Tie-downs for mounting objects on motor vehicle frames are well known. Such tie downs are often provided for fixed installation to the frame, or to the underside of a vehicle (such as a pick-up truck), for securing a load (such as a camper) to the vehicle frame. Generally, four such tie downs are installed on a vehicle for securing the camper to the pick-up truck's bed at or near all four corners. The currently used tie downs known to me generally include a cantilevered telescoping arm projecting horizontally from a secure position on the vehicle frame. Such prior art tie downs include a rigid support member projecting perpendicularly from an outer sleeve of a cantilevered telescoping arm to fixedly attach to a point on the underside of the vehicle to brace the tie down when the load is secured. Also, such tie downs include a chain having one end pliantly attached to the end of the telescoping arm opposite the frame mount and the other end free for fixedly attaching to the load, such as a camper, to secure it to the vehicle. The load is secured to the vehicle by tensioning the chain using, for example, a turnbuckle. Thus tensioned, the chain is a rigid member unable to relieve sudden loads, such as those caused by shifting of the camper relative to the truck bed. Such sudden load, when not relieved, may exceed the stress-bearing capabilities of the joints mounting the tie downs to the vehicle and may loosen the joints and/or damage either or both of the vehicle and the tie downs. While a spring-loaded turnbuckle is known, it is a separate assembly from the tie down and forms no part of the tie down.
It is a drawback that the currently utilized tie downs must be professionally installed by qualified mechanics, primarily since they are provided from the factory in a single embodiment or configuration which requires drilling of additional mounting holes in the vehicle frame. The drilling of such holes in or adjacent to highly loaded or specially hardened steel frame members requires equipment and a skill level ordinarily available only to the professional installer. Furthermore, the warranties provided by many vehicle manufacturers might be violated or voided by the addition of such holes in the vehicle frame members. Therefore, such considerations severely limit the practical application of the known tie downs, as well as effectively prevent their distribution by mail order.
Undesirably, many tie downs also interfere with use of the vehicle even when the load is not present. This is because rigid support members projecting perpendicularly from the outer sleeve of the cantilevered telescoping arm places the tie down in a position beneath the vehicle in a manner that may interfere with steps, bars and other platforms attached to many vehicles for ease of entry and exit. Fixed position tie downs may also interfere with use of the vehicle off-road, because they are positioned below the vehicle, near the ground, and may encounter brush, stumps, rocks and other low lying obstacles.