Weight of protection should be as low as possible while ensuring the necessary rigidity and strength. Therefore, its value in the existing protections in the range 7-15 kg, which does not significantly increased load on the front axle. The security appliance casing shape and dimensions of security arrangement in her various holes and mounting locations are determined by design of the car. The holes are needed to: attachment to the body, drain the oil from the engine and gearbox; ventilation. Fixing protection by means of: standard and special bolts, nuts, washers, different, etc. transitional bracket required in the case where power components of the body are high.
Their strength must be sufficient to withstand the load during the impact, legs, made of strips of metal welded to it, traverses a rigid profile, eg pipes. Additional elements of design: cushioning pads mounted on the protection of areas located closest to the engine, gearbox and body elements. This is due to the fact that after the bounce the gap between protection and sump may decrease or become zero. Then, coming into contact with the engine, it makes quite an unpleasant sound (to restore the defense has to turn down the gap down the mount), metal or plastic side wings, set on defense, protecting the engine compartment from dirt. Types of decorative coatings.
Most domestic manufacturers of steel protective covers its products with powder epoksipoliefirnoy paint hot curing. Such coverage is fairly durable in a neat ride. Cheap products for domestic cars paint nitroenamels usual. But even the best quality coverage is not can withstand the mechanical stress, such as running over the curb while parking. Protection of structural steel – relatively cheap material 2-3 mm thick – were most common. Plasticity allows you to have on the product by stamping ribs. Such protection can be easily editing in the case of deformation on impact. Protection of aluminum lighter than steel, but about five times more expensive. So basically They are placed on sports cars, where weight is critical. For the protection of manufacturing is used as a soft alloy aluminum and heat-treated (duralumin) D16T or B95. On the strength of duralumin is not inferior to steel, but a low ductility can not punch ribs. The design of such protection is most often a flat sheet of a thickness of 7-10 mm with a few slight bends and cross-holes for mounting and ventilation. Heat-protection straighten after hitting much harder. Plastic protection made of composite materials consisting of a base – the reinforcing fibers and binder – resin. As a basis more often use of fiberglass, at least – ugletkan (carbon), which is more expensive and less technological. The most resistant composite material for protection – Kevlar fabric, designed for body armor, but its high price limits application. For specific strength of glass and carbon fiber is 1.5-fold, and Kevlar – 2.5 times greater than steel, which allows us to protect better. However, composites do not take concentrated loads. When hit by a sharp object resin crumbles, and fibers that have lost support, break down. Therefore, the thickness of the composite protections must be increased to 8-12 mm, which reduces their weight advantage. Composite protection simultaneously perform the function of the anther, as completely cover the bottom of the engine compartment. Manufacturing technology allows us to give them any shape, but they are more expensive than steel. High strength fibers, increased thickness of the trough and the shape makes them very hard. If the composite crankcase is cracked, it can not be restored.