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Kubota BX1500, BX1800, BX1850 - Transmission
Kubota BX1500, BX1800, BX1850 - Transmission
System and Oil Flow
1 - Hydrostatic Transmission, 2 - Mid-PTO Assembly, 3 - Rear PTO
Assembly, 4 - Brake Assembly, 5 - Differential Gear Unit, 6 - Range Gear
Shift Unit, 7 - Front Wheel Drive Gear Unit, 8 - Hydraulic Pump Drive
Gear Unit
Oil Flow
1-Cylinder Block (Pump), 2-Swashplate, 3-Piston, 4-Cylinder Block
(Motor), 5-Check and High Pressure Relief Valve (Reverse), 6-Check and
High Pressure Relief Valve (Forward), 7-Power Take-Off Clutch Valve,
8-Charge Relief Valve, 9-Oil Filter Cartridge, 10-Power Take-Off Relief
Valve, 11-Oil Strainer, 12-Hydraulic Pump, 13-Transmission Case,
14-Power Steering, 15-Flow Priority Valve (Hydraulic Control Valve)
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 hydrostatic transmission 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 hydrostatic transmission housing. And overflow oil
from HST housing return to the transmission case.
Hydraulic Pump Drive Gear
1 - 19T Gear Shaft, 2 - 29T Idle Gear, 3 - Front Cover, 4 - 13T Gear, 5
- Hydraulic Pump, 6 - Clutch Shaft
The hydraulic pump (5) is mounted to front cover (3) of the transmission
case and driven by 13T gear (4) on the clutch shaft (6).
Kubota BX1500, BX1800, BX1850 - Brake Assembly
1-Brake Cam Lever LH, 2-Transmission Case, 3-Rear Axle LH, 4-Steel Ball,
5-Cam Plate LH, 6-Friction Plate, 7-Bearing Holder LH, 8-Rear Axle RH,
9-Axle Cover, 10-Brake Cam Lever RH, 11-Brake Disc, 12-Brake Pedal,
13-Parking Brake Lock Pedal, 14-Spring, 15-Brake Rod, 16-Turnbuckle
The mechanical wet disc brakes are used for right and left travelling
brakes. They are operated by the brake pedal (12) through the mechanical
linkages and provide stable braking and require little adjustment. The
brake body is incorporated in the transmission case (2) and axle cover
(9) filled with transmission oil. For greater braking force, four brake
discs (11) are provided at the right and left sides respectively, and
the friction plates (6) fixed to the transmission case (2) and axle
cover (9) are arranged between the brake discs (11).
Travelling Brake - When the brake pedal (12) is
depressed, the linkage causes the brake cam levers (1), (10) to turn
into the direction of arrow shown in the above figure. Therefore, the
cam plates also moves and rides on the steel balls set in the grooves of
the transmission case (2) and axle cover (9) to press the brake disc,
the rear axle (3), (8) are braked by the frictional force generated by
the cam plate and brake disc.
Parking Brake - When the parking brake is applied, the
brake pedal (12) locked by the parking brake lock pedal (13) to actuate
the brake mechanism same as a travelling brake.
Kubota BX1500, BX1800, BX1850 Tractor - Mid
and Rear PTO
1 - Clutch Shaft, 2 - 12T Gear Clutch, 3 - PTO Clutch Pack, 4 - Rear
Cover, 5 - Rear PTO Shaft, 6 - 11T Gear Shaft, 7 - PTO Select Gear, 8 -
26T Idle Gear, 9 - Mid-PTO Shaft, 10 - Idle Shaft, 11 - 22T Gear
Three kinds of power flow are selected by operating the PTO select lever
to shift the PTO select gear (7) on the 11T gear shaft (6).
Mid-PTO Position - PTO Clutch Pack (3) - 12T Gear Clutch - PTO Select
Gear (7) - 22T Gear (11) - 26T Idle Gear (8) - Mid-PTO Shaft (9).
Rear PTO Position - PTO Clutch Pack (3) - 12T Gear Clutch (2) - PTO
Select Gear (7) - 11T Gear Shaft (6) - Rear PTO Shaft (5).
Kubota BX1500, BX1800, BX1850 Transmission -
Checking And Adjusting
Adjusting Maximum Speed
1-Stopper Bolt (Reverse), 2-Speed Control Pedal, 3-Stopper Bolt
(Forward)
Depress the speed control pedal (2) all the way and lengthen the stopper
bolt (3) until it touches the bottom surface of the speed control pedal
(2). Release the speed control pedal (2) to the neutral, lengthen the
stopper bolt (3) half turn and lock it. Adjust the stopper bolt (1)
length “A” to 30 mm (1.18 in.) and lock it securely. Maximum Forward
Speed - 13.0 to 14.0 km/h (8.1 to 8.8 mph). Maximum Reverse Speed - 10.0
to 11.0 km/h (6.3 to 6.9 mph).
Preparation before HST Adjustment
1-Front Wheel, 2-Wooden Block, 3-Hydraulic Jack, 4-Rear Wheel, 5-Brake
Rod, 6-Speed Control Pedal, 7-Front Wheel Drive Lever, 8-4WD OFF
Position, 9-4WD ON Position, 10-Seat Belt, 11-Speed Control Pedal Link,
12-Speed Control Rod, 13-Trunnion Arm, 14-Neutral Arm, 15-Neutral
Spring, 16-Neutral Adjust Lever
Place the wooden blocks (2) at F and R side of wheels not to move the
tractor. Measure the speed control pedal (6) control force with a
pushpull gauge before starting the engine. Remove the brake rod (5)
because improper brake rod adjustment will cause the HST neutral
adjustment unexpectedly. Remove the neutral spring (15) from the neutral
arm (14). Move the neutral arm (14) by hand. Check that the neutral arm
(14) moves smoothly around the neutral adjust lever (16). If the neutral
arm (14) does not move smoothly around neutral adjust lever (16), apply
spray grease to neutral arm fulcrum contacted to the neutral arm (14).
Check it again. If the neutral arm (14) still does not move smoothly,
change the neutral arm (14) with a new one. Reinstall the neutral spring
(15) to the original position. Lift up the rear wheels (4) with safely
by the hydraulic jacks (3). Shift the front wheel drive lever (7) to
“OFF” position (8). To avoid the engine stopping in adjusting neutral
and to contact the operator’s seat switch, fasten firmly seat belt (10)
on the operator’s seat as shown in the figure. Speed control pedal
control force (forward side pedal) - 60 to 100 N (13.5 to 22.8 lbs).
Speed control pedal control force (reverse side pedal) - 40 to 80 N (9.0
to 18.0 lbs).
Adjustment of HST Neutral Position
1-Range Gear Shift Lever, 2-Hi Position, 3-NEUTRAL Position, 4-Lo
Position, 5-Neutral Adjust Lever, 6-Locking Screw, 7-Neutral Plate,
8-Rear Wheel, 9-Speed Control Pedal, 10-Neutral Spring, 11-Adjust Rod
Start the engine. Shift the range gear shift lever (1) to “Hi” position
(2). Loosen the locking screw (6). And push the neutral adjust lever (5)
toward the tractor rear side as shown in the figure until the rear
wheels (4) begin to rotate forward. Push the neutral adjust lever (5)
toward tractor front side until the rear wheels (4) stop rotating. When
the rear wheels (4) stop rotating, lock the neutral adjust lever (5)
with the locking screw (6). Depress the speed control pedal (9) forward
to rotate the rear wheels (8), release the foot from the speed control
pedal (9) and check that the rear wheels (8) stop rotating. Depress the
speed control pedal (9) reverse to rotate the rear wheels (8), release
the foot from the speed control pedal (9) and check that the rear wheels
(8) stop rotating. If the rear wheels (8) do not stop rotating, repeat
the above mentioned procedure 3 to 5 again and check that the rear
wheels (8) stop rotating at the neutral position of the speed control
pedal (9). Shift the range gear shift lever (1) to “LOW” position. Check
that the rear wheels (8) stop rotating at the neutral position of the
speed control pedal (9). Reinstall the brake rod to the original
position. Remove the hydraulic jacks. Disconnect the safety belt to
return the operator’s seat switch to the original condition (for only
model equipped Operator’s Presence Control System). Check the HST proper
operation on the usual jobs.
Kubota BX1500, BX1800, BX1850 Transmission -
Servicing Specifications
Charge Relief Valve (Setting Pressure) - 294.2 to 490.4 kPa 3.0 to 5.0
kgf/cm2 42.7 to 71.1 psi
Check and High Pressure Relief Valve (Setting Pressure) - 13.73 MPa 140
kgf/cm2 1991.2 psi
PTO Clutch (Operating Pressure) - 961 kPa 9.8 kgf/cm2 139.4 psi
Shift Fork to Shifter Gear Groove (Clearance) - 0.03 to 0.48 mm / 0.0012
to 0.019 in.
13T-25T Gear to Front Wheel Drive Idle Shaft - 0.007 to 0.043 mm /
0.0003 to 0.0017 in.
22T Gear to 11T Gear Shaft - 0.007 to 0.039 mm / 0.0003 to 0.0015 in.
12T Gear Clutch to Clutch Shaft - 0.007 to 0.037 mm / 0.0003 to 0.0015
in.
PTO Clutch Disc - 1.70 to 1.90 mm / 0.067 to 0.075 in.
Pressure Plate - 1.95 to 2.05 mm / 0.077 to 0.081 in.
Steel Plate - 1.15 to 1.25 mm / 0.045 to 0.049 in.
Clutch Piston Flatness - 0.15 mm / 0.0059 in.
Pressure Plate and Steel Plate Flatness - 0.20 mm / 0.0079 in.
Clutch Spring Free - 37.3 to 37.7 mm / 1.47 to 1.48 in.
PTO Brake Disc - 3.20 to 3.40 mm / 0.126 to 0.134 in.
Differential Case to Differential Side Gear - 0.050 to 0.151 mm / 0.0020
to 0.0059 in.
Differential Pinion Shaft to Differential Pinion - 0.080 to 0.122 mm /
0.0031 to 0.0048 in.
Differential Pinion to Differential Side Gear (Backlash) - 0.15 to 0.30
mm / 0.0059 to 0.0118 in.
Spiral Bevel Pinion Shaft Side (Clearance) - 0.1 to 0.3 mm / 0.0039 to
0.0118 in.
Spiral Bevel Pinion Shaft to Spiral Bevel Gear (Backlash) - 0.1 to 0.3
mm / 0.0039 to 0.0118 in.
Actuator and Bearing Holder (Flatness) – 0.30 mm / 0.0118 in.
Cam Plate and Ball - 22.89 to 22.99 mm / 0.9012 to 0.9051 in.
Brake Disc (Thickness) - 3.3 to 3.5 mm / 0.130 to 0.138 in.
Friction Plate - 1.92 to 2.08 mm / 0.0756 to 0.0819 in.
Kubota BX1500, BX1800, BX1850 Tractor -
Transaxle Separating
Draining Transmission Fluid
Place oil pan under the tractor. Remove the drain plugs at the bottom of
the transmission case. Drain the transmission fluid and reinstall the
drain plug. When refilling - Fill new oil from filling port after
removing the filling plug up to the upper notch on the dipstick. After
running the engine for few minutes, stop it and check the oil level
again, if low, add oil to prescribed level. Use only multi-grade
transmission oil. Use of other oils may damage the hydrostatic
transmission or hydraulic system. Never work the tractor immediately
after changing the transmission oil. Keeping the engine at medium speed
for a few minutes to prevents damage to the transmission. Do not mix
different brands oil together.
Speed Control Pedal, Lever Guides and Step
1-Lowering Speed Adjusting Knob, 2-Cutting Height Adjusting Dial Knob,
3-Lever Guide LH, 4-Step, 5-Lever Guide RH, 6-Speed Control Pedal,
7-Step Plate
Remove the lowering speed adjusting knob (1) and cutting height
adjusting dial knob (2). Remove the step plate (7), speed control pedal
(6) and lever guides (3), (5). Remove the step (4).
Fenders and Fuel Tank
Disconnect the lead wires from the tail lights. Remove the fuel cap,
then remove the fenders as a unit. Replace the fuel cap. Fuel Tank -
Drain the fuel. Disconnect the lead wire from fuel level sensor and fuel
hoses from the fuel tank. Remove the fuel tank stays and cushions, then
remove the fuel tank.
Lift Rod and Lower Link
1-Lift Rod RH, 2-Lower Link RH, 3-Lower Link LH, 4-Lift Rod LH,
5-Stopper Plate
Remove the lift rods (1) and (4). Remove the stopper plate LH (5), then
tap out the lower link pin to remove the lower links (2), (3) with check
chains as a unit.
PTO Cover, Fender Bracket, Hitch Plate and
Others
1-Upper PTO Cover, 2-PTO Cover RH, 3-Rear Support RH, 4-Hitch Plate,
5-Rear Support LH, 6-PTO Cover LH, 7-Fender Bracket RH, 8-Fender Center
Stay, 9-Fender Bracket LH
Remove the PTO covers (1), (2) and (6). Remove the hitch plate (4) and
rear supports (3), (5). Remove the fender brackets (7), (9), shim and
fender center stay (8). Do not firmly tighten all screws, bolts and nuts
until most components are attached. After the all screws, bolts and nuts
are tighten to the specified torque, install and secure the shim with
hexagonal socket head screw between fender brackets (7), (9) and fender
center stay (8). When tightening the upper PTO cover (1) mounting bolts
and nuts, adjust the operating force to 29.4 to 49.0 N (3.0 to 5.0 kgf,
6.6 to 11.0 lbs).
Kubota BX1500, BX1800, BX1850 - Transmission
Disassembly and Assembly
Transaxle Assembly
1 - Return Hose, 2 - Speed Control Rod, 3 - Power Steering Delivery
Hose, 4 - Differential Lock Rod, 5 - Pipe, 6 - Brake Rod LH, 7 - Nut, 8
- Brake Rod RH, 9 - Spring, 10 - Front Wheel Drive Shaft, 11 - Rear
Coupling Mounting Bolt, 12 - Wire Harness
Disconnect the speed control rod (2), differential lock rod (4) and
brake rod (6), (8). Remove the rear coupling mounting bolt (11) and
spring (9). Remove the nuts from the lift link rear (7) and wire harness
(12) clamps. Disconnect the power steering delivery hose (3). Disconnect
the return hose (1) and remove the pipe (5). Hold the transaxle assembly
with nylon strap and crane. Remove the transaxle assembly mounting
screws and separate it. Tighten the smaller screws (M12) first.
Parking Pedal, Propeller Shaft Assembly and
Tie-rod
1-Spring, 2-Parking Pedal, 3-Propeller Shaft Assembly, 4-Tie-rod,
5-Front Coupling, 6-Rear Coupling, 7-HST Fan
Unhook the spring (1) and remove the parking pedal (2). Disconnect the
front coupling (5) and remove the propeller shaft assembly (3). Remove
the HST fan (7) from propeller shaft assembly (3). Remove the tie-rod
(4). Apply grease to inside of the front coupling and rear coupling.
Brake Pedal, Speed Change Rod and HST Damper
1-Brake Pedal, 2-HST Damper, 3-Speed Change Rod, 4-Brake Arm, 5-Bush,
6-Spring
Remove the cotter pin and clevis pin, then remove the brake arm (4).
Remove the spring (6), brake pedal (1) and bushes (5). Remove the rue
rings, then remove the HST damper (2) and speed change rod (3).
PTO Clutch Assembly
Remove the PTO clutch assembly from transmission case. Apply
transmission oil to the seal ring on the clutch shaft.
Disassembling PTO Clutch Assembly
1 - Collar, 2 - Needle Bearing, 3 - 12T Gear Clutch, 4 - Bearing Collar,
5 - Clutch Spring, 6 - Spring Collar, 7 - External Snap Ring, 8 - Brake
Pressure Plate, 9 - External Snap Ring, 10 - Shim, 11 - External Snap
Ring, 12 - Brake Disc, 13 - Clutch Shaft, 14 - Clutch Case, 15 -
Pressure Plate, 16 - Internal Snap Ring, 17 - Clutch Piston, 18 - Clutch
Disc
Remove the collar (1), needle bearings (2) and 12T gear clutch. Remove
the external snap ring (9), then remove the shims (10), brake pressure
plate (8) and brake disc (12). Remove the external snap rings (11) and
(7). Remove the spring collar (6), clutch spring (5) and bearing collar.
Remove the internal snap ring (16), then draw out the pressure plates
(15) and clutch discs (18). Tap out the clutch shaft (13) and remove the
clutch piston (17) from clutch case (14). Apply transmission oil to the
O-rings, D-ring and seal ring, and take care not to damage it.
Axle Cover
Remove the rear bracket and front bracket. Remove the axle cover from
transmission case. Apply liquid gasket to joint face of the transmission
case to axle cover. Align the mounting surface of the front bracket,
rear bracket and axle cover to the transmission case before tightening
the bracket mounting nut.
Kubota BX1500, BX1800, BX1850 - Transmission
Service
Cylinder Block Assembly
1-Cylinder Block, 2-Piston, 3-Thrust Washer, 4-Spring, 5-Polished Face
Check the cylinder blocks (1) and pistons (2) for scratches and wear. If
scratch or worn, replace the cylinder block assembly. Check that the
piston (2), spring (4) and thrust washer (3) are in each cylinder bore.
Check the pistons for their free movement in the cylinder block bores.
If the piston or the cylinder block is scored, replace the cylinder
block assembly. Check the polished face (5) of cylinder block for
scoring. If scored, replace the cylinder block assembly.
Thrust Washer, Thrust Roller Bearing and
Thrust Plate
Check the thrust roller bearing for scratches and excessive wear. If
worn, replace. Check the thrust plate for scratches and excessive wear.
If worn or scored, replace.
Pump Shaft
1-Seal Surface, 2-Bearing Surface, 3-Ball Bearing
Check the seal surface (1), the bearing surface (2) and the ball bearing
(3). If the shaft is rough or grooved, replace it. If the ball bearing
is worn, replace it.
Needle Bearing and Oil Seal
Check the oil seals for damage. Check the needle bearings for wear. If
the oil seals and needle bearings are worn or damaged, replace them.
Clearance between Shift Fork and Shifter Gear
Groove (Range Gear Shift)
Insert the shift fork into the shifter gear groove and measure the
clearance with a feeler gauge. If the clearance exceeds the allowable
limit, replace it. Clearance between shift fork and shifter gear groove
0.03 to 0.48 mm (0.0012 to 0.019 in). Allowable limit - 0.7 mm (0.028
in).
Clearance between 13T-25T Gear and Front Wheel
Drive Idle Shaft
Measure the 13T-25T gear I.D. with a cylinder gauge, and then front
wheel drive idle 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 needle O.D. If the clearance exceeds the allowable limit,
replace it. Clearance between 13T-25T gear and front wheel drive idle
shaft - 0.007 to 0.043 mm / 0.0003 to 0.0017 in. Allowable limit - 0.10
mm / 0.0039 in. 13T-25T gear I.D. - 19.007 to 19.020 mm / 0.7483 to
0.7488 in. Front wheel drive idle shaft O.D. - 13.989 to 14.000 mm /
0.5507 to 0.5512 in. Needle O.D. - 2.494 to 2.500 mm / 0.0982 to 0.0984
in.
Clearance between 22T Gear and 11T Gear Shaft
Measure the 22T gear I.D. with a cylinder gauge, and then 11T gear 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 needle O.D. If
the clearance exceeds the allowable limit, replace it. Clearance between
22T gear and 11T gear shaft - 0.007 to 0.039 mm / 0.0003 to 0.0015 in.
Allowable limit - 0.10 mm / 0.0039 in. 22T gear I.D. - 24.007 to 24.020
mm / 0.9452 to 0.9457 in. 11T gear shaft O.D. - 19.987 to 20.000 mm /
0.7869 to 0.7874 in.
Clearance between 12T Gear Clutch and Clutch
Shaft
Measure the 12T gear clutch I.D. with a cylinder gauge, and then clutch
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 clutch I.D. and the sum of shaft O.D. and
two needle O.D. If the clearance exceeds the allowable limit, replace
it. Clearance between 12T gear clutch and clutch shaft - 0.007 to 0.037
mm / 0.0003 to 0.0015 in. Allowable limit - 0.10 mm / 0.0039 in. 12T
gear clutch I.D. - 22.007 to 22.020 mm / 0.8664 to 0.8669 in. Clutch
shaft O.D. - 17.989 to 18.000 mm / 0.7082 to 0.7087 in. Needle O.D. -
1.997 to 2.000 mm / 0.0786 to 0.0787 in.
PTO Clutch Disc Wear
Measure the thickness of PTO clutch disc with vernier calipers. If the
thickness is less than the allowable limit, replace it. Thickness of PTO
clutch disc - 1.70 to 1.90 mm / 0.067 to 0.075 in. Allowable limit -
1.55 mm / 0.061 in.
Pressure Plate and Steel Plate Wear
Measure the thickness of pressure plate and steel plate with vernier
calipers. If the thickness is less than the allowable limit, replace it.
Thickness of pressure plate - 1.95 to 2.05 mm / 0.077 to 0.081 in.
Allowable limit - 1.80 mm / 0.071 in. Thickness of steel plate - 1.15 to
1.25 mm / 0.045 to 0.049 in. Allowable limit - 1.10 mm / 0.043 in.
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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 |