14H and 16H Motor Graders Power Train Differential and Bevel Gear Caterpillar


Differential and Bevel Gear
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14H and 16H Motor Graders Power Train [RENR4174]
POWER TRAIN
CONTROL GP-DIFFERENTIAL LOCK
14H and 16H Motor Graders Power Train Differential and Bevel Gear



Illustration 1g00929870

Typical Example of a Differential and Bevel Gear

(1) Housing for the pinion shaft

(2) Differential housing

(3) Adjustment nuts (gear)

(4) Left side gear

(5) Clutch plates and discs

(6) Pinions (spider pinions)

(7) Bevel pinion shaft

(8) Bearings

(9) Spider shaft

(10) Bevel gear

(11) Adjustment nut (pinion)

(12) Thrust washers

(13) Shims

(14) Bevel gear and differential housing

(15) Right side gear

The differential is used to transfer power from the transmission output shaft to the final drives. The final drives then transfer power to the wheels. The differential allows the rear wheels to turn at different rates of speed. When the machine is turned, the differential allows the inside wheels to turn at a slower rate of speed than the outside wheels. The differential can be unlocked or locked by the operator. The differential lock control is located in the cab on the steering console in the cab.

On the 16H, the gear on the output shaft of the transmission turns the gear on the output shaft of the transfer gear. this sends power to bevel pinion shaft (7) .

On the 14H, the output shaft of the transmission directly turns bevel pinion shaft (7) .

Bevel pinion shaft (7) turns bevel gear (10), which is fastened to differential housing (2). The differential has spider shaft (9) for the pinions. The differential has two side gears: left side gear (4) and right side gear (15). The connections between the four pinions (6) and the two side gears are at right angles through a gear mesh. Left side gear (4) and right side gear (15) are connected to the shafts by splines which are connected to the final drives.

When the machine is moving straight in a forward direction and the differential is in the UNLOCK position, the same amount of traction is applied to the wheels on each side. The same amount of torque that is sent to each shaft for the final drive stops pinion (6) so the pinions cannot turn on spider shaft (9). This gives the same effect as if both tandem drives are being driven by the same shaft. When the machine is turned, different forces are applied to the opposite sides of the differential. This action will turn pinions (6). The rotation of pinions (6) allow the inside wheels to rotate at a slower rate of speed than the outside wheels. This moves the machine through the turn under full power.




Illustration 2g00929871

View of the Steering Column Inside the Cab

(16) Differential lock control switch

The differential can be locked by moving differential control switch (16) to the LOCKED position. This switch is located on the steering console in the cab of the machine. Moving switch (16) to the LOCKED position pressurizes the oil that is behind the piston. Locking the discs together forces the shaft to each final drive to turn together with the same speed. Moving switch (16) to the UNLOCK position releases the oil pressure behind the piston. This will allow the two output shafts to turn at different speeds.

The housing for the differential runs on tapered roller bearings. Pinions (6) turn on bronze bushings. Pinions (6), left side gear (4), and right side gear (15) turn against the thrust washers. The thrust washers take the end thrust against the differential housing.

The differential gets lubrication from oil that is thrown about inside the bevel gear housing. A flat surface on each shaft of spider shaft (9) allows lubrication to flow to pinions (6) and to the thrust washers.

Differential Lock Valve




Illustration 3g00929872

Differential Lock Valve

(17) Inlet opening

(18) Opening to the reservoir

(19) Opening to the clutch

Differential lock control switch (16) controls a solenoid activated hydraulic valve that is located on the differential carrier. When switch (16) is in the LOCK position, no current flows to the solenoid coil and the solenoid will not be energized. The valve is held open by spring force. The oil from the transmission relief valve flows through a hose to inlet opening (17). The internal passages of the solenoid valve act as an orifice.

Oil flows into inlet opening (17) and exits through opening (19) to the differential lock clutch. The oil flows into the differential through the differential cage assembly. Then, the oil flows to the cavity in the differential housing. The oil pushes the piston against clutch plates and discs (5) which causes left side gear (4) to turn with bevel gear (10). Pistons (6) do not turn on the spider shaft (9). Pistons (6) turn with left side gear (4) and right side gear (15) .

If the traction under the tandem wheels is different, the speed of the wheels will be equal.

When switch (16) is in the UNLOCKED position, current flows to the solenoid coil and the solenoid will be energized. The energized solenoid shifts the valve spool. The oil in the differential flows through opening (19) and flows into the oil reservoir. When traction varies under each wheel tandem, pinions (6), left side gear (4), and right side gear (15) can turn freely.

The differential lock control switch (16) can be engaged in any speed.

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