Wheels and armouring
Intended for use in areas where there is a risk from explosive devices, LOCOSTRA wheels are designed to withstand the detonation of 240g TNT without damage that would halt operations. The same blast resistant wheels are mounted at the front and rear.
These large wheels are heavily braced dishes with a tread attached and a large solid rubber wheel in the hub. Designed to allow blast-ventilation and prevent shock transfer to the bearings and chassis, these wheels are original and shockingly robust. On soft ground, it is anticipated that the tread on these wheels may need to be replaced after five blasts. On hard ground, the loss of the tread should not have any great affect on mobility.
Since 2010 we tested seven different wheel designs using a testing and evaluation rig developed on purpose. The rig comprises an Onager like ballistic pendulum allowing each wheel to be compared on the same basis and a flange hosting a shock accelerometer that can also be mounted on the tractor to test wheels also in realistic working conditions.
The testing rig proved to be reliable as one type of wheel was tested in the field with live mines in Jordan in 2011 giving very satisfactory results.
Although completely satisfied with previous results, the research on wheels keep on going with the aim of achieving even more shock absorption. At the moment we are working on the 8th wheel type.
G3 wheel under test with TNT on ballistic pendulum
Compromising between weight, ventilation and a threat that will usually be “low”, the armouring of Locostra is quite simple. The suggested armouring is not intended to provide protection in all possible fragmentation scenarios. It is accepted that this would be impractical on a lightweight air-cooled vehicle.
The armouring comprises:
1. Blast resistant wheels able to vent and absorb shock waves
2. Deflection plates, 3mm thick, made out of mild steel. Empirical evidence suggests that this will be able to stop fragments from common fragmentation mines at ranges over three metres and may deflect those from closer detonations;
3. Kevlar/aramid coverings for exposed hydraulic linkages and hoses that are not vulnerable to blast directly from beneath the wheels - so protected against deflected blast, ricocheting ground fragments and direct fragments from fragmentation mines at a distance of several metres;
4. Flexible Kevlar/aramid curtain to attach to and hang from the three point linkage between the tractor and any toll that may be attached.
In order to avoid predictable weak points where stresses might accumulate, axles of the tractor originally made out of spherical cast iron, were changed into new thicker ones made out of mild steel.