end of spiral bevel pinion. Set the dial indicator (lever type) with its finger on the tooth surface of bevel gear. Measure the backlash by fixing the spiral bevel pinion and moving bevel gear by hand. If the backlash exceeds the factory specifications, adjust with the shims at bearing holder and differential case. Adjust the backlash properly by repeating the above procedure.

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