Usage:
D25C, D30C, D35C, D350C Trucks So Equipped
Description of Change: A new TCMR control arrangement is used on the above articulated dump trucks. The revised air control air lines will cause the retarder indicator to operate differently.
The torque converter must be locked up before the retarder can operate. The retarder control arrangement ensures that the converter stays locked up as long as the engine speed is above 850 rpm when the retarder control is in the "ON" position.
With the former arrangement (see Illustration 1), the pressure switch which causes the dash mounted "Retarder ON" indicator to light up, is positioned in the circuit so it will cause the indicator to go on only when the retarder is actually engaged. With this arrangement, if the engine is started with the retarder control in the "ON" position, the torque converter will immediately lock up and the engine can stall. But the operator will not see the "Retarder ON" indicator light up because the engine speed is less than 850 rpm.
Illustration 1. Former TCMR control arrangement.
With the new arrangement, the pressure switch, which causes the dash mounted "Retarder ON" indicator to light up, is positioned in the circuit so it will cause the indicator to go on anytime the retarder control is in the "ON" position, regardless of engine rpm. With this arrangement, the operator has a visual indication that the retarder control in the "ON" position as soon as the engine is started.
Adaptable To: The new TCMR control arrangement is in effect with D25C Truck 9YC678, D30C Truck 7ZC205, D35C Truck 2GD100, and D350C Truck 8XC280. The new arrangement is adaptable to all earlier trucks. The parts required to install the new arrangement on former trucks are listed in the chart.
Use the Installation Procedure that follows to convert trucks with the former TCMR control arrangement to the new arrangement.
Illustration 2. New TCMR control arrangement.
Installation Procedure
1. Park the truck on a level surface and apply the parking brake.
2. Drain the air from the air system.
3. Remove and discard the 6U6552, 5U3951, 7U1290, and 6U5415 Hose Assemblies and the 6K1972 Elbow. See Illustration 1.
4. Remove and keep the 5U3616 Hose Assembly and the 520572 Tee. See Illustration 2.
5. Remove the 7U1271 Air Pilot Valve with the 7U1269 Bracket from the front of the transmission. Remove the valve from the bracket. Keep the valve and mounting hardware and discard the bracket.
6. Install the 7U1271 Air Pilot Valve on the new 7U2653 Brackets with the existing hardware. Install the new bracket on the front right hand side of the transmission, as shown in Illustration 2, with three of the existing transmission cover mounting bolts.
7. Install the 4S6399 Adapter and the 6U5637, 6U0910, 5U3611, and 5U9009 Hose Assemblies as shown in Illustration 2.