M113-SUPPORT ARM BUSHING UPGRADE
The ADF (Australian Defence Force) was in search of a material that would not wear down or damage the support arm trunnion of the M113 armored personnel carrier, as its current material was causing excessive wear and frequent vehicle repairs. The M113s needed to take heavier loading, tolerate higher speed and last more than 10,000 km (the vehicles need to remain in service until 2020).
Over the years the ADF’s M113 fleet has used several different materials for their support arm bushings, including fabric-based, oil-lubricated, bronze bearings and plastic bearings. Not only did the bearings experience an excessively high wear rate, but most of the trunnions on the support arm were damaged. Some details on the M113 follow below:
- Vehicle weight under normal operation: approx. 10 to 13 metric tons for all variations
- Maximum combat laden weight: 13 metric tons
- Vehicle speed: max at 75 km/hr on open road
- Number of roadwheels: 10
- Temperature: -40°F to 302°F (-40°C to 150°C)
- Life requirement: >10,000 km
Lancer recommended Arlon® 1555, a proprietary blend of thermoplastic material (lubricated and carbon filled), because it had been battle tested as road arm bushings on the Bionix (25 ton infantry fighting vehicle) and the AMX 13 SM1 (17 ton light tank), clocking over 6,500 km in service.
EVALUATION BY THE ADF
A total of six different bushings were selected for trials on two M113 vehicles in Victoria, Australia.
The bushings included:
- The original bushing as a basis for comparison (Reinforced Tetrafluoroethylene)
- A bronze bushing
- Arlon® 1555
- Three other different plastic materials
The evaluation was divided into two phases: the first phase (initial evaluation) ended after the vehicles clocked between 1,000 to 1,500 km, and the second phase ended after they clocked 5,400 km. Arlon 1555 was one of only three bushings left after the first phase. The bushings were still serviceable at the end of testing, and the trunnions were in almost perfect condition. Using the total distance traveled (5,424 km), the wear rate for the Arlon bushing can be estimated at between 0.026 mm/1000 km and 0.067 mm/1000 km. From the results, we estimated that the bushings can last for at least 20,000 km before replacement.
Based on these results, the ADF put the bushings through a more extreme trial in Darwin, Australia. At the trial, five support arm assemblies were fitted with Arlon 1555 bushings and put through operations in the field until failure.
The trials performed by the ADF highlight the capabilities of Arlon 1555 in extremely harsh environments. Arlon 1555 delivers strength and wear properties critical for the hostile conditions prevalent in the defense arena.
© 2007 Lancer Systems all rights reserved LS.DS.007-1/07 Arlon® is a registered trademark of Greene, Tweed & Co. All rights reserved. All other trademarks are property of their respective owners.
|Hardness, Shore D, Points||D2240||87|
|Hardness, Rockwell M, Points||D785||98|
|Tensile Break Strength, psi||D638||21,200|
|Tensile 0.5% Secant Modulus, psi||D638||1,650,000|
|Compressive Strength @ Break, psi||D695||24,600|
|Deformation Under Load, %||D621||0.10|
|Flexural Strength, psi||D790||33,000|
|Flexural 0.5% Secant Modulus, psi||D790||1,400,000|
|Shear Strength, Axial, psi||D732||13,000|
|Shear Strength, Transverse, psi||D732||10,000|
|Heat Deflection Temperature @ 264 psi, ºF||D648||>600|
|Coefficient of Thermal Expansion < 300ºF, 10-6 in./(inºF)||D696||8|
|Coefficient of Thermal Expansion > 300ºF, 10-6 in./(inºF)||D696||17|
|Coefficient of Dynamic Friction, PV = 12,600 psi-ft/min||G77||0.17|
|Wear Factor, 10-10 in.3-min./(lb.-ft.-hr.)||G77||65|
Note: Properties of Arlon 1555 are anisotropic. The published properties, unless otherwise noted, are measured in the axial flow direction of molded test specimens. Strength and stiffness, therefore, are at a maximum, while elongation and thermal coefficient of expansion are at a minimum.