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| Illustration 1 | g00349161 |
Retarder Air System and Oil System (1) Transmission case (2) Differential and bevel gear case (3) Bearing cage for drive shaft (4) Line to flywheel clutch lubrication (5) Line from retarder control valve (6) Flywheel scavenge pump (7) Retarder housing (8) Engine flywheel gear case (9) Retarder hydraulic control valve (10) Transmission oil cooler (11) Line to retarder control valve (12) Hand air valve for retarder (13) Air supply from the brake system (14) Air line from retarder control lever (15) Scavenge screen (16) Line from retarder control valve to transmission lube | |
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| Illustration 2 | g00349217 |
Retarder Control Valve (9) (17) Air inlet from hand air valve (18) Valve body (19) Opening to transmission lubrication (20) Plunger (21) Opening from torque converter (22) Chamber to transmission oil cooler (23) Cover (24) Cover (25) Diaphragm (26) Valve spool (27) Spring (28) Chamber from oil cooler (29) Stop (30) Opening to retarder (31) Spring (32) opening from retarder (33) Slug | |
When hand air valve (12) is moved toward the operator, pressure air flows from valve (12) to retarder control valve (9) . The pressure air moves spool (26) to the right. The movement of spool (26) provides a path between opening (30) and opening (21) . Oil flows through opening (30) to the retarder.
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| Illustration 3 | g00349192 |
Retarder Control Valve (3) Bearing cage for the drive shaft (7) Retarder housing (8) Engine flywheel gear case (9) Retarder control valve | |
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| Illustration 4 | g00489238 |
Steering Wheel (12) Hand air valve for retarder | |
As the retarder fills, turning rotor (36) causes an increase in the oil pressure inside the retarder. The inlet oil to the retarder and the outlet oil from the retarder flow through orifices and into the spring bore in valve spool (26) . The average of the inlet oil pressure and the outlet pressure in the spring bore plus the force of the spring work against the pressure air. This occurs on the left end of valve spool (26) . When the force of the pressure oil plus the spring force become larger than the force of the pressure air valve spool (26) moves to the left. This movement causes a restriction to the flow of oil from opening (21) to opening (30) . The pressure of the oil in the retarder decreases.
A decrease in the speed of rotor (36) causes a decrease in the oil pressure inside the retarder. This causes a decrease in the oil pressure in the spring bore in valve spool (26) . This allows the pressure air on the left end of valve spool (26) to move the spool to the right. More oil flows from opening (21) to opening (30) into the retarder and the pressure inside the retarder increases.
An increase in the speed of rotor (36) will cause an increase in the oil pressure inside the retarder. This increase in oil pressure will cause valve spool (26) to move to the left.
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| Illustration 5 | g00349272 |
Transmission Oil Cooler Right Side of Engine Oil Pan (10) Transmission oil cooler | |
The valve spool is constantly moving in order to make adjustments to the retarder inlet pressure. This is done in order to compensate for the changing of rotor speeds. This constant movement of the valve spool is necessary to keep the amount of braking force in the retarder at the level set by hand air valve (13) .
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| Illustration 6 | g00349312 |
Hydraulic Retarder (34) Retarder housing (35) Stator (36) Rotor (37) Shaft (38) Gear | |
| NOTICE |
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Keep the retarder temperature in the normal operating range, which is between 120°C and 140°C (248°F and 284°F) . Keep the engine speed below high idle rpm to prevent engine damage. |
The operation of the retarder is similar to the operation of a torque converter. The teeth of gear (38) are engaged with teeth on the flywheel. Splines connect gear (38) and rotor (36) to shaft (37) . The rotor is turned by shaft (37) . Stator (35) is fastened to retarder housing (34) and the stator does not turn. The rotor turns inside the retarder housing. The rotor throws oil against the stationary vanes of the stator. This causes a resistance to the flow of oil.
The resistance to the flow of oil causes a resistance to the drive shaft. This resistance slows down the machine. As the pressure inside the retarder increases, the resistance to the drive shaft increases.
After the oil flows through the retarder, the oil flows back to retarder control valve (9) . The oil flows in opening (32) to chamber (22) . From chamber (22) , the oil flows through line (11) to transmission oil cooler (10) . From the transmission oil cooler, the oil flows through a return line back to retarder control valve (9) . The oil then flows through chamber (28) to opening (19) . The oil then flows from opening (19) through line (16) to the transmission for lubrication.
When the retarder is not being used, the oil from the torque converter divides when the oil flows in retarder control valve (9) . Some of the oil opens plunger (20) and some of the oil flows around spool (26) to the retarder. This oil is for the lubrication of the inside components of the retarder. After the oil flows through the retarder, the oil flows back to retarder control valve (9) . The oil flows through opening (32) , around the right end of valve spool (26) , and to an opening in cover (23) . The oil then flows through oil line (4) to the drive shaft bearing for lubrication. The remainder of the oil flows from opening (21) to chamber (22) through line (11) to transmission oil cooler (10) . From the transmission oil cooler, the oil flows through a return line back to retarder control valve (9) . The oil flows through chamber (28) to opening (19) . The oil then flows from opening (19) through line (16) to the transmission for lubrication.
When hand air valve (13) is moved away from the operator, pressure air to opening (17) is stopped. The lack of pressure air will cause valve spool (26) to move to the right. The pressure oil in the spring bore of spring (31) and the force of spring (31) will move the valve spool all the way to the left against cover (24) . The movement of valve spool (26) closes inlet opening (21) to opening (30) . Inlet oil to the retarder is stopped. Rotor (36) pushes the oil out of the retarder to control valve (9) . The oil flows through opening (32) around valve spool (26) to an opening in cover (23) . The oil then flows through an oil line to the reservoir in the differential and bevel gear case.
The position of hand air valve (9) controls the amount of pressure air to retarder control valve (9) . This controls the pressure of the oil inside the retarder. An increase in pressure air to retarder control valve (9) causes a higher pressure of the oil inside the retarder. This causes an increase in the braking force of the retarder.