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Kubota B1700, B2400 - Transmission and PTO

Kubota B1700, B2400 - Transmission Components

Main Gear Shift Section

1 - 2nd Gear Shaft with 13T, 13T and 18T Gear, 2 - 4th Shaft with 11T Gear, 3 - 30T Shifter Gear, 4 - 17T-13T Shafter Gear, 5 - 16T-20T Gear

Besides neutral, four kinds of power flow (from clutch shaft to 4th shaft) are available by operating the main gear shift lever to shift positions on the 30T shifter gear (3) and 17T-13T shifter gear (4) on the 4th shaft (2).

1st Position: 2nd Gear Shaft with 13T Gear (1) - 30T Shifter Gear (3) - 4th Shaft (2). 2nd Position: 2nd Gear Shaft with 13T Gear (1) - 17T-13T- Shifter Gear (4) - 4th Shaft (2). 3rd Position: 2nd Gear Shaft with 18T Gear (1) - 17T-13T Shifter Gear (4) - 4th Shaft (2). Reverse Position: 2nd Gear Shaft with 13T Gear (1) - 16T-20T Gear (5) - 30T Shifter Gear (3) - 4th Shaft (2).

Hi-Lo Gear Shift Section

Two kinds of power flow (from 4th shaft to spiral bevel pinion shaft) are available by operating the high-low gear shift lever to shift the gear on the spiral bevel pinion shaft. Low Position - 4th Gear Shaft - Shifter Gear - Spiral Bevel Pinion Shaft. High Position - 4th Shaft - Gear - Shifter Gear - Bevel Pinion Shaft.

Front Wheel Drive Section

2-wheel drive or 4-wheel drive is selected by changing the position of 20T shift gear with the front wheel drive lever. When the front wheel drive lever is set to "Disengaged," the 20T shift gear is neutral and power is not transmitted to the front wheel drive shaft. When the front wheel drive lever is set to "Engaged," the 20T shift gear slides to the right to engage with 13T gear on the spiral bevel pinion shaft. Therefore, the front drive shaft is actuated to drive the front wheels.

Kubota B1700, B2400 Tractor - Clutch

This tractor is used dry single plate type clutch. The clutch is located between the engine and transmission and is operated by stepping on the clutch pedal. When the clutch pedal is depressed, the clutch is disengaged and when it is released, the clutch is engaged and power from the engine is transmitted to the transmission.

1 - Clutch Disc, 2 - Pressure Plate Assembly, 3 - Release Bearing, 4 - Release Rod, 5 - Release Fork, 6 - Clutch Rod

Engine torque is transmitted to the pressure plate assembly via the flywheel (1) which is connected to the engine crankshaft. Therefore, the clutch cover constantly runs with engine. The clutch disc (10) is located between the flywheel (1) and the pressure plate (3) of pressure plate assembly. Torque is transmitted to the clutch disc (10) by the pressure created by diaphragm spring (4) installed in pressure plate assembly. Then, the torque is transmitted to the transmission via the clutch shaft (9). When the pedal (13) is depressed, the clutch release hub (7) and the clutch release bearing (6) move towards the flywheel and push the fingers of the diaphragm spring (4). In other words, this movement pulls the pressure plate (3) up and disengages the clutch.

Clutch Engaged

When the clutch pedal is not depressed, the clutch release bearing (6) and the fingers of diaphragm spring (4) are not connected to each other. Accordingly, the pressure plate (2) is tightly pressed against the flywheel (1) by the diaphragm spring (4). As a result, rotation of the flywheel (1) is transmitted to the transmission through the clutch shaft (8) due to the frictional force among the flywheel (1), clutch disc (10) and pressure plate (2).

Clutch Disengaged

When the clutch pedal is depressed, the clutch rod is pulled to move the clutch lever (11). Then, the release fork (9) pushes the release hub (7) and release bearing (6) toward the flywheel. Simultaneously, the release bearing (6) pushes the diaphragm spring (4). As the pressure plate (2) is pulled by the diaphragm spring (4), the frictional force among the flywheel (1), clutch disc (10) and pressure plate (2) disappears. Therefore, rotation of the flywheel (1) is not transmitted to the clutch disc (10), and then the rotation of the clutch shaft (8) stops.

Kubota B1700, B2400 Clutch - Checking And Adjusting

Clutch Pedal Free Travel

When checking, park the tractor on flat ground, apply the parking brake, stop the engine and remove the key. Slightly depress the clutch pedal and measure free travel at top of pedal stroke. If the measurement is not within the factory specifications, loosen the lock nut and adjust the clutch rod length. After adjusting it, be sure to keep the distance for stopper bolt. After adjusting them, try to start engine. If no start, check the safety switch setting position. Clutch pedal free travel - 20 to 30 mm (0.79 to 1.18 in).

Clutch Pedal Stopper Bolt

Measure the clearance between stopper bolt and clutch housing. If the measurement is not within the factory specifications, adjust it with the clutch pedal stopper bolt. After adjustment, secure the stopper bolt with the lock nut. Clearance between stopper bolt and clutch housing - 8.5 mm (0.33 in).

Safety Switch Setting Position

Measure the distance of safety switch when clutch pedal fully depressed. If the distance is not within the factory specifications, adjust the mounting position of safety switch. Safety switch distance - 17 to 21 mm (0.67 to 0.83 in).

Kubota B1700, B2400 Tractor - Power Take-Off

Rear-PTO Shift Section

Besides neutral, one kind of power flow are available by operating the PTO shift lever to shift positions of 17T shifter gear (2) for rear-PTO.

1 - 2nd Gear Shaft with 13T, 13T and 18T Gear, 2 - 17T Shifter Gear, 3 - 3rd Shaft, 4 - One-way Clutch, 5 - 5th Gear Shaft with 11T Gear, 6 - 24T Gear, 7 - Rear-PTO Shaft

Rear-PTO Shift Lever ON position

2nd Gear Shaft with 13T Gear (1) - 17T Shifter Gear (2) - 3rd Shaft (3) - One-way Clutch (4) - 5th Gear Shaft with 11T Gear (5) - 24T Gear (6) - Rear PTO Shaft (7)

Mid-PTO Section

Besides neutral, one kind of power flow are available by operating the PTO shift lever to shift positions of shifter (5) or 11T shifter gear (7) for mid-PTO.

1 - 2nd Gear Shaft with 13T, 13T and 18T Gear, 2 - 13T Gear, 3 - 19T Gear, 4 - 11T Gear, 5 - Shifter, 6 - One-way Clutch, 7 - Mid-PTO Shaft

Mid-PTO Shift Lever ON Position

2nd Gear Shaft with 18T Gear (1) - 13T Gear (2) - Clutch (6) - Mid-PTO Shaft (7) 19T Gear (3) - 11T Gear (4) - Shifter (5) - One-way Clutch

One-way Clutch Cam Section

1 - Clutch Cam for Rear PTO, 2 - Clutch Cam for Mid-PTO, 3 - Clutch Cam Spring, 4 - 3rd Shaft, 5 - 5th Gear Shaft, 6 - Mid-PTO Shaft

The one-way clutch cam is also called an overrunning clutch. It is composed of a pair of clutch cams (7), (8) and a cam spring (3). One of the clutch cam is splined to the shaft (6), and the other is splined to the shaft (5). These two clutch cams (1), (2) are engaged with each other by the force of the cam spring. As long as the shaft (4) is rotating faster than the shaft (5), (6) these two clutch cams (7), (8) will remain engaged, and the shaft (5), (6) is driven. But, if the PTO shaft drives a rotary mower as an implement, for example, and the source of power is stopped by pressing the clutch pedal, or if the engine speed is lowered, the clutch cam (7) will overrun as shown in the figure. This overrunning is caused by the inertia of the mower blades. Then, engagement will not take place until the shaft (4) is running faster than the shaft (5), (6). In this way, the one-way clutch cam protects the transmission and engine power train against damage, by allowing the PTO shaft and the shaft (5), (6) to overrun if PTO shaft over speeds.

Kubota B1700, B2400 - Differential Gear

Differential Function

During Straight Running - Rotation of the spiral bevel pinion is transmitted to the spiral bevel gear and differential case. When road resistance to the right and left wheels are equal, differential pinions and differential side gears are all rotate as a unit. Both rear axles received equal input, and both wheels turn at the same speed, allowing the tractor to go straight ahead. At this time, differential pinions do not rotate around the differential pinion shaft.

During Turning - When the tractor turns, the road resistance to the inside tire increases (as if braking is applied to that side only). In other words, if one of tires slows down, revolution difference is generated in the differential side gears. When rotation of one differential side gear becomes lower than the other, differential pinions begin rotating around differential increased in speed by the speed increment of differential pinion rotating around differential pinion shaft. This means that rotation of one rear axle is slowed down and that of the other rear axle is increased. Thus, the tractor turn smoothly without power loss. The combined number of revolutions of the right and left differential side gears is always twice that of the spiral bevel gear. When spiral bevel gear revolution is 100 rpm, and if one of the differential side gears stops moving, the revolution of the other differential side gear becomes 200 rpm and if one rotates at 50 rpm, the other rotates at 150 rpm.

Kubota B1700, B2400 Differential Lock

1 - Differential Pinions, 2 - Shift Fork, 3 - Differential Lock Lever, 4 - Differential Gear Shaft, 5 - Spiral Bevel Gear, 6 - Differential Pinion Shaft, 7 - Differential Case, 8 - Differential Lock Clutch, 9- Differential Gear Shaft

When resistance to the right and left tires are greatly different due to ground conditions or type of work, the tire with less resistance slips and prevents the tractor from moving ahead. To compensate for this drawback, the differential lock restricts the differential action and causes both rear axles to rotate as a unit. When the differential lock pedal is stepped on, it causes the differential lock lever (3) to rotate, which will move the shift fork (2) and the differential lock clutch (8) toward the spiral bevel gear (5). The differential lock clutch (8) engaged with the teeth of the differential case (7) to cause the differential case (7) and the differential lock clutch (8) to rotate as a unit. Therefore, differential pinions (1) are unable to rotate around differential pinion shaft (6) and identical revolutions are transmitted to the right and left differential gear shafts (4), (9).

Kubota B1700, B2400 - Transmission Case

Separating Hydraulic Cylinder and Rear Axle Case

1 - Rear-PTO Shift Lever, 2 - Aux. Speed Change Lever, 3 - Mid-PTO Shift Lever, 4 - Connecting Plate, 5 - Top Link Bracket, 6 - Hydraulic Cylinder Assembly, 7 - Drawbar Frame, 8 - Rear Axle Case, 9 - Connecting Pipe, 10 - Propeller Shaft, 11 - Universal Joint

Remove the connecting pipe (9) and propeller shaft (10). Tap out the spring pins and remove the universal joint with front wheel propeller shaft. Remove the external snap ring and remove the auxiliary speed change lever (2) with rod, rear-PTO shift lever (1) and mid-PTO shift lever (3). Remove the hook and connecting plate (4). Remove the top link bracket. Remove the hydraulic cylinder mounting screws and dismount the hydraulic cylinder assembly (6). Disconnect the differential lock rod. Remove the drawbar frame mounting screws and remove the drawbar frame. Remove the rear axle mounting screws and remove the rear axle case (8) from the differential case. Apply liquid gasket to joint face of the differential case and the rear axle case, differential case and the hydraulic cylinder.

Separating Main Shift Cover, Mid-PTO Case and Transmission Case

Remove the main shift cover mounting screws and separate the main shift cover with differential lock pedal. Remove the mid-PTO case mounting screws and separate the mid-PTO case from transmission case. Remove the rear-PTO cover mounting screws and separate the rear-PTO cover (couldn't draw out completely). Remove the transmission case mounting screws and nuts and separate the transmission case from differential case. Apply liquid gasket to joint face of the main shift cover, transmission case, differential case and mid-PTO case.

Front Cover

Remove the front cover mounting screws and remove the front cover. Apply liquid gasket to joint face of the front cover and transmission case.

4th Gear Shaft

Remove the bearing, 30T shifter gear and 13T-17T shifter gear. Draw out the 4th gear shaft with 19T gear rearward.

Spiral Bevel Pinion Shaft and 20T Shifter Gear

Remove the external snap ring and one-way clutch cam. Remove the spiral bevel pinion shaft with 13T-32T shifter gear, 13T gear, and shift fork with shift rod. Remove the external snap ring and remove the 20T shifter gear. When installing the spiral bevel pinion shaft, be sure to install the shim.

2nd Gear Shaft and Front Wheel Drive Shaft

Remove the 2nd gear shaft with bearing. Draw out the front wheel drive shaft with 16T-20T gear. When installing the needle bearing into the 16T-20T gear, apply transmission oil to the needle bearings.

Middle Shaft and 3rd Shaft

Tap out the middle shaft and remove the 19T gear with bearing. Draw out the 3rd shaft with 17T gear, 13T gear and shift fork with shift rod. When assembling the 19T gear, face the chamfer side to the rear. When installing the needle bearings into the 13T gear, apply transmission oil to the needle bearings.

Mid-PTO Shaft and One-way Clutch

1 - Mid-PTO Case Rear Cover, 2 - Bearing, 3 - Friction Plate, 4 - Brake Disc, 5 - Spring, 6 - External Snap Ring, 7 - Spring, 8 - One-way Clutch Cam, 9 - Spring, 10 - Ball, 11 - Shift Arm, 12 - Oil Seal, 13 - Internal Snap Ring, 14 - Mid-PTO Shaft, 15 - 11T Gear, 16 - Shifter, 17 - Needle Bearing

Remove the mid-PTO case rear cover mounting screws and separate the rear cover (1). Remove the bearing (2) and remove the friction plates (3), brake discs (4) and spring (5). Remove the external snap ring (6) and remove the spring (7) and one-way clutch cam (8). Remove the spring (9) and ball (10). Draw out the dowel pin and remove the shift arm (11) with shifter. Remove the oil seal (12) and internal snap ring (13). Remove the mid-PTO shaft (14) with bearing, 11T gear (15) and shifter (16). Apply grease to lip and outer of oil seal. When installing the needle bearings (17) into the 11T gear and one-way clutch cam, apply transmission oil to the needle bearings.

Main Gear Shift Fork

Remove the cotter pin and remove the spring and ball. Draw out the shift rod and remove the 1st-reverse gear shift fork. Remove the 2nd-3rd gear shift fork, in the same way as the 1st-reverse shift fork removing procedure. Take out the interlocker and slide the shift arm stopper and then remove the shim arm. Remove the shift shaft. When remove the differential lock pedal shaft draw out the dowel pin first.

Kubota B1700, B2400 Tractor - Transmission Case Servicing

Bearing Checking

While holding the inner race, push and pull the outer race in all directions to check for wear and roughness. Apply transmission oil to the bearing and hold the inner race. For needle bearing, lay the needle rollers to check for any damage and wear. Replace it if defects are found.

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. Clearance between shift fork and shift gear groove (Allowable limit) - 0.5 mm (0.020 in).

Clearance between Gear and Shaft

Measure the gear I.D. with a cylinder gauge, and then shaft O.D. with an outside micrometer. Measure the O.D. of two needles in the needle bearing with an outside micrometer. Clearance is the difference between the gear I.D. and the sum of shaft O.D. and two needles O.D. If the clearance exceeds the allowable limit, replace it. Clearance between FWD shaft and 16T-20T gear - 0.027 to 0.067 mm (0.0011 to 0.0025 in). FWD shaft O.D. - 21.967 to 21.980 mm (0.8648 to 0.8654 in). 16T-20T gear I.D. - 28.007 to 28.021 mm (1.1024 to 1.1032 in). Needle O.D. - 2.996 to 3.000 mm (0.1179 to 0.1181 in). Clearance between 13T gear and 3rd shaft - 0.007 to 0.046 mm (0.0003 to 0.0018 in). 3rd shaft O.D. - 21.987 to 22.000 mm (0.8656 to 0.8661 in). 13T gear I.D. - 28.00 to 28.021 mm (1.1026 to 1.1032 in). Needle O.D. - 2.994 to 3.000 mm (0.1179 to 0.1181 in). Clearance between 11T gear, one-way clutch cam and mid-PTO shaft - 0.020 to 0.026 mm (0.0008 to 0.0010 in). Mid-PTO shaft O.D. - 19.989 to 20.000 mm (0.7869 to 0.7874 in). 11T gear and one-way clutch I.D. - 24.007 to 24.020 mm (0.9452 to 0.9457 in). Needle O.D. - 1.997 to 2.000 mm (0.0786 to 0.0787 in).

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