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Kubota BX1880, BX2380, BX2680 - Transmission

Kubota BX1880, BX2380, BX2680 - Transmission Components

1. Hydrostatic Transmission, 2. PTO Clutch Section, 3. Range Gear Shift Section, 4. Front Wheel Drive Gear Section, 5. Mid-PTO Section, 6. PTO Gear Shift Section, 7. Rear PTO Section, 8. Differential Gear Section, 9. Brake Section, A. Front Side, B. Rear Side

Range gear shift lever (Hi-Lo)

1 - Range gear shift lever (Hi-Lo), A - Low, B - Neutral position, C - High

You can shift the range gear shift lever only when tractor is completely stopped. Do not force the range gear shift lever. If it is difficult to shift the range-gear-shift-lever into the neutral “N” position, you should attempt the following procedure. Depress the brake pedal firmly for several seconds. Without reducing the brake pedal force, shift the range gear shift lever.

If it is difficult to shift the range gear shift lever into the low position or the high position from the neutral “N” position, you should attempt the following procedure. Slightly depress the speed control pedal to rotate the gears inside of transmission. Release the speed control pedal to the neutral “N” position. Shift the range gear shift lever.

Front wheel drive lever

Use the lever to engage the front wheels with the tractor stopped. Shift the lever to the on position to engage the front wheel drive. To avoid damage of transmission, when the front wheel drive lever is not smoothly shifted, slightly depress forward or rearward on the speed control pedal.

Kubota BX1880, BX2380, BX2680 - Hydrostatic transmission oil flow

1. Cylinder Block (Pump), 2. Swashplate, 3. Piston, 4. Cylinder Block (Motor), 5. Check and High Pressure Relief Valve (Forward), 6. Check and High Pressure Relief Valve (Reverse), 7. High Pressure Relief Port Plug (Forward), 8. Charge Relief Valve, 9. High Pressure Relief Port Plug (Reverse), 10. PTO Clutch Valve, 11. PTO Relief Valve, 12. Oil Filter Cartridge, 13. Power Steering Controller, 14. Hydraulic Pump, 15. Flow Priority Valve (Hydraulic Control Valve), 16. Position Control Valve, 17. Oil Strainer, 18. Transmission Case, A. A Port, B. B Port, C. C Port, D. D Port

The pump and motor are joined in a closed hydraulic loop and most of oil circulates within the main oil circuit. A little oil lubricates and oozes out from the clearance between the moving parts of the case. Then oil in the main oil circuit of the HST needs to be supplied a want. The oil from the power steering circuit flows into the HST for charging. The charge oil aids smooth operation of pistons for pump and motor. The charge oil passes through the oil filter cartridge to charge relief valve port. The rest of oil passes through the charge relief valve into the HST housing. And overflow oil from HST housing return to the transmission case.

Kubota BX1880, BX2380, BX2680 - Speed set device

Speed set linkage

1 - Speed set rod, 2 - Speed control pedal, 3 - Cruise lock, 4 - Cruise lock, 5 - Cruise plate, 6 - HST pedal link, 7 - Speed change rod, 8 - Damper, 9 - Trunnion arm, 10 - Release plate, A - Speed set rod OFF, B - Speed set rod ON, C - Speed control pedal Forward, D - Cruise lock Locked

When the brake pedal is depressed, the release plate located under the brake pedal is pushed down. Since the cruise plate rotates, the cruise lock and between the cruise plate and the HST pedal link are released.

How to use the speed set device

1 - Speed control pedal, 2 - Stopper bolts, A - Forward, B - Reverse

To engage the speed set device - Accelerate speed to desired level using the speed control pedal. Push and hold the speed set rod downward to on position. Release the speed control pedal. Release the speed set rod. Desired speed will be maintained.

To disengage the speed set device - Depress the brake pedal. If you step on the speed control pedal on the forward acceleration side, the speed set device will disengage. The speed set device will not operate in reverse.

Kubota BX1880, BX2380, BX2680 Tractor - PTO System

PTO Clutch Engaged

1. HST Pump Shaft, 2. Clutch Gear, 3. Clutch Case, 4. Clutch Piston, 5. Clutch Plate, 6. Clutch Disc, 7. Spring, 8. Spline Boss, 9. O-ring, 10. Transaxle Case, 11. Brake Disc, A. From PTO Clutch Valve, B. Power to PTO Shaft, C. PTO Clutch Engaged

The oil from power steering controller flows into the PTO clutch valve. When the PTO clutch lever is set at the “Engaged” position, the PTO clutch valve rotates. Oil flows from the oil line through transmission case to the PTO clutch pack. Oil entering the clutch pack pushes the clutch piston (4) to engage the clutch pack. Power is transmitted from the HST pump shaft (1) through the PTO clutch to the clutch gear (2) and the PTO shafts.

PTO Clutch Disengaged

1. HST Pump Shaft, 2. Clutch Gear, 3. Clutch Case, 4. Clutch Piston, 5. Clutch Plate, 6. Clutch Disc, 7. Spring, 8. Spline Boss, 9. O-ring, 10. Transaxle Case, 11. Brake Plate, 12. Brake Disc, C. PTO Clutch Disengaged

When the PTO clutch lever is set at the “Disengaged” position, the PTO clutch valve closes the oil passage to the PTO clutch pack. The oil in the PTO clutch pack drain into the transaxle case (10). Thus the clutch piston (4) is pushed back by the spring (7). When the clutch piston (4) is pushed back by the spring (7), the brake plate (11) is also moved to contract the brake disc (12) so as to stop the rotation and drag of the PTO shafts.

Stationary PTO

1 - Seat lock lever, 2 - Seat, A - Unlock

To park the tractor and use the PTO system for chipper or pump, for example, start the PTO system in the following steps. Apply the parking brake and place blocks at the tires. Make sure that all shift levers are in their neutral position, and start the engine. Set the PTO select lever to the Rear-PTO (Rear only) position. Get off the seat and tilt up it. Move the seat lock lever behind the seat frame in the arrow direction in the following figure to release the seat lock, and lift the seat forward. 6. Set the PTO clutch lever to the on (engage) position. Set the engine speed appropriately to provide recommend rear PTO speed.

Kubota BX1880, BX2380, BX2680 - PTO select lever

Mid PTO

To use the mid PTO, shift the PTO select lever to the mid PTO position and the PTO clutch lever to the on position. The mid PTO is available for approved implements.

Mid-Rear PTO

To use the mid PTO and the rear PTO at the same time, shift the PTO select lever to the mid-rear PTO position and the PTO clutch lever to the on position.

Rear PTO

To use the rear PTO, shift the PTO select lever to the rear PTO position and the PTO clutch lever to the on position.

PTO drive shaft

1 - Inner and outer sliding profile tubes, 2 - Journal cross assy, 3 - Fitting yoke, 4 - Safety guard (in, out), 5 - Chain

When using a PTO drive shaft, read the operator's manual of the implement before operating the implement. If it is necessary for using the PTO drive shaft, adjust the length of it. Make sure that the PTO drive shaft is securely connected at both ends before operating it.

PTO clutch lever

The PTO clutch lever engages or disengages the PTO clutch which gives the PTO independent control. When you engage the PTO clutch, shift the PTO clutch lever slowly to avoid damage to the PTO clutch and implement. Shift the PTO clutch lever to the on position to engage the PTO clutch. Shift the PTO clutch lever to the off position to disengage the PTO clutch. The tractor engine will not start if the PTO clutch lever is in the engaged ON position. When you stand up from the seat with the PTO clutch lever at the engaged ON position, the engine will stop regardless of the position of the PTO select lever.

Adjusting the length of PTO drive shaft

To adjust the length of the PTO-drive-shaft, refer to the following instructions. To adjust the inner and outer guard tubes, hold the half shafts next to each other in the shortest working position, and mark the half shafts in the shortest working position of the inner and outer guard tubes. Shorten the inner and outer guard tubes to the marked position equally. Shorten the inner and outer sliding profile tubes by the same length as the inner and outer guard tubes. Round all sharp edges off, remove burrs, and grease sliding profiles.

Kubota BX1880, BX2380, BX2680 - Transmission Maintenance

Transmission fluid level check

1 - Oil inlet, 2 - Dipstick, A - Transmission fluid level is acceptable within this range

To check the transmission fluid level, check the dipstick as the following procedure. Draw out the dipstick. Wipe the dipstick clean. Replace the dipstick. Draw the dipstick out again. Check to see that the transmission fluid level lies between the two notches. If the fluid level is too low, add new fluid to the prescribed level at the oil inlet.

Transmission oil filter replacement

Remove the transmission oil filter. Put a film of clean transmission oil on rubber seal of new oil filter. Tighten the transmission oil filter quickly until it contacts the mounting surface. Tighten the transmission oil filter by hand an additional 1/2 turn only. After the new oil filter has been replaced, the transmission fluid level will decrease a little. Make sure that the transmission fluid does not leak through the seal, and check the fluid level. Check the dipstick and refill with oil to prescribed level. Properly dispose of used oil.

Transmission fluid changing

Transmission fluid capacity - 11.3 L. To drain the used transmission fluid, remove the drain plug at the bottom of the transmission case and drain fluid completely into the oil pan. After draining the transmission fluid, reinstall the drain plug. Clean the transmission strainer. Fill with new transmission fluid up to the upper notch on the dipstick. After running the engine for a few minutes, stop it and check fluid level again. If the transmission fluid level is lower, add it to the prescribed level. Properly dispose of used transmission fluid.

Transmission strainer cleaning

1 - Transmission strainer, 2 - Filter plate

When changing the transmission fluid, disassemble and rinse the transmission strainer with nonflammable solvent to completely clean off filings. When reassembling the transmission strainer, be careful not to damage the parts. Since the fine filings in the oil can damage the precision component parts of the hydraulic system, the end of the suction line is provided with an oil strainer.

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