Usage:
793B (1HL),
793C (4AR) Off-Highway Trucks
This modification will install an on/off solenoid in the hoist system of the 793 Off-Highway Truck to allow the truck body to lower while the body is still loaded. The hydraulics and electrical circuits need to be modified. A mounting plate must be fabricated and parts ordered from the parts list before starting the assembly process.
The modification procedure is as follows:
Fabrication:
Fabricate the valve mounting plate using Illustration 1 and the dimensions in Chart 1.
Illustration 1.
This is a view of the fabricated plate.
Hydraulics:
Illustration 2.
This is a view of 8C-6162 Manifold (2).
1. Install one 149-2610 Solenoid Valve Group (1) into the 8C-6162 Manifold (2) port (A).
2. Install one 6V-8637 Adapter (9) and one 3D-2824 Seal (7) into 8C-6162 Manifold (2) port (C).
3. Install one 6V-9007 Elbow (8) and one 3D-2824 Seal (7) into 8C-6162 Manifold (2) port (B).
4. Install the 8C-6162 Manifold (2) to the Plate (fabricated) (17) with two 6V-7981 Bolts (13), two 8T-4133 Nuts (12), and two 7X-7729 Washers (14).
Illustration 4.
5. Remove the existing hose from the head end port (D) on the left side of the hoist valve.
6. Install one 6V-9007 Elbow (8) and one 3D-2824 Seal (7) into the 126-3765 Adapter (3). Orient the elbow so the elbow points to the rear of the truck.
7. Install the 126-3765 Adapter (3) to the hoist valve with a 4J-0522 Seal (10). Reinstall the existing hose to the head end port (D) with four 8T-4176 Bolts (11) and the existing split flanges. Note: The 6V-9007 Elbow should be on top of the adapter.
8. Remove the brake cooling port plug from the top of the hoist valve (E). Note: the cooling port is at the rear of the hoist valve on the tank side.
9. Install one 6V-9007 Elbow (8) and one 3D-2824 Seal (7) into the brake cooling port (E). Orient the 6V-9007 Elbow (8) so that the elbow points to the rear of the truck.
Illustration 5.
10. Remove the existing bolts holding the brake cooling line clip and the grease line clip (F) from the bosses on the cross tube. The cross tube is directly behind the hoist valve.
11. Install the Plate (fabricated) (17) and the existing clips to the existing bosses using one 8T-4195 Bolt (15), one 8T-4136 Bolt (11), and two 7X-7792 Washers (14).
Illustration 6.
12. Install one 102-1234 Hose (4) and two 6V-9746 Seals (6) between the 6V-9007 Elbow (8) on 126-3765 Adapter (3) and the 6V-9007 Elbow (8) on the 8C-6162 Manifold (2).
13. Install one 9C-2418 Hose (5) and two 6V-9746 Seals (6) between the 6V-8637 Adapter (9) on the 8C-6162 Manifold (2) and the 6V-9007 Elbow (8) in port (E) on top of the hoist valve. Note: The 90° coupling on the hose goes towards the manifold.
Electrical:
NOTE: Turn off battery disconnect before performing this procedure.
1. Move wire #217 (black) from pin 17 to pin 18 on the EPTC-II connector.
2. If the truck is equipped with the "Oil Renewal System", use the existing 117-9364 Control Group (18) and go to Step 10.
3. Install a 117-9364 Control Group (18) in the back of the cab and mount securely.
4. Fabricate a harness with sufficient length to connect the 117-9364 Control Group (18) to the fuse panel. On one end of the harness, form a "T" connection using two 100 mm (4.0 in) pieces of wire.
5. Attach an 8T-9850 Terminal (24) and a 6T-6505 Housing (25) to one of the "T" ends. Attach a 4S-1988 Terminal (26) to the other "T" end. Attach an 8T-8730 Socket (22) to the long end of the harness and insert it into "Location 1" of a 102-8810 Plug Kit (21).
6. Remove the 160-PU Wire from the hoist fuse and connect it to a 4S-1988 Terminal (26).
7. Attach the 8T-4850 Terminal (24) to the hoist control fuse.
8. Fabricate a length of wire with an 8T-8730 Socket (22) on an end and a 2L-8079 Connector (27) on the other with a sufficient length to reach from the 117-9364 Control Group (18) to the cab ground lug. Insert the 8T-8730 Socket (22) into "Location 2" of the 102-8810 Plug Kit (21). Connect the 2L-8079 Terminal to the cab ground lug.
9. Insert a 9G-3695 Plug (23) into "Location 3" and "Location 5" of the 102-8810 Plug Kit (21).
10. Fabricate a length of wire with a 9X-6857 Socket (19) on one end and an 8T-8730 Socket (22) on the other with sufficient length to reach from the EPTC-II Control to 117-9364 Control Group (18). Insert the 9X-6857 Socket (19) into "Location 34" of the EPTC-II Control. Insert the 9X-6857 Socket into "Location 4" on the 117-9364 Control Group (18).
11. Fabricate a harness with two wires of sufficient length to reach from the 117-9364 Control Group (18) to the snub solenoid.
12. On one end, of the harness, attach two 8T-8730 Sockets (22) and insert them into a 102-8807 Plug Kit (20) and connect to the 149-2610 Valve Group.
13. Attach an 8T-8730 Socket (22) to the opposite end at the wire inserted in pin 1 of the 149-2610 Valve Group (1). Insert the 8T-8730 Socket (22) into "Location 6" of the 117-9364 Control Group (18).
14. Attach a 2L-8079 Connector (27) to the opposite end of the wire inserted in pin 2 of the 149-2610 Valve Group (1). Connect the 2L-8079 Terminal (22) under the cab ground terminal.
Illustration 7.
Modification wiring diagram. Dashed lines indicate that wiring is necessary when truck is NOT equipped with "Oil Renewal System"
Adaptable To: 793B (1HL1-Up), 793C (4AR1-Up)
Effective With: 793C (4GZ1-Up)