It is known to protect the underside of a vehicle with a protective cover formed from stamped sheet metal. The purpose of such a protective cover is to prevent or reduce the consequence of an impact between an object lying on the ground (herein sometimes referred to as a terrain obstacle) and features disposed on the vehicle's underside in circumstances where the ground clearance of the vehicle is insufficient to allow the features to pass thereover without contact. However, conventional steel protective covers are inadequate for multiple reasons including, for example, excessive weight and cost, inability to incorporate intricate or complex shaping, complexity of manufacture due to multiple parts being welded together, and requirement for corrosion protection and/or vibration and noise dampening. As such, a recent trend is to replace the conventional steel protective covers with similar protective covers made substantially of plastic.
Plastic protective covers overcome some of the various shortcomings of conventional steel protective covers, as plastic protective covers are more easily manufactured in complex shapes and are typically of reduced weight and cost as compared with steel protective covers. However, some conventional plastic protective covers fail to adequately protect features on the underside of a vehicle. These conventional plastic protective covers have shapes which are similar to those of the steel protective covers which they replace, but have relatively low tolerance for ground contact with rocks and obstacles having sharp edges. Also, although such protective covers flex readily and generally spring back, if pushed too far, they may tear before taking on much permanent deformation. Additionally, such protective covers offer less resistance to abrasion than steel, and provide reduced impact toughness at low temperatures.
Conventional protective covers are typically attached to a vehicle with fasteners, and the manner of attachment typically does not differ between such protective covers regardless of whether they are formed from metal or plastic. However, as conventional plastic protective covers typically have a similar shape to those conventional metal protective covers which they replace, and as conventional plastic protective covers are unable to absorb and transfer loads to a vehicle in the same manner as can conventional steel protective covers, it is typical that such conventional plastic protective covers can crack and/or creep, particularly at the fastening areas, when the conventional plastic protective covers are exposed to impacts from terrain obstacles. Upon cracking or creeping of a conventional plastic protective cover, the protective cover can lose its ability to protect the underside of a vehicle, the fasteners for the protective cover can lose torque and fall out, the protective cover can vibrate and make noise, and/or the protective cover can become snagged upon terrain obstacles.
Additionally, some conventional plastic protective covers are mounted upon a vehicle with fasteners such that the head of one or more of the fasteners is exposed to damage from contact with underlying objects. The likelihood of damage to such fasteners is escalated when the protective cover is used on an off-road type of vehicle such as an all terrain vehicle (“ATV”). Damaged fasteners can perform inadequately to secure a plastic protective cover to a vehicle and additionally can be difficult to remove during maintenance to features of the vehicle which are shielded by the protective cover. Additionally, damage to fasteners can necessitate replacement of the damaged fasteners, which accordingly results in additional expense to the vehicle's owner. Some conventional arrangements have attempted to resolve this problem such as by using internal wrenching fasteners such as Torx or Allen headed bolts. However, these arrangements are often still susceptible to damage and/or torque loss from ground contact. Other conventional arrangements include a relatively deep pocket formed near the center of the protective cover, wherein a bolt can be inserted into an aperture within this pocket and the head of the bolt can be sufficiently contained within the pocket such that it is unlikely to be damaged by terrain obstacles. However, it is usually difficult to install and remove bolts from such pockets which can thereby make installation and removal of such a protective cover difficult.