Spicer Tandem Drive Axle Dual Range & Double Planetary 34,000-45,000 lbs - Manual (Page 62)

Axle Range Selection and Inter-Axle Differential Lockout System
(with Axle Range Interlock and Straight-air type Lockout)
Air pressure with axle in High Range,
Inter-Axle Differential Engaged, and
Axle Shifter Valve Lever Blocked.
Pressure switch and speedometer adapter
required for vehicles with transmission
drive speedometers.
Solenoid valve required for vehicles
not equipped with automatic safety brakes.
Description and Operation
The Axle Range Interlock feature in this system is designed to prevent
axle shifting when the inter-axle differential is locked out (or when
lockout is engaged).
The basic shift system operates the same as the standard shift system to
shift axle and engage or disengage lockout. However, it varies by adding
an Interlock Pin Assembly to the axle range shifter valve and an Interlock
Control Valve to the lockout cylinder. These two components are inter-
connected with air lines (see illustration above). In operation, the Interlock
Pin Assembly blocks movement of the axle range shifter valve lever when
air pressure is present. Refer to the following page for operation
description.
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