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Kubota B2301, B2311, B2231 - Transmission

Kubota B2301, B2311, B2231 - Transmission Assembly Parts

1-Cylinder Block (Motor), 2-Piston, 3-Thrust Collar, 4-Motor Shaft, 5-Thrust Ball Bearing, 6-Thrust Collar, 7-Pump Shaft, 8-Swashplate, 9-Piston, 10-Cylinder Block (Pump), 11-Charge Relief Valve, 12-Needle Bearing, 13-Valve Plate, 14-Cradle Bearing, 15-Check and High Pressure Relief Valve,

Range Gear Shift

1. Range Gear Shift Lever, 2. Range Shift Fork, 3. Range Shift Arm, 4. 6T Bevel Pinion Shaft, 5. 13T Gear (for Front Wheel Drive), 6. 14T-21T-29T Gear, 7. 23T-16T-14T Sub Shaft, L - LOW Range, M - MID Range, H - HIGH Range

Range gear shift lever (1) is located at left side fender. Range gear shift lever (1) can select three speed range, low speed, mid speed and high speed. Range gear shift lever (1) and 14T-21T-29T gear (6) are linked with range shift arm (3) and range shift fork (2) etc. Three range gear shifts are selected by shifting the 14T-21T-29T gear (6) on 6T bevel pinion shaft to 23T-16T-14T sub shaft (7).

Low Speed Position: 14T of 23T-16T-14T Sub Shaft (7) - 29T of 14T-21T-29T Gear (6) - 6T Bevel Pinion Shaft (4).
Middle Speed Position: 16T of 23T-16T-14T Sub Shaft (7) - 21T of 14T-21T-29T Gear (6) - 6T Bevel Pinion Shaft (4).
High Speed Position: 23T of 23T-16T-14T Sub Shaft (7) - 14T of 14T-21T-29T Gear (6) - 6T Bevel Pinion Shaft (4).

Front Wheel Drive Section

1 - Front Wheel Drive Lever, 2 - Front Wheel Drive Shaft, 3 - 20T Shifter Gear, 4 - 13T Gear, 5 - 6T Bevel Pinion Shaft, A - 4WD Position, B - 2WD Position, F - Power to Front Wheels, R - Power to Rear Wheels

Front wheel drive lever (1) is located at the right side fender. Front wheel drive lever (1) and shifter are linked. 20T shifter gear (3) is located on the front wheel drive shifter (2). 2-wheel drive or 4-wheel drive is selected by changing the position of 20T shifter gear (3) reverse or forward. When the font wheel drive lever (1) is set to "4 Wheel Drive" position, 20T shifter gear (3) slides forward, meshes the 13T gear (4) on the 6T bevel pinion shaft (5). In this state, power from the 6T bevel pinion shaft (5) is transmitted through 20T shifter gear (3) to the front wheel drive shaft (2) and the front wheels.

Kubota B2301, B2311, B2231 Tractor - Independent PTO

Independent PTO Clutch

1 - HST Pump Shaft, 2 - Independent PTO Clutch, 3 - Independent PTO Control Valve, 4 - HST Motor Shaft, 5 - Case, 6 - PTO Clutch Shaft, 7 - Seal, 8 - Bearing, 9 - Shifter, 10 - Clutch Discs and Plates, 11 - Brake Plate 4, 12 - Brake Disc, 13 - Brake Plate 2

Independent PTO clutch (2) is located behind the HST pump shaft (1) in the transmission case. Independent PTO clutch (2) is operated with pressured hydraulic oil forced from the independent PTO control valve (3). When independent PTO lever is shifted to "ENGAGED" position, hydraulic oil is forced through the transmission case inner passage (A) and PTO clutch shaft (6) to PTO clutch. In this state, power from HST pump shaft is transmitted through independent PTO clutch (2) to independent PTO clutch shaft (6). When independent PTO lever is shifted to "DISENGAGED" position, hydraulic oil is not forced to the PTO clutch. In this state, power from HST pump shaft (1) is not transmitted to independent PTO clutch shaft (6).

Independent PTO Control Valve Checking

Disconnect the OPC switch connector and remove the seat. Remove the plate. Remove the 3-point hitch lowering speed knob. Remove the plug with a hexagon wrench. Install the adapter to the independent PTO control valve. Connect the cable and the pressure gauge to the adapter. Reassemble the plate. Start the engine and set at the maximum speed. (Pressure at "ENGAGED" position) Move the independent PTO lever to "ENGAGED" position A. Measure the pressure. (Pressure at "DISENGAGED" position). Move the independent PTO lever to position B. Measure the pressure. If the pressure is not the factory specifications, adjust setting pressure with (the adjusting) shims. Independent PTO valve setting pressure (ENGAGED position) - 1.1 to 1.5 MPa (160 to 218 psi). Independent PTO valve setting pressure (DISENGAGED position) - 0 MPa (0 psi).

Kubota B2301, B2311, B2231 Independent PTO Troubleshooting

PTO Clutch Slip

Operating pressure is low - Check PTO control valve setting pressure. Inspect clutch disc or plate. Replace PTO clutch or other parts. Independent PTO control valve malfunctioning - Check PTO control valve setting pressure. Inspect or replace poppet or PTO control valve. Clutch disc or drive plate excessively worn - Check PTO control valve setting pressure. Inspect or replace clutch disc or plate. Deformation of piston or return plate - Inspect return plate or piston. Replace return plate or piston.

PTO Shaft Does Not Rotate

PTO clutch malfunctioning Solution order - Check PTO control valve setting pressure. Replace PTO clutch or other parts.

PTO Clutch Operating Pressure is Low

Transmission oil improper or insufficient - Check transmission oil. Relief valve malfunctioning - Replace poppet.

PTO Clutch Drags

Brake plate excessively worn - Replace brake plate. Return spring weaken or broken - Inspect or replace return spring.

Kubota B2301, B2311, B2231 Hydrostatic Transmission - Checking And Adjusting

Charge Relief Pressure

Remove the cover. Remove the plug from P1 port (reverse) or P2 port (forward). Install the adaptor to P1 port or P2 port. Install the cable and low pressure gauge to the adaptor. Start the engine and warm the oil before testing. Change the range gear shift lever to "NEUTRAL" position. Operate engine at the rated speed. Release the foot from the HST pedal. 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 the related hydraulic components. Low pressure gauge is 2.9 MPa (30 kgf/cm2, 427 psi) full scale. Charge pressure - 0.4 to 0.6 MPa / 60 to 80 psi. Checking port plug - 29 to 44 Nm / 21.7 to 32.5 lbf-ft.

High Pressure Relief Valve (Reverse)

Remove the cover. Remove the plug from P1 port (reverse). Install the adaptor to P1 port. Install the cable and high pressure gauge. Start the engine and warm the oil before testing. Check to see that parking brake is applied. Place the range gear shift lever to "HIGH" position. Operate the engine at the rated speed. Depress the rear side pedal of the HST pedal. Read the high pressure gauge to measure the high pressure relief valve pressure. If the measurement is not the same as factory specification, check the check and high pressure relief valve assembly. High pressure gauge is 40 MPa (400 kgf/cm2, 5800 psi) full scale. Oil temperature: 50 C (122 F). Check and high relief pressure - 23 to 25 MPa / 3400 to 3600 psi. Checking port plug - 29 to 44 Nm / 21.7 to 32.5 lbf-ft.

High Pressure Relief Valve (Forward)

Remove the cover. Remove the plug from P2 port (forward). Install the adaptor to P2 port. Install the cable and high pressure gauge. Start the engine and warm the oil before testing. Check to see that parking brake is applied. Place the range gear shift lever to "HIGH" position. Operate the engine at the rated speed. Depress the front side pedal of the HST pedal. Read the high pressure gauge to measure the high pressure relief valve pressure. If the measurement is not same as factory specification, check the check and high pressure relief valve assembly.

Kubota B2301, B2311, B2231 - PTO Clutch Case and Front Wheel Drive Shaft

Separating Transmission Case and PTO Clutch Case

1 - Transmission Case, 2 - Differential Case, 3 - PTO Clutch Case, 4 - PTO Brake Plate 4 Mounting Bolt, 5 - PTO Brake Plate 4, 6 - PTO Brake Plate 2, 7 - Transmission Case Groove, A - Position, B - Position

Remove the transmission case mounting bolts. Separate the transmission case from the differential case. Remove the PTO brake plate 4 mounting bolt. Install the PTO brake plate 4 to the transmission case groove securely.

Bevel Pinion Shaft

Remove the bevel pinion shaft assembly and range gear shaft assembly from the transmission case. Remove the spacer. Install the spacer to the transmission case. Install the bevel pinion shaft assembly and range gear shaft assembly. Transmission case mounting bolt (M10) and nut - 39.3 to 44.1 Nm / 29.0 to 32.5 lbf-ft. Hydraulic cylinder mounting bolt (M10) and nut - 39.3 to 44.1 Nm / 29.0 to 32.5 lbf-ft.

Sub Gear Shaft Assembly

Remove the circlip from the sub gear shaft. Remove the sub gear shaft assembly from the transmission case.

4WD Shaft

1.4WD Shaft, 2.Collar, 3.26T Gear, 4.Needle Bearing, 5.Collar, 6.Circlip, 7.Ball Bearing

Remove the circlip from the 4WD shaft. Remove the 4WD gear from the 4WD shaft. Remove the 4WD shaft with the 26T gear. Remove the 26T gear and the ball bearing.

4WD Shift Lever

Remove the bolt and the washer with rubber. Install the 4WD gear to the 4WD shaft. Install the 4WD shaft arm to the 4WD gear. Install the O-rings to the 4WD shift arm.

Kubota B2301, B2311, B2231 Tractor - Differential Gear Section

Rear Axle Case and Rear PTO Cover

Remove the rear axle mounting bolts. Remove the left rear axle case and the right rear axle case from the differential case. Remove the rear PTO cover mounting bolts and the rear PTO cover. Apply liquid gasket to the joint surface of the rear axles cases and the rear PTO cover.

Differential Bearing Holder (RH)

Remove the differential holder mounting bolts. Remove the differential holder and shims. 0.2 mm (0.008 in.) shim / 0.5 mm (0.020 in.) shim. Rear axle case (LH and RH) mounting bolt for aluminum material (M10) - 39.3 to 44.1 Nm / 29.0 to 32.5 lbf-ft. Rear PTO cover mounting bolt for aluminum material (M10) - 39.3 to 44.1 Nm / 29.0 to 32.5 lbf-ft. Differential bearing holder mounting bolt for aluminum material (M8) - 17.7 to 20.5 Nm / 13.1 to 15.1 lbf-ft.

Differential Gear Assembly

Remove the internal circlip from the differential case. Remove the shims. Remove the differential gear assembly from the differential case. When reassembling: 0.5 mm (0.020 in.), shim 0.6 mm (0.024 in.), shim 0.7 mm (0.028 in.), shim 0.8 mm (0.031 in.).

Differential Side Gear and Differential Pinion

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 B2301, B2311, B2231 Tractor - Hydrostatic Transmission Service

Pump Shaft

Pull out the pump shaft from the HST housing case. Check the oil seal surface, the bearing surface and the bearing. If the shaft is rough or grooved, replace it. If the bearing is worn, replace it.

Cylinder Block Face

Check the polished face of cylinder block for scoring. If scored, replace cylinder block assembly.

Valve Swash Plate Bearing Face

Check the swash plate bearing for scratches and excessive wear. If worn or scored, replace it. Apply liquid lock to the screw.

Thrust Collars, Thrust Ball Bearing and Swash Plate Surface

1-Thrust Collar, 2-Thrust Ball Bearing, 3-Swash Plate

Check the thrust collar for scratches and excessive wear. If worn or scored, replace it. Check the thrust ball bearing surface for scratches and excessive wear. If worn or scored, replace it. Check the swash plate for scratches and excessive wear. If worn or scored, replace it.

Thrust collars and Thrust Ball Bearing (Motor Side)

Check the thrust collars for scratches and excessive wear. If worn or scored, replace it. Check the thrust ball bearing for scratches and excessive wear. If worn or scored, replace it.

Center Section Oil Seals and Bearings

Check the oil seals for damage. Check the needle bearings for wear. If the needle bearings and oil seals are worn, replace all seals and needle bearings. After checking, coat the bearing with hydrostatic transmission oil and the oil seal lip with grease. Tightening torque: Screw (M3) - 1.5 Nm / 1.1 lbf-ft.

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.

Charge Relief Valve

1-HST Housing, 2-Spring, 3-Poppet, 4-Center Section

Check the spring for breakage and wear. If it is unusual, replace it.

Cylinder Block Bore and Pistons

Check the pistons for their free movement in the cylinder block bores. If the piston or the cylinder block bore is scored, replace cylinder block assembly. Do not interchange pistons between pump and motor cylinder block. Pistons and cylinder blocks are matched.

Kubota B2301, B2311, B2231 - Independent PTO Clutch Service

Checking Bearing

Hold the inner race, and push and pull the outer race in all directions to check for wear and roughness. Apply transmission fluid to the bearing, and hold the inner race. Then, turn the outer race to check rotation. If there is any problem, replace it. Valve plug - 59 to 78 Nm / 44 to 57 lbf-ft. Clearance between piston and bore - 0.02 to 0.03 mm / 0.0008 to 0.001 in.

Clutch Disc Wear

Measure the clutch disc thickness with vernier calipers. If the thickness is less than the allowable limit, replace it.

Steel Plate and Pressure Plate Wear

Measure the steel plate thickness with vernier calipers. Measure the pressure plate thickness with vernier calipers. If the thickness is less than the allowable limit, replace.

Piston Return Spring Free Length and Tension

Measure the free length of the piston return spring with vernier calipers. Place the piston return spring on a spring compression tester and compress to the specified length, and read the gauge. If the measurement is less than the allowable limit, replace.

KUBOTA TRACTORS TROUBLESHOOTING
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