TESTING
ENVIRONMENTAL TESTING To successfully navigate through water, the components underneath military vehicles must be completely sealed off to external elements to keep dust, grit and salt out of components, and lubrication in. This is where environmental testing comes in. For military applications, this testing is arguably just as important as the physical testing. It is vital that every part of the steering system is able to handle water exposure, changes to temperature and humidity variance. Military vehicles endure extreme conditions during their lifetime, taking on temperatures as low as -40ºC, without resulting in high torque steering. Every test is designed to replicate
the real conditions a vehicle will face, to ensure the vehicle is fit for purpose. While all military vehicles can differ, when it comes to the environmental testing of military-grade steering components, there are some crucial parameters to consider. Pailton Engineering uses a salt
spray test rig, where up to six steering parts at a time can be tested dynamically against salt spray, at varying temperatures. This rig is a large container with a rotary arm that controls the movement of steering components, normally at a rate of one cycle every three seconds - one cycle representing one turn of the steering wheel. The test can use varying
concentrations of salt, with higher concentrations being for the more extreme applications, as often seen in the military vehicle industry. So, what can you expect to see from
a test like this? The results will illustrate changes in torque, rate of corrosion, overall effect of grit on the vehicle and its steering system, as well as any potential for water ingress. Of course, the best possible result for this test to show is that these parts are capable of working in these conditions at low temperatures. The same test rig can also be used
to test the system against other factors, such as deep water. During rotary submersion, the parts are fully submerged in water. Ultimately, if a part can endure underwater movement at one cycle every three seconds, at varying temperatures, without corroding or failing, then the vehicle manufacturer can be confident in putting those steering parts in a military vehicle for use in the end environment. There are alternatives that can be
explored to improve the performance of a part. From different finishes, to upgraded sealing and greases, there has been plenty of scope for development in recent years. With steering components taking on new and improved design features and passing rotary submersion testing, comes new opportunities for high-performance extreme vehicles taking on deep water wading. One customer’s request led to the
production of the next generation of bevel boxes, needed for vehicles
A physical test rig, this one is rated up to 400kN
carrying out long journeys at low temperatures with high levels of moisture and grit. Bevel boxes are a pivotal component of a steering system, transmitting torque through 90° in order to provide a compact steering system package. After improving on the design
features of the previous bevel box, with a serration cover and alternative grease, the bevel box took on a 56 week long environmental test programme. Operated at a rate of one rotary cycle every three seconds continuously and submitted to salt exposure and temperatures of -40°C for four hours every week, the new design features were validated. External validation showed the
generation three bevel box conformed with ingress protection codes IP66 and IP67, which is great news for the military industry.
WHAT DOES THE FUTURE HOLD? Warfare is changing, and governments are being forced to adapt their military vehicle fleets to keep up. The next five years will see the rapid adoption and adaptation of intelligent technology and applying this to disruptive military applications. Some military vehicle manufacturers
are receiving orders worth more than $195 million from the US army, take the Joint light Tactical Vehicle (JLTV) program for example. These vehicles will displace one third of the Marine Corps high mobility multipurpose wheeled vehicles (HMMWV) in 2019. The impressive payload, miles range and high-speed military vehicles in general explains why this industry is generating so much interest. Some of these large vehicle orders are set to have planned operating capability by the end of 2020. New technology could improve the
survival rates of personnel - whether as a result of increased agility, autonomous resupply or high-performance steering, and it’s this notion that makes the implementation of such technology incredibly important. ●
Nick Jordan is Technical Engineering manager at Pailton Engineering
www.pailton.com
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www.engineerlive.com
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