The automobile service ramp has developed through the years from simply:
A. an inclined plane block with a flat portion made from large pieces of wood, for example, sections of railroad ties, to PA1 B. truss like structures, to PA1 C. my recent invention of the stamped, welded ramp disclosed in co-pending applications, Ser. No. 520,566, now Pat. No. Des. 239,610 and 503,947, now U.S. Pat. No. Des. 237,162.
The stamped automobile service ramp has several advantages including simplicity and reduction in cost, combined with additional safety. Because the ramp is of a single piece of metal, there is no danger of failure of the ramp by reason of failure of fastening devices such as loosening of bolts, shearing of rivets and the like, or improper assembly or maintenance by the user. To obtain sufficient strength in initial designs of stamped ramps, increased thickness material was required.
One other limitation on existing service ramps of all types has been the lack of any clear indication to the driver, while driving his vehicle up onto a ramp, that the tire has reached the final, desired position. Even stops which have been present at the end of the rest portion can easily be driven over and the vehicle driven off the ramp. This is particularly a problem with lower profile low pressure tires which do not give a feeling to the driver of striking any small stop or obstruction.
One other difficulty has been that ramps of the unitary type do not have handles which were present in the old truss type of ramps where any portion of the truss can be grasped to carry a ramp.
Typically stamped or formed ramps have employed flat cross section ramp surfaces with upstanding side walls. The side walls are intended as guides for the tires and to act like a truss on each side to give added strength.