SPRINGS, SHOCK ABSORBORS
SPRING ASSEMBLIES
DESCRIPTION
Various types of spring assemblies used on IH vehicles
are described below.
Constant Rate
Constant rate springs are leaf-type spring assemblies
that have a constant rate of deflection. For example, if
227 Kg (500 pounds) deflect the spring assembly 2.54
cm (1 inch), then 454 Kg (1000 pounds) would deflect
the same spring assembly 5.08 cm (2 inches). Thus, the
rate of deflection is constant.
Constant rate springs are mounted to the axle with U-
bolts, nuts and lock washers. The front end of the spring
is mounted to stationary bracket. The rear end of the
spring is mounted to a spring shackle. The shackle
allows for variations in spring length during compression
and rebound.
This type of spring assembly is used in both front and
rear axle applications on IH vehicles.
Figure 1 and 2 show typical views of constant rate spring
assembly applications.
Figure 1 - Front Axle Application (Constant Rate)
Figure 2 - Rear Axle Application (Constant Rate)
Tapered Leaf
Tapered leaf springs are leaf type spring assemblies
which are thicker in the center than the ends. This
design results in a fewer number of leafs, providing
lighter
weight.
Taper leaf springs are mounted to the axle with U-bolts,
nuts and lock washers. The front end of the spring is
mounted to a stationary bracket. The rear end of the
spring is mounted to a spring shackle. The shackle
allows for variations in spring length during compression
and rebound.
Figure 3 illustrates a Taper leaf assembly.
Figure 3 - Taper Leaf Spring Assembly
Auxiliary Springs
Auxiliary springs are leaf-type spring assemblies usually
mounted on top of the vehicle rear spring assemblies.
Auxiliary springs are used only when the vehicle is under
heavy load. The auxiliary spring assumes part of the
load by contacting special brackets attached to frame rail
slides when the load is sufficient to compress the vehicle
rear spring assemblies to the point of contact.
Figure 4 illustrates an auxiliary spring assembly.
Figure 4 - Auxiliary Spring Assembly
Progressive (Vari-Rate)
Progressive (Vari-rate) springs are leaf-type spring
assemblies with a variable deflection rate obtained by
varying the effective length of the spring assembly. This
is accomplished by using a cam-type bracket. As the
spring assembly deflects, the point of contact on the
bracket moves toward the center of the spring assembly
shortening the effective length, Figure 5.
Vari-rate
spring
assemblies
also
incorporate
a
progressive feature in that the bottom spring leaves are
separated at the ends. AS the spring assembly deflects,
these leaves comes in contact providing increased
capacity and stiffness.
CTS-4168 - Page 2
