SPRINGS, SHOCK ABSORBORSSPRING ASSEMBLIESDESCRIPTIONVarious types of spring assemblies used on IH vehiclesare described below.Constant RateConstant rate springs are leaf-type spring assembliesthat have a constant rate of deflection. For example, if227 Kg (500 pounds) deflect the spring assembly 2.54cm (1 inch), then 454 Kg (1000 pounds) would deflectthe same spring assembly 5.08 cm (2 inches). Thus, therate of deflection is constant.Constant rate springs are mounted to the axle with U-bolts, nuts and lock washers. The front end of the springis mounted to stationary bracket. The rear end of thespring is mounted to a spring shackle. The shackleallows for variations in spring length during compressionand rebound.This type of spring assembly is used in both front andrear axle applications on IH vehicles.Figure 1 and 2 show typical views of constant rate springassembly applications.Figure 1 - Front Axle Application (Constant Rate)Figure 2 - Rear Axle Application (Constant Rate)Tapered LeafTapered leaf springs are leaf type spring assemblieswhich are thicker in the center than the ends. Thisdesign results in a fewer number of leafs, providinglighter weight.Taper leaf springs are mounted to the axle with U-bolts,nuts and lock washers. The front end of the spring ismounted to a stationary bracket. The rear end of thespring is mounted to a spring shackle. The shackleallows for variations in spring length during compressionand rebound.Figure 3 illustrates a Taper leaf assembly.Figure 3 - Taper Leaf Spring AssemblyAuxiliary SpringsAuxiliary springs are leaf-type spring assemblies usuallymounted on top of the vehicle rear spring assemblies.Auxiliary springs are used only when the vehicle is underheavy load. The auxiliary spring assumes part of theload by contacting special brackets attached to frame railslides when the load is sufficient to compress the vehiclerear spring assemblies to the point of contact.Figure 4 illustrates an auxiliary spring assembly.Figure 4 - Auxiliary Spring AssemblyProgressive (Vari-Rate)Progressive (Vari-rate) springs are leaf-type springassemblies with a variable deflection rate obtained byvarying the effective length of the spring assembly. Thisis accomplished by using a cam-type bracket. As thespring assembly deflects, the point of contact on thebracket moves toward the center of the spring assemblyshortening the effective length, Figure 5.Vari-rate spring assemblies also incorporate aprogressive feature in that the bottom spring leaves areseparated at the ends. AS the spring assembly deflects,these leaves comes in contact providing increasedcapacity and stiffness.CTS-4168 - Page 2
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