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Kubota B2601, B26, B26TLB - Transmission

Kubota B2601, B26, B26TLB Hydrostatic Transmission - Front Case

In Kubota B2601, B26, B26TLB tractors, clutch disc is not installed. The input flange (3) is installed on the clutch shaft (4). Power from the engine is transmitted through the input flange (3) to the clutch shaft (4) and HST pump shaft.

1-Flywheel, 2-Clutch Housing, 3-Input Flange, 4-Clutch Shaft, 5-Ball Bearing, 6-Circlip, 7-Oil Seal, 8-Circlip, 9-Front Drive Shaft, 10-O-ring, 11-Circlip, 12-Ball Bearing, 13-O-ring, 14-Universal Joint, 15-Rear Drive Shaft

Kubota B2601, B26, B26TLB HST - Speed Set Linkage

Speed Set

1-HST pedal, 2-Lever, 3-Speed Set Lever, 4-Speed Set Holder, 5-Brake Pedal, 6-Tooth

The speed set device mainly consists of HST pedal holding section and HST pedal releasing section. When the HST pedal (1) is see to the desired position, the lever (2) turns counter clockwise. The speed set lever (3) to the "ON" position. The speed set holder (4) turns counter clockwise. On the other hand, sine lever engage with tooth (6) of speed set holder (4), the HST pedal (1) is held at the desired set position until the brake pedals (5) will be depressed by an operator.

Speed Set Release

1-HST pedal, 2-Lever, 3-Speed Set Lever, 4-Speed Set Holder, 5-Brake Pedal, 6-Brake Link

The speed set release is done by depressing the brake pedals (5). When an operator depresses the brake pedal (5), the brake link (6) is pushed by the brake pedals (5). When brake link (6) is pressed, the speed set holder (4) is released. If you step on the HST pedal on the forward acceleration side, the speed set device will disengage.

Kubota B2601, B26, B26TLB Hydrostatic Transmission - Checking And Adjusting

Readjustment of Relief Valve (When the HST does not work due to its loose hexagon socket head screw)

Measure the pre-adjustment Relief Valve Length. Compress the spring of the relief valve with a relief valve assembling tool. Then, find the Relief Valve Length by turning the poppet with a screwdriver. The Relief Valve Length changes by about 0.5 mm (0.0197 in.) per one turn of the poppet. Repeat the same operation a few times to find the Relief Valve Length as it is difficult to acquire at the first time. After finding the Relief Valve Length, hold the setscrew to a vice and fasten the hexagon socket head screw with specified torque. On this occasion, use a copper plate, etc. for the vice jaws not to damage the setscrew. Install the relief valve in Kubota B2301, B2601, B26, B26TLB HST. Check the relief pressure. The Relief Valve Length is for refresh only. Make sure to check the relief pressure after readjustment. If the relief pressure does not fall within the readjustment pressure range, repeat the processes of the above item 1 onward. Tightening torque Hex. socket head screw - 24.5 to 29.5 Nm / 18.1 to 21.7 lbf-ft. Relief valve readjusting pressure - 23 to 25 MPa / 3400 to 3600 psi. Relief Valve Length Reference value 38.5 to 38.6 mm / 1.516 to 1.519 in.

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 operate Kubota B2301, B2601, B26, B26TLB engine at low idling and drive only rear wheels. Slightly loosen the neutral adjuster setting screw. Rotate the neutral adjuster clockwise so the 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.

Kubota B2601, B26, B26TLB - Dismounting the Step and Floor Seat

HST Pedal, Floor Mat and Front Cover

Remove the HST pedal mounting bolts. Remove the HST pedal. Remove the lower adjusting knob. Remove the front cover. Remove the floor mat. ROPS - Disconnect the tail light connectors and turn signal light connectors. Remove the tail lights. Remove the spring pins. Remove the bolt. Remove the upper frame from lower frames. Remove the ROPS mounting bolts and the lower frames.

Seat and Fenders

Remove the seat and the lever grips. Disconnect the electrical socket connector. Remove the fender LH. Remove the fender RH. Remove the both side steps and seat under cover. Disconnect the seat switch connector. Remove the seat support.

Hydraulic Pipes and Others

Remove the clamps. Disconnect the suction pipe and delivery pipe. Disconnect the loader valve pipes. Disconnect the independent PTO pipe. Remove the right side brake rod and sub frame. Remove the left side brake rod and sub frame. Disconnect the HST pedal switch connector. Remove the frame support plate and spring. Remove the HST damper and plate. Front loader valve pipe joint - 48 to 70 Nm / 36 to 51 lbf-ft. 3-point hitch delivery pipe joint bolt - 48 to 70 Nm / 36 to 51 lbf-ft. Frame support plate mounting bolt (M12) - 64 to 74 Nm / 48 to 54 lbf-ft. Sub frame mounting bolt (M12) - 80 to 90 Nm / 59 to 66 lbf-ft. Sub frame mounting bolt (M14) - 126 to 150 Nm / 93.0 to 110 lbf-ft. Sub frame mounting bolt (M10) - 40 to 45 Nm / 30 to 34 lbf-ft.

Kubota B2601, B26, B26TLB - Front Case and HST Disassembly and Assembly

Clutch Housing

1.Bolt, 2.Engine Rear-End Plate, 3.Front Case, 4.Groove (for liquid gasket), A.Front Case Corner

Support the engine securely. Remove the front case mounting bolts. Remove the front case from engine. Front case mounting nut for aluminum material (M8) - 17.7 to 20.5 Nm / 13.1 to 15.1 lbf-ft. Front case mounting bolt for aluminum material (M10) - 39.3 to 44.1 Nm / 29.0 to 32.5 lbf-ft.

Clutch Shaft and Ball Bearing

Remove the oil seal. Remove the circlip. Remove the clutch shaft from the front case.

Kubota B2601, B26, B26TLB Hydrostatic Transmission Assembly

1.HST Assembly, 2.HST Assembly Mounting Bolt, 3.O-ring, 4.Groove (for Liquid Gasket)

Remove the HST mounting bolts. Separate the HST assembly from the transmission. Install the O-ring to the transmission case. Tightening torque HST assembly mounting bolt (M10, aluminum) - 39.3 to 44.1 Nm / 29.0 to 32.5 lbf-ft.

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

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. Do not drop the spring. Check the knock pin. Hold the gasket with the hex. bolts not to drop the gasket.

Oil Seals and Needle Bearings

Remove the needle bearing. Remove the oil seals. Center section mounting hex. bolt (M10, aluminum) - 49 to 59 Nm / 37 to 43 lbf-ft.

Check and High Pressure Relief Valve

Remove the valve plug with a hex. wrench. Remove the spring and the valve.

HST Housing Case Cylinder Blocks

1.Cylinder Block (Pump), 2.Pump Shaft, 3.Motor Shaft, 4.Cylinder Block (Motor), 5.Spring, 6.Poppet

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

Piston and Spring

Remove the pistons with the spring. Install the piston to its original position of the cylinder block.

Motor Shaft and Pump Shaft

1.Pump Shaft, 2.Circlip, 3.Oil Seal, 4.Circlip, 5.Motor Shaft

Remove the circlip and oil seal from the HST housing. Remove the circlip from the pump shaft. Remove the pump shaft. Remove the motor shaft. Replace the used oil seal with a new one.

Trunnion Shaft

Remove the circlip and oil seal from the HST housing. Remove the circlip from the trunnion shaft. Remove the swash plate. Strike out the trunnion shaft slightly with a plastic hammer and remove the trunnion shaft. Charge Relief Valve - Remove the spring and poppet. Check the spring for breakage and wear.

Kubota B2601, B26, B26TLB - Independent PTO Clutch and Mid-PTO

Installing PTO Clutch Shifter

Install the spring and the ball to transmission. Push the ball by finger from the inside of the transmission case. Push the PTO shift arm ball guide into the transmission case. Push the PTO shift arm ball guide with the PTO shift arm. Install the PTO cotter to the PTO shift arm. Align the PTO cotter to the groove of the PTO shifter.

PTO Clutch Case

1 - Ball Bearing, 2 - PTO Clutch Case, 3 - Brake Plate 4, 4 - Brake Plate 2, 5 - PTO Clutch Shaft, 6 - Thrust Bearing, 7 - PTO Shifter, 8 - 25T Mid PTO-gear, 9 - Clutch Disc, 10 - Clutch Plate

Remove the external circlip from the spline boss. Remove the internal circlip from the PTO clutch case. Remove the clutch discs and the clutch plates from the PTO clutch case. Remove the ball bearing from the PTO clutch case with a puller. When removing the circlip, use an adequate size circlip pliers.

PTO Clutch Spring

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

PTO Clutch Discs and Brake

1.Clutch Piston, 2.Clutch Plate, 3.Clutch Disc, 4.Spline Boss, 5.Pressure Plate, 6.Internal Circlip, 7.Spring Collar, 8.External Circlip, 9.Ball Bearing, 10.PTO Clutch Case, 11.Circlip, 12.Ball Bearing, 13.Brake Plate, 14.PTO Brake Disc, 15.Brake Plate, 16.External Circlip, 17.Bearing Collar, 18.Spring

After removing the inner circlip from the PTO clutch case, remove the pressure plate. Remove the clutch discs and clutch plates. Remove the external circlip from the spline boss. Remove the brake plate, the brake discs and the brake plate. After removing the external circlip and the spring.

Spline Boss Circlip

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

PTO Shaft

1 - PTO Clutch Shaft, 2 - Ball Bearing, 3 - 26T Mid-gear, 4 - PTO Shifter, 5 - Seal Ring, 6 - Thrust Bearing, 7 - Needle Bearing, 8 - Collar

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.

Mid-Gear and Idle Shaft

Remove the idle shaft from the transmission case using a screw driver. Remove the mid-gear from the transmission case. Remove the ball bearings and the internal circlip from the mid-gear. Install the internal circlip to the inner groove of the mid-gear.

Mid-PTO Case and Mid-Gear Shaft

Remove the mid-PTO case mounting bolts. Remove the mid-PTO case from the transmission case. Remove the mid-PTO oil seal from the mid-PTO case using a screw driver not to damage it. Remove the internal circlip. Remove the mid-gear shaft with the ball bearings. Remove the bearing from the mid-gear shaft. If the mid-PTO oil seal is damaged, worn or scratched, replace it. Apply grease to the lip and the outer of the mid-PTO oil seal. After installing the mid-gear, apply liquid gasket to the joint surface of transmission case and the mid-PTO case.

Kubota B2601, B26, B26TLB HST - Transmission Case Servicing

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. Clutch disc wear - 1.70 to 1.90 mm / 0.067 to 0.075 in. Steel plate wear - 1.15 to 1.25 mm / 0.045 to 0.049 in. Pressure plate wear - 1.95 to 2.05 mm / 0.0768 to 0.0807 in. Piston / return spring free length - 44.0 mm / 1.73 in. Piston return spring tension: 638.7 N / 26 mm, 143.6 lbf / 1.02 in.

Clearance between Shift Fork and Shift Gear Groove

Insert the fork into the shift gear groove and measure the clearance with a feeler gauge. If the clearance exceeds the allowable limit, replace it.

Differential Gear

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 damage parts.

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 damage parts. Clearance between shift fork and shift gear groove - 0.10 to 0.35 mm / 0.004 to 0.014 in. Clearance between differential case (spiral bevel gear) and differential side gear - 0.025 to 0.066 mm / 0.0010 to 0.0026 in. Differential case I.D - 32.000 to 32.025 mm / 1.2598 to 1.2608 in. Spiral bevel gear I.D - 32.000 to 32.025 mm / 1.2598 to 1.2608 in. Differential side gear O.D - 31.959 to 31.975 mm / 1.2582 to 1.2589 in. Clearance between differential pinion shaft and differential pinion - 0.048 to 0.084 mm / 0.0019 to 0.0033 in. Differential pinion I.D - 16.032 to 16.050 mm / 0.63119 to 0.63188 in. Differential pinion shaft O.D - 15.966 to 15.984 mm / 0.62859 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. Thickness of shims: 0.80 mm (0.0315 in.), 1.00 mm (0.0394 in.), 1.20 mm (0.0472 in.). Backlash between differential pinion and differential side gear 0.1 to 0.3 mm / 0.004 to 0.0012 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. Movement of spiral bevel pinion shaft at shaft directions - 0 mm / 0 in. Backlash between spiral bevel pinion and spiral bevel gear - 0.10 to 0.30 mm / 0.0039 to 0.0012 in.

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