EQUALIZING BEAM SUSPENSION (HENDRICKSON)
DESCRIPTION
Tandem drive axles require a special suspension which
permits flexibility between the axles but still withstands
rugged usage with long service life. The equalizing beam
type suspension system described herein embodies
these required characteristics. The types of Hendrickson
equalizing beam suspensions used on International
trucks are the leaf spring type and rubber load cushion
type.
LEAF SPRING TYPE
The leaf spring type suspension (Figure 1) uses
semielliptic leaf springs to cushion load and road shocks.
The springs are mounted on saddle assemblies above
the equalizer beams and are pivoted at the front end on
spring pins and brackets. Rear ends of springs have no
rigid attachment to spring brackets, but are free to move
forward and backward to compensate for spring
deflection.
Figure 1 -- Equalizing Beam Suspension
(Leaf Spring Type)
The equalizing beams utilize the "lever" principle to
distribute the load equally between axles and to reduce
the effect of bumps and road irregularities. The torque
rods permit complete absorption of torque, which is the
tendency of the axles to turn backwards or forward on
their axis due to starting or stopping inertia. The cross
tube connecting the equalizing beams assures correct
alignment of the tandem and prevents damaging load
transfer.
RUBBER CUSHION TYPE
This type of suspension system (Figure 2) uses rubber
cushions in place of leaf springs to absorb load and road
shock. On these units, rubber cushions are mounted on
a saddle assembly at each side. Positive mounting
between frame brackets and the suspension unit is
secured by four rubber-bushed drive pins, one each of
which passes through a rubber cushion.
Figure 2 - Equalizing Beam Suspension (Rubber
Cushion Type)
Without load, the unit rides on the outer edge of the load
cushions. As the load increases, the crossbars of the
cushions are progressively brought into contact to absorb
the additional load. Cushioning and alignment are
accomplished by the four drive pins encased in rubber
bushings. The bushings permit the drive pins to move up
and down in direct relation to movement of the load
cushions. See Figure 3.
1 INTEGRAL DRIVE PIN WITH BRACKET
2 NO LOAD POSITION
3 RUBBER CUSHIONS
4 FULL LOAD POSITION
6 RUBBER DRIVE PIN BUSHING
7 BUSHING RETAINER CAP MT-2*03A
Figure 3 - Sectional View. Rubber
Cushion Type Suspension
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