Chevrolet Light Duty Truck 1973, Service Manual

Page: 772 / 979

9 -6 STEERING
STEERING COLUMNS C AND K
SERIES
The function locking energy absorbing steering column
on C and K Series Trucks which, in addition to steering
the vehicle, includes three important functions:
1. The column is energy absorbing, designed to
compress up to 8.25 inches in a front-end collision
to minimize the possibility of injury in the event of
an accident.
2. The ignition switch and lock are mounted
conveniently on the column.
3. With the automatic transmission column, the
ignition, steering and gearshifting operation can be
locked to inhibit theft of the vehicle.
The function locking energy absorbing steering column
assembly is used on all C and K series trucks. This
column is designed to compress under impact. When an
vehicle is being driven, the forward movement of the
vehicle and the forward movement of the driver both
constitute a form of energy or force (Fig. 8). If a vehicle
is involved in a frontal collision, the primary force
(forward movement of the vehicle) is suddenly halted,
while the secondary force (the driver) continues in the
pre-collision direction. A frontal collision generally
involves these two factors - the primary and the
secondary forces. The secondary impact occurs if the
driver is thrust forward onto the steering wheel and
column.
The function locking energy absorbing column is
designed to absorb these primary and secondary forces
to the extent that the severity of the secondary impact is
reduced. In reacting to the primary force the steering
column compresses (Fig. 9), thereby reducing its
tendency to move rearward. A split second later, if the
driver is thrown forward and strikes the steering wheel
(the secondary impact), his energy is also partially
absorbed by compression characteristics of the column.
The operation of the column mounted lock (Fig. 10) is
described as follows:
To start the vehicle, you insert the key in the lock, turn
the unit to “start” and let the switch return to the “on”
position. The “off”, and “accessory” positions are also
the same as in previous years, and are located in exactly
the same order as they were when the unit was mounted
on the instrument panel. The only thing that has
changed is the lock’s position and its function. By
mounting the ignition lock on the column, two new
features are possible.
When you engage the shift lever in “park” for automatic
transmissions, and lock the ignition, the steering wheel
locks and the gearshift locks. On standard transmission
vehicles just the steering wheel locks.
The function locking energy absorbing column may be
easily disassembled and reassembled, by following
procedures in this section. The serviceman should be
BEFORE COLLAPSE
AFTER COLLAPSE
PLASTIC SLEEVE
WITH BALLS
Fig. 9 — S te e r in g C o lu m n J a c k e t D es ig n
aware that it is important that only the specified screws,
bolts and nuts be used as designated and that they are
tightened to their specified torque. This precaution will
insure the energy absorbing action of the assembly. Care
should be exercised
NOT
to use overlength bolts, as they
may prevent a portion of the assembly from compressing
under impact.
Equally as important is correct torque of bolts and nuts.
Care should be taken to assure that the bolts or nuts
securing the column mounting bracket to the instrument
panel are torqued to the proper specification in order
that the bracket will break away under impact. See the
specifications section at the rear of this manual.
When the function locking energy absorbing column
LIGHT DUTY TRUCK SERVICE MANUAL