The Heavy Duty live rear axles in commercial vehicle helps to transmit the drive to the rear wheels and also carries vehicle load. The rear axle along with wheel assembly consists of axle casing, differential unit, half shafts, wheel hub, brake drum, brake chamber and wheels. It is one of the major safety critical element in any commercial vehicle. Based on the suspension type, rear axle housing also carries V rod & radius rod mountings & Spring Seat /Wear pad / Rubber Bolster (in case of bogie suspension).
This paper abbreviates the contribution of bogie suspension seating configurations & V-rod Forces on life of heavy duty bogie rear axle casing. In-service DRT hot spot observations were reported on heavy duty rear axle on few models with bogie suspension. In order to find the root cause, devising a proper testing and analysis method is of prime importance. An extensive effort was made to device test methodology based on customer application and field visits.
The test methodology includes Static articulation test cases, Dynamic Pot hole and speed breaker events along with Road Load Data simulation. Vehicle with various suspension component combinations, equipped with Strain gauged Rear axles &V rod, radius rods, were tested for above test cases on road simulator and measurement of axle strain, V-rod and Radius rod forces, Axle displacements were carried out. Vehicle level Iterations with Various combinations of suspension & Seating assembly experimented to understand the Stress levels at hotspot locations.
Road load data & desired articulation conditions simulated using Six poster road simulator at vehicle level. Axle vertical force, V-rod, radius rod force measurement also carried out to understand the effect of loading distribution pattern. Resolved V rod force calculation methodology adopted for comparison strain Hysteresis trend. Hysteresis between axle vertical force and strain also analyzed to observe the Trend.
The above analysis resulted in identification of Load case and Suspension allied components contribution to hotspot. This experiment holistically provides solution for selection of right combination of Rear axle, suspension & allied seating parts for higher fatigue life of rear axle.