Introduction

NOTE: For Specifications with illustrations, make reference to the POWER TRAIN SPECIFICATIONS for 910 WHEEL LOADER, Form No. REG01252. If the Specifications in Form REG01252 are not the same as in the Systems Operation and the Testing and Adjusting parts of this book, look at the printing date on the back cover of both books. Use the Specifications given in the book with the latest date.

Power Flow

POWER TRAIN
1. Diesel engine. 2. Torque converter. 3. Transmission. 4. Drive shaft. 5. Rear differential. 6. Transfer gears. 7. Front differential.

Power from the diesel engine (1) goes directly to the torque converter (2) through the engine flywheel. The output shaft of the torque converter is the same as the input shaft of the transmission (3). The four clutches are hydraulically activated. There are three stationary clutches and one turning clutch in the transmission. The four clutches give three forward and one reverse speed through manual selection.

The output gear of the transmission sends power to the input gear of the transfer gears (6). Power goes through the transfer gears to the output shaft of the transfer gears. Yokes and universal joints on both ends of the output shaft send power to the front and rear differentials (5) and (7). The bevel gear and bevel pinion of each differential sends power to the axles. The axles are fastened to the sun gears of the final drives. The final drives send power to the wheels.

Torque Converter, And Transmission

The transmission has a torque converter and a planetary transmission that gives three speeds forward and one speed reverse. The four clutches in the planetary group are hydraulically activated and each speed selection is done manually.

The torque converter is connected to the input end of the transmission. The converter is connected to the inside of the flywheel with splines. Output torque from the converter goes in the planetary transmission through a turning clutch and/or a sun gear. Only one clutch is engaged for each speed.

Torque Converter

The oil for the torque converter comes from the transmission pump. A relief valve controls the oil flow to the converter. This valve is in the pressure control valve.

Restrictions in the oil cooler controls the pressure from the outlet of the torque converter.

The spider, turning housing (8), impeller (2), and the drive gear for the oil pump (3) turn as a unit at engine speed.

Oil, from the hydraulic controls, goes in the converter through inlet (4). The action of the impeller is similar to a pump. The flow of oil inside the converter is:

From the impeller (2) to the turbine (6).From the turbine (6) to the stator (9).From the stator (9) back to the impeller (2).

Splines make the connection between the turbine (6) and the output shaft (5). The stator (9) is fastened to a flange. The flange is fastened to the transmission.

An outlet passage (7) in the carrier lets the oil out of the converter. The oil goes through the oil cooler to the lubrication system of the transmission.

The flow of oil, caused by the movement of the impeller, turns the turbine and the output shaft. During normal operation, the oil goes through the converter against a minimum of restriction, hitting each blade at a small angle. When the machine is working against a load, the speed of the turbine become slower, and the oil hits the blades at a more direct angle. This multiplies the torque sent to the output shaft.

TORQUE CONVERTER
1. Spider. 2. Impeller. 3. Drive gear for the pump. 4. Oil inlet. 5. Output shaft. 6. Turbine. 7. Oil outlet. 8. Turning housing. 9. Stator. AA. Drive assembly. BB. Driven assembly. CC. Stationary assembly.

The output shaft (5) of the torque converter turns the input shaft of the transmission.

Planetary Transmission

The planetary transmission has four clutches, No. 1, No. 2, No. 3 and No. 4 and the carriers for the planet gears. The No. 1 clutch is for THIRD SPEED. The No. 2 clutch is for SECOND SPEED. The No. 3 clutch is REVERSE SPEED. The No. 4 clutch is for FIRST SPEED.

All components inside the planetary transmission turn when the controls are in FIRST, SECOND, THIRD or REVERSE SPEED. Only those components that have been made dark are used in the flow of power through the transmission.

PLANETARY TRANSMISSION

1. Manifold.

2. Rotating housing.

3. Hub.

4. Housing for No. 2 clutch.

5. No. 2 clutch.

6. Sun gear.

7. Ring gear for No. 3 clutch.

8. No. 3 clutch.

9. No. 1 carrier.

10. No. 2 carrier.

11. No. 4 clutch.

12. Ring gear for No. 4 clutch.

13. Planet gear.

14. Planet gear.

15. Housing for No. 4 clutch.

16. Output gear.

17. Transmission shaft.

18. No. 1 clutch.

19. Ring gear for No. 2 clutch.

20. Planet gear.

21. Planet gear.

22. Sun gear.

The following components are always used in all speeds including REVERSE:

Sun (input) gear (22).Output gear (16).Planet carrier (9) and (10).Transmission shaft (17).

See the Power Flow Chart for the specific components that are used in each given speed.

POWER FLOW IN FIRST SPEED; NO. 4 CLUTCH ENGAGED

POWER FLOW IN SECOND SPEED; NO. 2 CLUTCH ENGAGED

POWER FLOW IN THIRD SPEED; NO. 1 CLUTCH ENGAGED

POWER FLOW IN REVERSE; NO. 3 CLUTCH ENGAGED

Lubrication System

LUBRICATION SYSTEM SCHEMATIC
1. Oil screen. 2. Lubrication relief valve. 3. Hydraulic controls. 4. Oil pump. 5. Torque converter. 6. Transmission reservoir. 7. Oil cooler.

The oil that is necessary for the operation and lubrication of the transmission is made available by a gear type pump (4). The gear that drives the pump (4) is fastened to the impeller housing of the torque converter (5) and turns at engine speed. The rotation of the pump is one and one half of engine speed.

The oil reservoir (6) for the transmission is in the bottom of the transmission case. The oil is pulled through a screen (1) by the pump (4). The pump (4) oil goes to the hydraulic controls (3).

TRANSMISSION LUBRICATION

Valves in the hydraulic controls (3) send oil to the clutches in the transmission and to the torque converter (5). From the torque converter (5) oil goes through the oil cooler (7) and then through the lubrication relief valve (2) to the reservoir (6).

Transmission Hydraulic Control

TRANSMISSION CONTROLS IN NEUTRAL AND ENGINE IS NOT RUNNING
1. Transmission reservoir. 2. Neutralizer signal valve. 3. Neutralizer safety valve. 4. Oil screen. 5. Oil pump. 6. Modulating relief valve. 7. Load piston. 8. Lubrication relief valve. 9. Relief valve for converter inlet. 10. Check valve. 11. Modulating orifice. 12. Check valve. 13. Line for lubrication. 14. Oil cooler. 15. Torque converter. 16. Spool valve. A. Pressure tap, P3, for converter inlet. B. Pressure tap for pump. C. Plug (must be removed while checking primary pressure). D. Pressure tap, P1, for clutches. E. Pressure tap for lubrication.

The following list gives a description of the functions of the valves of the transmission controls:

The major parts of the oil system for the hydraulic controls are: transmission reservoir (1), oil filter (4) oil pump (5), hydraulic valves (2), (3), (6), (7), (8), (9) and (10), torque converter (15) and oil cooler (14). The only valve that is outside the transmission case is the neutralizer signal valve (2).

The controls are fastened to a transmission clutch housing in the transmission. The valve spool (16) lets oil go to the clutch to engage it for the selection of speed. Pressures in the system are controlled by the modulating relief valve (6).

When the transmission is in NEUTRAL and the machine is not running, the positions of the valves are as shown in the schematic, TRANSMISSION CONTROLS IN NEUTRAL AND ENGINE IS NOT RUNNING.

TRANSMISSION CONTROLS IN NEUTRAL AND ENGINE IS RUNNING
1. Transmission reservoir. 2. Neutralizer signal valve. 3. Neutralizer safety valve. 4. Oil screen. 5. Oil pump. 6. Modulating relief valve. 7. Load piston. 8. Lubrication relief valve. 9. Relief valve for converter inlet. 10. Check valve. 11. Modulating orifice. 12. Check valve. 13. Line for lubrication. 14. Oil cooler. 15. Torque converter. 16. Spool valve. A. Pressure tap, P3, for converter inlet. B. Pressure tap for pump. C. Plug (must be removed while checking primary pressure). D. Pressure tap, P1, for clutches. E. Pressure tap for lubrication.

When the machine is started and the transmission is in NEUTRAL, the oil and the valves move as follows:

From the oil reservoir (1) to the oil screen (4).From the oil screen (4) to the oil pump (5).

After the oil leaves the pump (5) it goes in two separate directions. Some of the oil goes to the modulating relief valve (6) and on to the torque converter (15). Relief valve for torque converter inlet (9) keeps the pressure of the oil to the converter below 85 ± 15 psi (6.0 ± 1.1 kg/cm²). The remainder of the oil goes to the neutralizer safety valve (3) where it again goes in two separate directions. From the neutralizer safety valve (3), part of the oil goes to the neutralizer signal valve (2). The rest of the oil goes on to the load piston (7) and the spool valve (16). The spool valve (16) lets oil go to and from the clutches through the passages in its body.

The load piston (7) is all the way to the right against the cover. The check valve (12) is all the way to the left and the drain is open permitting only primary pressure of 60 psi (4.2 kg/cm²) maximum in the system. This only happens when a shift is made, or when plug (C) is removed.

TRANSMISSION CONTROLS IN FIRST SPEED FORWARD
1. Transmission reservoir. 2. Neutralizer signal valve. 3. Neutralizer safety valve. 4. Oil screen. 5. Oil pump. 6. Modulating relief valve. 7. Load piston. 8. Lubrication relief valve. 9. Relief valve for converter inlet. 10. Check valve. 11. Modulating orifice. 12. Check valve. 13. Line for lubrication. 14. Oil cooler. 15. Torque converter. 16. Spool valve. A. Pressure tap, P3, for converter inlet. B. Pressure tap for pump. C. Plug (must be removed while checking primary pressure). D. Pressure tap, P1, for clutches. E. Pressure tap for lubrication.

When a shift is made into FIRST FORWARD, the pressure in the system goes down and the force of the springs move the modulating relief valve (6) all the way to the left and the load piston (7) is moved to the right. When the modulating relief valve (6) moves to the left, flow to the torque converter is stopped. As the clutches fill, pressure in the system goes up. When the pressure of the oil becomes higher than the force of the spring, the oil again goes to the torque converter. The check valve (12) is in a position to close the passage, behind load piston (7), that lets oil go back to the oil reservoir (1). As the system pressure goes higher, the load piston (7) moves to the left and the force of the spring on the modulating relief valve is higher. The pressure goes higher gradually, and time in relation to psi, is modulation.

The orifice before the neutralizer safety valve (3) only lets 3 U.S. gpm (11.3 lit/min) oil go to the clutches and the remainder goes to the torque converter.

TRANSMISSION CONTROLS IN FIRST FORWARD WITH NEUTRALIZER VALVE ACTIVATED
1. Transmission reservoir. 2. Neutralizer signal valve. 3. Neutralizaer safety valve. 4. Oil screen. 5. Oil pump. 6. Modulating relief valve. 7. Load piston. 8. Lubrication relief valve. 9. Relief valve for converter inlet. 10. Check valve. 11. Modulating orifice. 12. Check valve. 13. Line for lubrication. 14. Oil cooler. 15. Torque converter. 16. Spool valve. A. Pressure tap, P3, for converter inlet. B. Pressure tap for pump. C. Plug (must be removed while checking primary pressure). D. Pressure tap, P1, for clutches. E. Pressure tap for lubrication relief valve.

The neutralizer signal valve (2) is activated when the left foot pedal for the brakes is pushed down. When neutralizer signal valve (2) is activated, the oil in the system goes to the reservoir (1) through valve (2). Some of the oil will go to the torque converter (15), through modulating relief valve (6).

Differential And Final Drive

Differential

DIFFERENTIAL
1. Bevel pinion. 2. Cross shaft for pinions. 3. Bevel gear. 4. Pinion (two). 5. Side gear (two).

The differential is used to send the power from the transmission to the wheels. When one wheel is turning slower than the other, the differential lets the inside wheel stop or turn slower in relation to the outside wheel.

The gear on the output shaft of the transmission turns the gear on the output shaft of the transfer gear which sends power to the drive shafts. Splines make the connection between the drive shafts and the bevel pinion (1). The bevel pinion (1) turns the bevel gear (3) which is fastened to the differential carrier. The carrier has two pinions (4), a cross shaft (2) for the pinions and two side gears (5). The connection between the two pinions (4) and the two side gears (5) is at right angles through a gear mesh. Splines make the connection between the side gears (5) and the axles.

When the machine is moving straight in a forward direction and there is the same amount of traction under each wheel, the same torque that is sent to each axle stops the pinions (4) so they cannot turn on cross shaft (2). This gives the same effect as if both wheels were on the same axle. When the force that is sent to the axles is not the same, as in a turn, forces that are not the same are put on opposite sides of the differential. This action makes the pinions (4) turn. The rotation of the pinions (4) stops or slows the inside wheel and makes the outside wheel go faster. This moves the machine through a turn under full power.

The carrier hubs for the differential run on tapered roller bearings. The pinions (4) turn on hardened steel bearings. The pinions (4) and the side gears (5) turn against thrust washers which take the end thrust against the differential carrier.

The differential gets lubrication from oil thrown about inside the housing. A flat surface on each side of cross shaft (2) lets lubricant go to the pinions (4) and to the thrust washers.

Final Drive

FINAL DRIVE
1. Axle housing. 2. Ring gear. 3. Planet gear. 4. Planet carrier. 5. Axle shaft. 6. Hub for final drive. 7. Sun gear.

The final drive is a planetary gear-type system. Ring gear (2) is fastened to the hub (6) for the final drive. Splines make the connection between the hub (6) for the final drive and the spindle. Ring gear (2) is held stationary. Planet gears (3) are held by plant carrier (4), which is fastened to the wheel assembly. Splines make the connection between sun gear (7) and axle (5). The differential turns the axle. As sun gear (7) turns, the planet gears (3) move around the inside of ring gear (2) in the same direction, but at slower speed. Planet carrier (4) turns the wheel assembly.

Nospin Differential

Operation

The differential assembly is the same on both sides of the spider. For the purpose of explanation only the parts of one side of the drive spider and in one clutch and cam unit are shown.

SPIDER AND CLUTCH
1. Clutch. 2. Spider. 3. Center cam. 4. Holdout ring. 5. Spider key. 6. Cam. 7. Retainer. A. Slot in center cam. B. Notch in holdout ring.

The clutch (1) and cam (6) are one piece with a round groove between the clutch teeth and the cam teeth.

The holdout ring (4) fits in the round groove between the teeth of the clutch (1) and cam (6), but is not connected to either the clutch or the cam. The holdout ring (4) turns freely in the groove. There is a notch (B) in the ring (4) which is engaged by the spider key (5) to control the movement of the ring in relation to the spider (2).

The drive spider (2) has clutch teeth on both sides and one long tooth (on each side) which is called the spider key (5). The center cam (3) fits inside the spider (2) and is kept in place by a snap ring. The spider key (5) turns the center cam and fits into the slot (A), turning with the spider (2). The spider key (5) pushes on either side of slot (A). The direction of movement of the spider key (5) is caused by the forward or reverse rotation of the spider (2).

A spring (8) and retainer (7) fit between the side gear and the center cam (6). The force of the spring keeps the clutch (1) and cam (6) unit engaged with the spider (2).

Clutch action (stopping power to a drive axle) happens when rotation speed of either drive axle is faster than the rotation speed of the bevel gear and shaft (2). For example: If the spider key (5) is pushing on one side of notch (B) and the speed of the holdout ring (4) [is turned through friction by the cam (6) and clutch (1)] is faster than the speed of the spider key, the holdout ring (4) will move in front of the spider key until the opposite side of notch (B) pushes the key. When this happens, friction force of the one piece clutch (1) and cam (6) causes the holdout ring (4) to move up the ramps of the center cam. Movement of the holdout ring (4) causes compression of the spring (8) and pushes the clutch and cam away from (and no longer engaged with) the spider (2).

The clutch (1) and cam (6) will move without friction on the holdout ring (4) at a faster speed than the speed of the spider (2). The turning speed of the holdout ring (4) is kept at the speed of the spider by the spider key (5). As the speed of the axle, which is not engaged, slows down to bevel gear speed, the force of the spring (8) again causes the clutch (1) and spider (2) to engage.

NOSPIN DIFFERENTIAL
1. Clutch. 2. Spider. 3. Center cam. 4. Holdout ring. 7. Retainer. 8. Spring.

Operation in Forward Turn

In a forward turn, the following action happens:

a. The clutch (7) (turning the inside wheel) is fully engaged with the drive teeth of the spider (6).

FORWARD TURNS
1. Clutch (two). 2. Holdout ring (two). 3. Center cam. 4. Cams (two). 5. Side gear. 6. Spider. 7. Clutch. 8. Side gear.

b. The speed of the opposite clutch (1) (is turned by the wheel which has the farther distance to move) must be faster than the speed of the spider to permit the turn.

c. As the speed of the outside clutch (1) starts to get faster than the speed of the spider, holdout ring (2) goes up the ramps of the center cam (3).

d. The teeth of the clutch (1) are pushed (against the force of the spring) away from the spider and into the position where it is no longer engaged.

e. As the speed of the clutch (1) gets slower than the speed of the spider, friction between the clutch (1), cam (4) and holdout ring (2) slows the ring (2) causing it to move off the ramps of the center cam.

f. The clutch (1) engages the teeth of the spider (6) again and the spider turns the clutch (1) and holdout ring (2) at the speed of the spider.

Operation in Straight Forward

When moving straight forward under power, the following action happens:

a. The teeth of the drive spider (3) engage with the teeth of the clutches (2) and power is sent to the side gears (1) which are connected to the clutches with splines.

b. Speed of the wheels will be equal, even if the traction under each wheel becomes different.

STRAIGHT FORWARD
1. Side gears (two). 2. Clutch and cam (two). 3. Spider.

When moving in straight reverse the same action will happen that happened in straight forward except: The drive spider (3) will move in the reverse direction and push on the opposite side of the clutch teeth.

When moving forward with no power (coasting), the following action happens:

a. Neither axle can turn faster than the bevel gear.

b. Both clutches are engaged with the spider.

c. Either axle can turn slower than the bevel gear as necessary when making a turn.