1. Field of the Invention
This invention relates generally to a slider which is used to adjust the suspension of a vehicle longitudinally with respect to the body of the vehicle, and more particularly to an air powered actuator for retracting the locking pins of the slider. In particular, this invention relates to a delay switch for the air powered actuator which prevents the air powered actuator from being operated should the operator of the vehicle momentarily actuate the truck brake.
2. Background of the Invention
Sliders are commonly used to enable longitudinal adjustment of the suspension of a tandem axle trailer relative to the van or body of the trailer. Conventional sliders normally comprise a pair of side rails which are secured to the left and right sides of the van and which extend longitudinally therealong the underside thereof. The suspension of the trailer is carried by a frame which includes left and right slide members which are slidably mounted with respect to the side rails of the van. A plurality of locking pins lock the frame in various positions with respect to the side rails. When it is desired to adjust the suspension of the trailer with respect to the body, the locking pins are retracted to permit the frame to slide with respect to the side rails of the van. However, if the vehicle is not sitting on perfectly level ground, the locking pins may be difficult to pull from their registering openings in the frame and the side rails of the body. Heretofore, the normal procedure for freeing the locking pins was to have one person pull on the actuating arm connected to the locking pins while the driver attempted to jiggle or jog the trailer with respect to the tandem axle, which had been previously locked in place with the air powered emergency brake. The above solution was not satisfactory and an effort to solve the problem is disclosed in U.S. Pat. No. 4,838,566. Although it is believed that the device of the '566 patent makes the problem described above easier to solve, it is still believed that the device disclosed in the '566 patent does not completely solve the problems of retracting the locking pins from their registering openings in the frame and the side rails of the trailer.
The invention disclosed in application Ser. No. 08/195,852 represented a significant advance in the art. However, the invention described in application Ser. No. 08/195,852 did not include any means which would indicate to the vehicle operator that the locking pins had been completely retracted. Further, the invention of application Ser. No. 08/195,852 did not include any means for indicating the relative position of the vehicle body with respect to the vehicle suspension as the vehicle body is being moved with respect to the vehicle suspension.
The invention disclosed in the co-pending application Ser. No. 08/243,984 solved the problems of the prior art in that it provided a means for indicating to the vehicle operator that the locking pins had been completely retracted and included means for indicating the relative position of the vehicle body with respect to the vehicle suspension as the vehicle body is being moved with respect to the vehicle suspension.
Although the co-pending applications are believed to represent significant advances in the art, it has been found that it was possible, in some situations, for the locking pins to be inadvertently retracted while the vehicle was being moved. Such a situation may represent a potentially dangerous situation although to date, applicant is not aware of any accidents which have occurred due to the locking pins being retracted while the trailer was moving.
Application Ser. No. 08/295,203 described an improvement over U.S. Pat. No. 4,838,566 and applicant's co-pending applications, in that the locking pins may not be pulled from the registering openings in the frame and the side rails of the trailer unless the trailer emergency brake is in its set and locked position. However, it has been discovered that in certain situations wherein the truck was being "hooked-up" to the trailer, with the trailer emergency brake in its set and locked position, the air powered actuator could be inadvertently actuated upon the truck operator depressing the truck brake pedal which would actuate the trailer brake light circuit, thereby supplying electrical current to the air powered actuator. This situation only occurs when the trailer air lines and trailer electrical cables have been connected to the truck air hoses and truck electrical system prior to the truck operator beginning the actual mechanical connection of the fifth wheel of the truck to the king pin of the trailer.