Specifications, Service and Repair of Farm and Lawn Tractors

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Kubota B3030, B3000, B3300 - Transmission


Kubota B3030, B3000, B3300 - Hydrostatic Transmission Structure

Hydrostatic transmission is composed of variable displacement piston pump, fixed displacement piston motor and valve system.



1 - Cylinder Block (Motor), 2 - Piston, 3 - Thrust Collar, 4 - Motor Shaft, 5 - Retainer Plate, 6 - Thrust Collar, 7 - Pump Shaft, 8 - Variable Swashplate, 9 - Piston, 10 - Cylinder Block (Pump), 11 - Charge Relief Valve, 12 - Needle Bearing, 13 - Valve Plate

Front Case



1 - Flywheel, 2 - Clutch Housing, 3 - Steel Plate, 4 - Clutch Shaft, 5 - Oil Seal, 6 - Ball Bearing, 7 - Oil Seal, 8 - 28T-28T Front Wheel Drive Shaft 1, 9 - Front Wheel Drive Shaft 2, 10 - 24T Front Wheel Drive Shaft 3, 11 - Bi-Speed Turn Clutch, 12 - Front Mission Cover, 13 - Propeller Shaft, C - To HST, D - From Front Wheel Drive Gear Section

In Kubota B3030, B3000, B3300 tractor, clutch disk is not installed. The steel plate is installed on the clutch shaft. Power from the engine is transmitted through the steel plate to the clutch shaft and HST pump shaft.

Kubota B3030, B3000, B3300 - Hydrostatic Transmission Linkage

Bi-Speed Turn Linkage

Bi-Speed Turn lever is connected to the Bi-Speed rod and the Bi-Speed Turn ON/OFF shift shaft. The left bevel gear case of the front axle is connected to the front Bi-Speed Turn shift shaft with a Bi-Speed rod 2.



1 - Bi-Speed Rod 1, 2 - Front Mission Cover, 3 - Bi-Speed Turn ON/OFF Shift Shaft, 4 - Bi-Speed Turn Shift Shaft, 5 - Bi-Speed Rod 2, A - Connected to the Left Bevel Gear Case

Bi-Speed Turn Engaged

When the Bi-Speed Turn lever is shifted to “ON” position, the Bi-Speed rod 1 (1) is pushed down and the Bi-Speed Turn ON/OFF shift shaft (2) is rotated counterclockwise. It is kept ”ON”. When steering the steering wheel to “Left” or “Right”, the Bi-Speed rod 2 connected to the left bevel gear case is pulled. The Bi-Speed Turn shift shaft (3) is rotated. At this time, hydraulic oil from the pump port enter to the Bi-Speed clutch shaft through both the Bi-Speed Turn shift shaft (3) and the Bi-Speed ON/OFF shift shaft (2). The Bi-Speed Turn is engaged.

Bi-Speed Turn Disengaged

When the Bi-Speed Turn lever is shifted to “OFF” position, the Bi-Speed rod 1 (1) is pushed up and the Bi-Speed Turn ON/OFF shift shaft (2) is rotated clockwise. It is kept ”OFF”. When steering the steering wheel to “Straight”, the Bi-Speed rod 2 connected to the left bevel gear case is not pulled. The Bi-Speed Turn shift shaft (3) is kept to “OFF” position. At this time, hydraulic oil from the pump port does not enter to the Bi-Speed Turn ON/OFF shift shaft. The Bi-Speed Turn is disengaged.

Kubota B3030, B3000, B3300 - Cruise Control Linkage



1 - Return Spring, 2 - Cruise Control Lever, 3 - Cruise Lock 1, 4 - Release Rod, 5 - Roller, 6 - Neutral Holder, 7 - Trunnion Shaft, 8 - HST Pedal, 9 - HST Lever, 10 - Cruise Lock 2, 11 - Brake Rod, 12 - Cruise Rod, 13 - HST Plate, 14 - HST Lever, 15 - Brake Spring

Cruise Control “ON” Position

When depressing the HST pedal (8) to “Forward”, the HST lever (14), the cruise rod (12) and the cruise lock 2 (10) moves like the arrow shown in the pictures. And when the cruise control lever (2) is set to the desired position, the cruise lock (1) is locked to the cruise lock 2 (10) and the travelling speed is held to the desired speed.

Cruise Control “OFF” Position

When depressing the brake pedals (9), the release rod (4), the cruise control lever (2) and the cruise lock 1 (3) moves like the arrows shown in the pictures. And the cruise lock 1 release from the cruise lock 2 (10). Cruise lock is changed from “ON” to “OFF” position. Since the cruise lock is kept “OFF”, the neutral holder turns counterclockwise, and the roller is returned to “Neutral” position. The HST pedal (8) also returns to “Neutral“ position and the tractor stops.

Front Wheel Drive Section



1 - Front Wheel Drive Lever, 2 - Transmission Case, 3 - Shifter, 4 - Front Wheel Drive Shaft, 5 - 19T Shifter Gear, 6 - 14T Gear, 7 - 17T Gear, 8 - 25T-31T Gear, 9 - 6T Bevel Pinion Shaft, A - 4 Wheel Drive Position, B - 2 Wheel Drive Position, F - Power to Front Wheels, R - Power to Rear Wheels

Kubota B3030, B3000, B3300 Tractor - Hydraulic PTO Clutch

Rear PTO

When the PTO shift lever is set to "REAR PTO" (R) position, the PTO shift lever pushes the control rod. The control rod pushes the PTO shift arm. In this state, the PTO shift arm shifts the PTO shifter forward. The inner spline of the PTO shifter meshes the independent PTO shaft spline. Power is transmitted from the independent PTO clutch to the rear PTO shaft as follows. Independent PTO clutch - PTO shifter - Independent PTO shaft - Rear PTO shifter - Rear PTO shaft.

Rear PTO / Mid PTO

When the PTO shift lever is set to "REAR PTO / MID PTO" (R/M) position, the PTO shift lever pulls the control rod. The control rod pulls the PTO shift arm. In this state, the PTO shifter keeps its position between the independent PTO shaft spline and the 25T mid gear spline. In this position, the inner spline of the PTO shifter meshes both independent PTO shaft spline and the 25T and gear spline. Power is transmitted from the independent PTO clutch to both the rear PTO shaft and the mid PTO shaft as follows. Rear PTO Section: Independent PTO Clutch - PTO shifter - Independent PTO Shaft - Rear PTO shifter - Rear PTO shaft. Mid PTO Section: Independent PTO Clutch - PTO shifter - 25T mid gear - 26T gear on front wheel drive shaft - 17T-26T mid gear - 30T gear - Mid PTO shaft 17T.

Mid PTO

When the PTO shift lever is set to "MID-PTO" (M) position, the PTO shift lever pulls the control rod. The control rod pulls the PTO shift arm. In this state, the PTO shift arm shifts the PTO shifter reverse. The inner spline of the PTO shifter meshes the 25T Mid PTO gear spline. On the other hand, the range gear shifter arm turns the rear PTO control plate counterclockwise and turns the rear PTO arm counterclockwise. Since the rear PTO arm is turned counter clockwise, the rear PTO shifter is pushed forward. Then, the rear PTO shifter meshes the rib of the transmission case. In this state, the rear PTO brake shifter prevents the independent PTO shaft from rotating itself. Power is transmitted from the independent PTO clutch to the Mid PTO shaft as follows. Independent PTO clutch - PTO shifter - 25T mid gear - 26T gear - 17T-26T mid gear - 30T gear - Mid PTO shaft.

Kubota B3030, B3000, B3300 - Rear Axle

Removing Rear Wheels and Rear Axle

Support the tractor sub-frame with a jack. Remove the rear wheel mounting bolts and the nuts. Remove the rear wheel. Disconnect the brake rods. Remove the rear axle case mounting bolts. Remove the rear axle. Apply liquid gasket to the joint face of the rear axle case and the differential gear case.

Differential Lock Shift Fork

Remove the spring. Draw out the differential lock shift lock clutch and the differential lock shift fork. Remove the external cir-clip. Remove the transmission oil filter bracket.

Rear Axle Shaft

Remove the fork rod. Remove the ball bearing with a puller. Remove the gear. Remove the brake shaft assembly. Tap out the rear axle shaft with a rubber hammer to the outside. Tap in the ball bearing to the rear axle case.

Ball Bearing Checking

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 defect, replace it.

Kubota B3030, B3000, B3300 - HST Transmission Removal

Transmission Case Separating

Disconnect the brake rods. Disconnect the code bands from the wiring harness. Disconnect the couplers from the HST neutral switch and the PTO neutral switch. Separate the wiring harness from the transmission case. Loosen the pipe bands. Disconnect the hydraulic inlet pipe. Disconnect the independent PTO valve delivery pipe. Disconnect the hydraulic cylinder delivery pipe. Hoist the transmission case and the main frame. Support the transmission with a jack. Remove the main frame mounting bolts. Separate the transmission assembly from the main frame. After separating the transmission, remove the rear wheels and the transmission outer parts installed to the transmission.

HST Assembly

Remove the HST mounting bolts. Separate the HST assembly from the transmission. Install the O-ring to the transmission case. Apply liquid gasket to the groove of the transmission case.

Plate Push Rod, Neutral Arm and Neutral Holder

Remove the plate push rod. Remove the spring. Remove the neutral arm mounting bolt. Loosen the bolt of the neutral holder. Remove the neutral holder.

Center Section 1

Remove the center section mounting hex. bolts. Separate the HST housing from the center section. Use a new gasket. Install the poppet to the center section. Don't drop the spring. Check the knock pin. Hold the gasket with the hex. bolts not to drop the gasket.

Valve Plates

Pushing the valve plate against the anchor pin, lift the valve plate to remove. Remove the valve plate. Remove the valve plate. Install the groove the valve plates to the anchor pins securely.

Oil Seals and Needle Bearings

Remove the needle bearing. Remove the oil seals. After checking or changing the oil seals, apply the bearing with hydrostatic transmission oil and the oil seal with grease.

Check and High Pressure Relief Valve and Neutral Valve

Remove the valve plug with a hex. wrench. Remove the spring and the valve. Remove the neutral valve body. Remove the pin from the neutral valve body. Remove the plug with 2.5 mm hex. wrench. Push the neutral valve with 2.5 mm hex. wrench not to damage it. Take out the inner parts from the neutral valve body.

HST Housing Case Cylinder Blocks

Remove the cylinder blocks from the pump shaft and the motor shaft. Remove the cir-clip and spring from the cylinder block. Install the poppet to the center section, not to drop it. Install the spring to the HST housing side.

Piston and Retainer Plate

Remove the pistons with the retainer plates. Install the piston to its original position of the cylinder block. Check the direction of the thrust collar. If the direction of the thrust collar is wrong, HST will not be operated properly.

Motor Shaft and Pump Shaft

Remove the internal cir-clip from the HST housing. Remove the cover with an O-ring. Remove the motor shaft with the ball bearing from the HST housing. Remove the external cir-clip from the motor shaft. Remove the ball bearing from the motor shaft. Pump Shaft - Remove the internal cir-clip from the HST housing. Remove the oil seal from the HST housing. Remove the external cir-clip from the pump shaft. Remove the internal cir-clip from the HST housing. Remove the pump shaft to the cylinder block side. Replace the used oil seal with a new one.

Trunnion Shaft and Charge Relief Valve

Remove the internal cir-clip from the HST housing. Remove the internal cir-clip from the HST housing. Strike out the trunnion shaft slightly with a plastic hammer to the left side not to damage the o-rings. Take out the cover with o-ring. Take out the thrust collar using air blower. Check the O-rings for damage. Check the spring for breakage and wear. If it is unusual, replace it.

Kubota B3030, B3000, B3300 - Independent PTO Clutch

PTO Clutch Case

Remove the external cir-clip from the spline boss. Remove the internal cir-clip from the PTO clutch case. Remove the clutch disks and the clutch plates from the PTO clutch case. Remove the ball bearing from the PTO clutch case with a puller. When removing the cir-clip, use an adequate size snap ring pliers.

PTO Clutch Spring

Set the PTO clutch spring compressor to the PTO clutch case. Tighten the nut and remove the external cir-clip. Remove the spring collar and the PTO clutch spring.

PTO Clutch Disks and Brake

After removing the inner cir-clip from the PTO clutch case, remove the pressure plate. Remove the clutch disks and clutch plates. Remove the external cir-clip from the spline boss. Remove the brake plate, the brake disks and the brake plate. After removing the external cir-clip and the spring. Install the parts to the original positions.

Spline Boss Cir-clip

Push the cir-clip with a small screw driver through the small hole of the spline boss. Lift the cir-clip with a screw driver not to damage it. Install the cir-clip holding it by hands.

PTO Shaft

Remove the thrust bearing and the PTO shifter not to damage the seal rings located at the PTO shaft front side. Remove the seal rings located at the PTO shaft rear side. Remove the ball bearing with a puller. Check all seal rings. If the seal ring is damaged, replace it. Check the direction of the thrust bearing and install the thrust bearing.

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KUBOTA TRACTORS SPECIFICATIONS

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KUBOTA ENGINES DATA AND SERVICE SPECS

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KUBOTA FRONT END LOADERS

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KUBOTA TRACTORS TROUBLESHOOTING
L235 L2501 L2550 L275 L3110
L3301 L35 L3710 L3901 L4310
L5030 M4700 M5700 M6040 M6800
M8200 M8540 M9000 MX5100 MX5200