Spicer TPCS (Tire Pressure Control System) Service Manual - Manual (Page 18)

18
Pneumatic Service
Wet Tank Requirements
A minimum wet tank volume is required for proper
operation of the Tire Pressure Control System. Verify
that the vehicle is equipped with the proper Wet Tank:
• 1400 in 3 (6 gal.) for tractor only or tractor/
trailer configuration
• 2800 in 3 (12 gal.) for a tractor with a two
trailer configuration. See Figure 9 for proper
hose selection. Do not reduce the size of wet
tank or hoses.
Supplied Parts and Fittings
In selecting parts, be alert to slight differences between
items and make sure you are using the correct part. In
particular, watch out for different hose and tubing
lengths and fitting diameters.
No Kinking or Stretching
All hose and tubing segments should assemble with
slight excess lengths. There should be no kinks or
sharp bends and no segments should require stretching
in order to tighten joints. When servicing hoses be sure
not to increase or reduce overall control volumes. If
any tube or hose segment does not fit easily, it could
mean you are not using the proper part or that you are
not following service procedures properly.
Joint Compound
Here are some important “DO’s” and “DON’Ts” regard-
ing the use of thread sealant:
• Do apply a thin coating of compound on male
threads of pipe joints.
• Don’t use any compound on O-ring, compres-
sion, or flare fitting connections. Instead, apply
a thin coat of silicone grease to O-rings and
flares.
• Don’t use Teflon thread tape anywhere in the air
system. (Teflon tape shreds can become lodged
in valving.)
! Caution: The Spicer Tire Pressure Control
System has the ability to maximize the vehicle’s
ability to operate in various conditions. Until the
system adjusts to repairs, tire pressures may be
temporally lower than expected. The above
procedure is necessary before returning the
vehicle to service.
Note: Figure 8 shows the pneumatic layout for a three-
axle installation of the Tire Pressure Control System.
This layout is typical for a tractor or straight truck and
shows the air line for a trailer connection. Refer to this
figure when performing any of the following proce-
dures.
Note: See the Troubleshooting Manual AXTS-0010 for
procedures on locating pneumatic problems with the
Tire Pressure Control System.
Note: See Section 3 on Electrical Service for informa-
tion on electrical connections to the Pneumatic Control
Unit.
Service Guidelines
The Tire Pressure Control System does not require
additional maintenance. However, additional care with
the vehicle’s air system may assure trouble free opera-
tion. The following are some general rules that apply to
Tire Pressure Control System service:
Clean and Dry Air Supply
The Spicer Tire Pressure Control System requires a
constant supply of clean dry air. An adequately sized and
properly maintained air dryer is critical for continued
proper operation of the Tire Pressure Control System.
Even though the air dryer may be working properly,
moisture can accumulate in the wet tank during normal
operation due to the increase in air consumption. It is
important to drain the wet tank daily. Draining the wet
tank completely (to 0 pressure) when the truck is not in
use will help keep moisture under control.