F369977-1 Force INTERLOCK ARM

Introduction
This Special Instruction will describe the cause of oil transfer between the tank for the steering system and the tank for the hoist system. This Special Instruction will also provide instructions for removing components that will permanently prevent the transfer of oil by removing the feature that allows the body to be lowered when the engine is stopped.If you apply this Special Instruction, you will leave the machine without this feature that allows the body to be lowered when the engine is stopped. The feature should be reinstated by using the procedure in Service Magazine, SEPD0703 6 October, "New Procedure for Lowering the Body With the Engine Stopped. Parts Can Be Field Installed".Description of the Problem
In certain operating conditions, there can be a transfer of oil between the tank assembly for the steering system and the tank assembly for the hoist system.This can occur after dumping when the machine is backed up on a grade. If the grade is steep enough and the body does not go over center then the body can move forward slightly at the end of the dump cycle. This movement causes a vacuum in the line that connects the hoist valve to the 179-9223 Check Valve . If this happens the check valve will unseat and oil will be drawn from the steering system hydraulic tank through the 145-8587 Lowering Control Valve . The 145-8587 Lowering Control Valve provides a permanent connection between the tank for the steering system and the 179-9223 Check Valve . This permanent connection is always closed unless the 145-8587 Lowering Control Valve is operated manually. The 145-8587 Lowering Control Valve would only be operated manually if it was necessary to lower the body with an engine that was stopped. The vacuum does not last long, but the transfer of oil can be significant over many cycles of the hoist. The oil level in the tank for the steering system will fall, while the oil level in the tank for the hoist system will rise.The transfer of oil can be stopped by removing the connection between the hoist valve and the check valve. Refer to Service Magazine, SEPD0703 6 October, "Preventing Oil Transfer Between the Tanks for the Steering and Hoist Systems" for a quick fix to the problem.Removal of the Feature for Lowering the Body
You can remove all of the components that are associated with the lowering of the body when the engine is stopped. Machines with the serial numbers AWR272-UP and AXM492-UP do not have these components. These later machines have a different arrangement for lowering the body when the engine cannot be run. If you decide to remove these components you should install the alternative arrangement that is described in the service magazine article that is referenced in the introduction.Table 1 contains a list of parts that must be removed from the machine.Table 2 contains a list of new parts that are required.
Table 1
Parts That are No Longer Required    
Item    Quantity    Part Number    Description    
1     1     3J-1907     O-Ring Seal    
2     1     3U-2753     Clip    
3     2     5P-7462     Clip    
4     2     5P-7463     Clip    
5     1     5P-9297     Clip    
6     3     6U-0455     Strap    
7     2     6V-0683     Grommet    
8     1     7S-8920     Clip    
9     1     7S-8921     Clip    
10     1     7U-7310     Shuttle Valve    
11     2     8T-4121     Hard Washer    
12     1     8T-4133     Nut    
13     1     8T-4137     Bolt    
14     2     8T-4223     Hard Washer    
15     1     8T-4244     Nut    
16     1     8T-4956     Bolt    
17     1     122-8291     Hose    
18     1     145-8587     Lowering Control Valve    
19     2     148-8336     Connector    
20     1     148-8374     Elbow    
21     2     148-8378     Elbow    
22     1     150-4027     Tee    
23     1     150-4050     Elbow    
24     1     153-6248     Adapter    
25     1     165-7948     Check Valve    
26     1     194-6925     Tube    
27     1     201-0959     Hose    
Table 2
Required Parts    
Item    Quantity    Part Number    Description    
28     1     221-2821     Manifold    
29     1     9S-4191     Plug    
30     1     3J-1907     O-Ring Seal    
31     1     148-8407     Plug    
32     1     9S-4185     Plug    
33     1     3K-0360     O-Ring Seal    735 Removal Instructions
Refer to Illustrations 1 to 4. Remove all of the parts that are identified in the illustrations and in Table 1. Refer to illustrations 5 and 6. Install all of the parts that are identified in the illustrations and in Table 2.