Usage:
Introduction
NOTE: For Specifications with illustrations, make reference to STEERING AND BRAKE SYSTEM SPECIFICATIONS FOR 910 WHEEL LOADER, Form No. REG01255. If the Specifications in Form REG01255 are not the same as in the Systems Operation and the Testing and Adjusting, look at the printing date on the back cover of each book. Use the Specifications given in the book with the latest date.
Steering System
STEERING SYSTEM SCHEMATIC
1. Steering cylinder on left side. 2. Steering cylinder on right side. 3. Supply tank for the power master cylinder for the wheel brakes. 4. Steering control assembly. 5. Flow control and relief valve. 6. Power and master cylinder for the wheel brakes. 7. Pump section for loader hydraulic system. 8. Oil line to loader control valve sections. 9. Pump section for the steering and brakes hydraulic systems. 10. Oil line from supply tank. 11. Oil line to supply tank.
The hydraulic system has one supply tank which holds oil for both the steering system and the loader system. The hydraulic pump is a gear-type and has two sections. The location of the pump is on the side of the engine on the right side of the machine. The pump is driven by the timing gears for the engine.
The section at the shaft end is the pump (7) for the loader hydraulic system. The other section is the pump (9) for the steering system and power brake.
The oil from pump (9) goes into flow control and relief valve (5). There are three outlets from valve (5). The oil from one outlet goes to the steering control assembly (4). This oil flow is limited, by valve (5), to 11 U.S. gpm (41.6 lit/min). The oil goes through one of the other two outlets to the oil supply tank when the pump output is more than 11 U.S. gpm (41.6 lit/min). The oil goes out the third outlet only when oil pressure is more than approximately 2500 psi (175.7 kg/cm2).
HYDRAULIC PUMP
7. Pump section for loader hydraulic system. 8. Oil line to loader control valve sections. 9. Pump section for steering and brake hydraulic systems. 10. Oil line from supply tank.
When the steering wheel is not being turned, the oil goes through the steering control assembly (4) and goes to the power cylinder of the brake master cylinder (6). When the brakes are not activated, the oil goes through the power cylinder and goes to the supply tank through oil line (11).
The wheel brakes have a hydraulic system that is not connected to the steering hydraulic system. Tank (3) is a supply tank of hydraulic brake fluid for the master cylinder (6) and for the lines and brake cylinders of the wheel brakes.
Flow Control And Relief Valve
OIL LINES UNDER FLOOR PLATES
1. Flow control valve. 2. Oil line to supply tank. 3. Oil line to steering control assembly. 4. Outlet line from relief valve. 5. Oil line from the hydraulic pump. 6. Power and master cylinder for the wheel brakes.
The flow control valve (1) is under the floor plates. The oil from the steering pump goes through line (5) into control valve (1). When the engine speed is slow, the pump output (gpm, lit/min) is low and the oil goes through the control valve and through line (3) to the steering control assembly. The holes in valve (10) let only 11 U.S. gpm (41.6 lit/min) go through the valve into line (3). When the engine is running at high speed, the output of the pump is approximately 20 U.S. gpm (75.7 lit/min). Any output higher than 11 U.S. gpm (41.6 lit/min) moves valve (10) and goes to the tank through line (2).
The pressure setting of relief valve (8) is about 2500 psi (175.7 kg/cm2). If the pressure of the oil from the pump to the steering cylinders goes to this setting, the oil opens the relief valve and goes through fitting (7) and then through line (4) to the tank.
The setting of the relief valve can be changed. The thickness of shims (9) over the spring in relief valve (8) are for the adjustment. Add shims for an increase or remove shims for a decrease in the pressure setting of the relief valve.
FLOW CONTROL VALVE
2. Oil line to supply tank. 3. Oil line to steering control assembly. 5. Oil line from hydraulic pump. 7. Fitting for the tube to the tank. 8. Relief valve. 9. Shims. 10. Valve.
Steering Control Assembly
The pump oil to the inlet (3) of the steering control assembly comes from the flow control and relief valve. The oil goes through the control assembly and keeps it filled with oil. When the steering wheel is turned, the steering wheel shaft turns pin (7) in drive (4) which turns star gear (5) in ring gear (6).
STEERING CONTROL ASSEMBLY (CROSS SECTION)
1. Outlet to power brake chamber. 2. Ball check valve. 3. Inlet from the hydraulic pump. 4. Drive for gear. 5. Pump star gear. 6. Ring gear of the pump. 7. Pin for drive.
The pump star gear (5) when it is turned and the hydraulic pump, moves the oil in the steering control assembly to the steering cylinders. The direction the steering wheel is turned, either to the right or to the left, controls where the flow goes. The oil goes to the rod end of the right and the head end of the left steering cylinders for a right turn or, to the rod end of the left and the head end of the right steering cylinders for a left turn. The faster the steering wheel is turned, the larger amount of oil (gpm or lit/min) goes to the steering cylinders and, the faster the turn.
CORRECT LOCATION OF PIN IN DRIVE FOR GEAR
4. Drive for gear. 5. Pump star gear. 6. Ring gear of the pump. 7. Pin for drive.
NOTE: A moving machine can be turned to get it off the road when the engine is not running (no oil from the hydraulic pump for steering). When the machine and engine are both stopped, it is too difficult to move the steering wheel to turn the machine.
RIGHT SIDE STEERING CYLINDER
8. Steering cylinder. 9. Rod (extended from cylinder on right side for a left turn).
Brake System
Parking Brake
The location of the parking brake is in the end of the machine with the engine and transmission. The brake is on the drive shaft (2) to the front wheels of the machine. It is a mechanical brake with a brake drum (4) and two lined inner shoes.
When the operator moves the brake control lever, to put on the parking brake, the cable (1) connection to the brake control moves the lever (3). The lever pushes the inner shoes against the inner surface of the brake drum (4) and keeps the drive shaft from turning.
PARKING BRAKE
1. Cable connection to brake control. 2. Drive shaft. 3. Lever. 4. Brake drum.
HYDRAULIC POWER BRAKE SCHEMATIC
1. Oil supply tank. 2. Steering control assembly. 3. Supply tank for the master cylinder. 4. Oil line from power brake to supply tank. 5. Oil line from steering control assembly to power brake. 6. Oil line from flow control valve to steering control assembly. 7. Brake calipers on front wheels. 8. Power and master cylinder for the wheel brakes. 9. Left pedal for wheel brakes. 10. Oil line from flow control valve. 11. Oil line from pump to flow control valve. 12. Oil line from relief valve to power brake. 13. Flow control valve and relief valve. 14. Right pedal for wheel brakes. 15. Neutralizer valve for transmission. 16. Pump section for loader system. 17. Pump section for steering system. 18. Oil line to loader control valves. 19. Oil line from oil supply tank to pump.
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Always install the safety bar, to keep the machine straight, before doing any work under the machine. With the parking brake on, the drive shaft does not turn but the differential gears, in the drive to the front wheels, can let the wheels turn in opposite directions which will turn the machine. |
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The hydraulic pump oil for the steering system also operates the power brakes (when the engine is running) when either left pedal (9) or right pedal (14) is pushed for wheel brake application.
The oil from the steering pump section (17) goes to flow control and relief valve (13). This valve lets only 11 U.S. gpm (41.6 lit/min) of the pump oil go to the steering control assembly (2). The hydraulic pump oil from the steering control assembly goes to the power cylinder part of the power and master cylinder (8).
OIL LINES WITH FLOOR PLATES REMOVED
5. Oil line from steering control assembly to power brake. 6. Oil line from flow control valve to steering control assembly. 8. Power and master cylinder for the wheel brakes. 10. Oil line from flow control valve to supply tank. 11. Oil line from pump to flow control valve. 12. Oil line from relief valve to power brake. 13. Flow control valve and relief valve.
When a brake pedal is pushed, the pressure of the pump oil in the power cylinder increases to approximately 300 psi (21.1 kg/cm2). This pushes the power cylinder piston and the master cylinder piston. The master cylinder piston increases the pressure of the hydraulic fluid to the brake calipers (7) for brake application on the wheels.
The master cylinder, brake caliper (7) and the lines between them is a separate hydraulic system. The supply tank (3) is the reservoir for this system. The supply tank keeps the master cylinder full of hydraulic brake fluid. The brake pedal, when pushed, and the power cylinder can increase the pressure to the pistons in the brake calipers to more than 1400 psi (98.4 kg/cm2).
The left brake pedal (9) has a connection to the transmission neutralizer valve (15). The neutralizer valve is part of the transmission oil system. The neutralizer valve is in a pressure oil circuit to a clutch in the transmission. The normally closed neutralizer valve is opened when the left brake pedal (9) is pushed to stop the machine. The open valve lets the oil in the circuit to the clutch run into the oil sump in the transmission and the clutch is released. With the clutch released the torque converter keeps turning when the brakes stop the wheels.
The right brake pedal (14) does not have a connection to the transmission neutralizer valve.
TRANSMISSION NEUTRALIZER VALVE (Floor Plate Removed)
9. Left pedal for wheel brakes. 15. Neutralizer valve for transmission.
Power And Master Cylinder For The Wheel Brakes
The brake hydraulic system of the master cylinder and brakes for the wheels is separate and has no connection with the hydraulic system of the power cylinder. The power cylinder for the brakes gets pump oil that has gone through the steering control assembly when the engine is running.
The flow of oil goes through inlet (11) into chamber (A). When the brakes are not in use, the oil in chamber (A) goes through passage (10), in valve (2), into chamber (C). The oil in chamber (C) goes through outlet (12) and then to the supply tank.
CROSS SECTION OF POWER CYLINDER AND MASTER CYLINDER
1. Push rod. 2. Valve. 3. Power piston. 4. Relief valve. 5. Spring. 6. Connector. 7. Piston. 8. Spring chamber. 9. End Cap. 10. Passage. 11. Inlet. 12. Outlet. 13. Reaction Piston. 14. Outlet to the brakes. A. Chamber. B. Location of power piston with brake pedal pushed (when the engine is running). C. Chamber.
The linkage from the brake pedals is connected to push rod (1). When a brake pedal is pushed for brake application, the brake linkage moves pushrod (1) and valve (2). The movement of valve (2) into connector (6) closes passage (10). With passage (10) closed, the pump oil in chamber (A) moves power piston (3) against connector (6). The combination of the pump oil force on power piston (3) and the force on the brake pedal on valve (2) moves connector (6) against piston (7) in the master cylinder. When piston (7) is moved the brake fluid in spring chamber (8) is pushed through outlet (14) to the brakes which either stop or make a decrease in the speed at the wheels.
The operator can feel the application of the brakes because the pedal, pedal linkage, push rod (1) and valve 92) are mechanically connected and valve (2) is against both connector (6) and reaction piston (13). The operation of reaction piston (13) lets a small amount of the brake fluid in spring (8) chamber push on the end of the reaction piston when the brake pedal is pushed.
The pressure of the pump oil in chamber (A) gets an increase when passage (10) in valve (2) is closed. Relief valve (4) opens when the oil pressure is 290 psi (20.4 kg/cm2).
The maximum oil pressure on piston (3) pushes connector (6) against piston (7) and the pressure of the brake fluid moved by piston (7) to the brakes can be 1400 psi (98.4 kg/cm2).
When the engine is stopped or if there is no pump oil to the power cylinder the brakes can operate. More force is needed on the brake pedal to move the pedal linkage, pushrod (1), valve (2), connector (6) and piston (7) to push the brake fluid in spring chamber (8) through outlet (14) to the brakes.
Wheel Brakes
The brakes on the wheels are disc-type. The disc (5) is bolted to the wheel and turns with the wheel. The caliper (1) is bolted to the housing for the axle and is held stationary.
A TWO WHEEL BRAKE (RIGHT WHEEL)
1. Caliper, on axle housing. 2. Pin (four), to hold carrier and lining assemblies. 3. Oil lines to pistons on other side of caliper. 4. Brake fluid inlet for the pistons in the caliper. 5. Disc, on the wheel. 6. Screw valve (two), to let air out of the brake fluid when necessary. 7. Bolts (four), to fasten the position of pins (2).
The disc turns in the caliper when the wheel turns. Part of the disc is always in the caliper. Each caliper has two carrier and lining assemblies (9) with pistons (8) that are activated by brake fluid pressure when a brake pedal is pushed. The pistons push the carrier and lining assemblies against both sides of the disc either to stop or to slow the turning disc and wheel.
CALIPER PARTS
1. Caliper. 2. Pin (four). 3. Oil line. 4. Inlet in cap over piston. 6. Screw valves. 7. Bolts (four). 8. Pistons (four). 9. Carrier and lining assembly (two).
The machine has brakes on each front wheel. An optional brake system has brakes on the four wheels.
Each caliper for the two wheel brake has two large carrier and lining assemblies and four pistons. The two wheel brakes have a total of four carrier and lining assemblies and eight pistons.
Each caliper for the four wheel brake has two small carrier and lining assemblies and two pistons.
The four wheel brakes also have a total of eight carrier and lining assemblies and eight pistons.
The eight pistons for the two wheel brakes and for the four wheel brakes are the same size. The area of contact for the four large carrier and lining assemblies on the two wheel brakes is the same as the area of contact for the eight small carrier and lining assemblies on the four wheel brakes.
A FOUR WHEEL BRAKE
1. Caliper, on axle housing. 2. Pin (four), to hold carrier and lining assemblies. 3. Oil line for brake fluid to piston on other side of caliper. 4. Brake fluid inlet for the pistons in the calipers. 5. Disc, on the wheel. 6. Screw valve (two). 7. Bolts (four) to fasten the position of the pins (2).