Usage:
D250E (5TN),
D300E (7FN),
D350E (9LR),
D400E (2YR) Articulated Trucks
- SUPPLEMENT: NOVEMBER 10, 1997
Service Magazine; September 22, 1997; Page 29;"Hydraulic Control System Improvements Reduce Retarder Response Time"; for D250E (5TN), D300E (7FN), D350E (9LR), D400E (2YR) Articulated Trucks.
Chart 3, item 10 is incorrect. A 6V-9849 Elbow is required instead of the specified 6V-9850 Elbow.
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Description of Change: A retarder with improved response time is now used on articulated trucks. A new valve group, accumulator, and hose reduce retarder response time.
Adaptable To: The new 144-4279 Valve Group with 147-7311 Accumulator and 092-7763 Hose Assembly (on D250E & D300E) and 114-6652 Hose Assembly (on D350E & D400E) is a direct replacement for the former 118-9599 Valve Group. The improvements are effective with D250E (5TN1256), D300E (7FN603), D350E (9LR383), D400E (2YR637) Articulated Trucks, and are adaptable to earlier machines. To adapt earlier machines, use the following procedures.
NOTE: When removing the existing retarder valve from the machine, save the fittings for re-use on the new valve.
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To prevent personal injury, move the control levers backward and forward to release the pressure in the hydraulic system. Slowly loosen the cap of the hydraulic tank to release any pressure in the tank. Be cautious of hot hydraulic oil when any lines are disconnected in the hydraulic system.
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Sub-assemble the new valve, hose, elbow, and accumulator to ready for installation on the machine. See Illustrations 1, and 2 for the valve and accumulator sub-assembly.
Illustration 1. Valve, accumulator, elbow, and hose assembled before assembly to the D250E or D300E Articulated Truck.
Illustration 2. Valve, accumulator, tee, and hose assembled before assembly to the D350E or D400E Articulated Truck.
The new hose (6) replaces the previous supply hose from the transmission (on the D250E & D300E) or the torque converter lock-up clutch control valve (on the D350E & D400E) and is connected to port P2 on the new valve (see Illustrations 1 & 2). The accumulator is assembled to the port the supply hose was attached to on the former valve (Port marked "A" or "P1" on new valve).
NOTE: Before mounting the assembly to the truck, pre-charge the 147-7311 Accumulator to 1447 kPa (210 psi).
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If the accumulator needs to be charged, dry nitrogen is the only gas approved for use in the accumulators. The charging of oxygen gas in these components by accident will cause an explosion. This danger can be avoided by the use of nitrogen cylinders with standard CGA (Compressed Gas Association Inc.) No. 580 connections. Do not go by color codes or other methods of identification to tell the difference between nitrogen and oxygen cylinders. In any application, never use an adapter to connect your nitrogen charging group to a valve outlet used on both nitrogen, oxygen or other gas cylinders. Be sure you use dry nitrogen.
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Assemble the new valve, accumulator, and hose assembly to the truck. The drain hose to the transmission is attached to the same port on the new valve as it was on the former valve (T1 on D250E & D300E Articulated Trucks and T2 on D350E & D400E Articulated Trucks). The return hose from the inter-axle differential lock solenoid valve is connected to port T1 on the D350E & D400E Articulated Trucks.
The tee fitting installed in port C3 of the new valve replaces the fittings installed in ports C1 & C2 of the former valve. These ports (C1 & C2) remain plugged on the new valve.
The pressure switch removed from the side of the former valve is fitted to the tee fitted in port C3 of the new valve, Item 5 in Illustrations 1, and 3 and Item 7 in Illustrations 2, and 4.
On D350E & D400E Articulated Trucks, the supply hose for the inter-axle differential solenoid valve is connected to one side of the tee which is installed in port P2 on the rear face of the valve. The supply hose from the lock-up clutch control valve is connected to the other side of the same tee.
On D250E & D300E machines, a pressure tap can be added. Use the parts listed to tee into the hose side of the tee off the front of the valve as it is positioned on the truck.
Use the pressure tap to check and ensure the correct pressures with the retarder control lever in the off position and in all three operating positions while the engine is at low idle and normal operating temperature. The correct pressures are listed in the following chart.
Illustration 3. D250E & D300E. Top view under right hand side of cab. Arrow depicts pressure tap fitting location.
Illustration 4. D350E & D400E. View from rear of engine and torque converter looking forward.