Turn tubing nut slowly with wrench while turning tubing with other hand. When the sleeve grips the
tubing, that is when the tubing can no longer be turned by hand, stop turning nut and note position of
wrench. This is termed the ring grip point.
Then, tighten the nut an additional one turn past the ring grip point.
Unscrew nut and remove the tubing from the mating fitting, or presetting tool. Inspect the preset as
described in Figure 6-1.
When installing a preset tubing assembly, lubricate with clean oil.
At installation of tubing assemblies, do not overtighten tubing nuts.
Insert tubing assembly into fitting and tighten nut until a sharp rise in torque Is felt. Starting at position of
sharp torque rise, tighten the nut 1/4 additional turn to complete the assembly.
At the point where the torque starts to rise, the sleeve and tubing are just touching the seat. An additional 1/4 turn
produces a seal with the fitting and restores the bow to the sleeve.
Replace damaged or defective fittings.
DISASSEMBLY OF MAJOR COMPONENTS:
Limit disassembly of major components to the extent necessary
to repair or replace a given assembly. All major components are covered In the following paragraphs. Refer to Figure 7-1
for major components.
Unless otherwise specified, all figures referenced in this section will be found In Section VII, Illustrated Parts
Remove tubing and hose assembly as needed in the disassembly process. Tag tube or hose assembly for
Do not attempt to disassemble any part of the brake air system without first being sure that all pressure has
been relieved from the system. (See Figure 7-1 and 7-2).
AIR OVER HYDRAULIC BRAKE SYSTEM ( TUBING GROUP ): See Figure 7-2. The following paragraphs
contain disassembly, cleaning, inspection, repair or replacement and assembly instructions for the air over hydraulic brake
Disassembly- Disassemble the air over hydraulic brake system only to the extent necessary - to repair or replace a
defective part or parts.
Unscrew and remove the service air hose assembly (1, Figure 7-2) at the towbar mounting post. Do not
disassemble the service air hose assembly unless necessary.
Unscrew tube assy. (8, Figure 7-2) at the towbar mounting post. Disengage from connector (7) Remove
adaptor (2). Unscrew and remove bulkhead coupling (3) from