Locking system for a semitrailer sliding undercarriage

A locking system for mounting on a sliding undercarriage of a semitrailer, the semitrailer pulled by a tractor, the locking system used for securing and releasing the sliding undercarriage from a pair of parallel rails mounted on an underside of the semitrailer, the parallel rails having spaced apart locking pin holes along the length thereof, the sliding undercarriage having spring operated air brakes operated from a pressurized air source on the semitrailer or tractor, the semitrailer having an electrical power source thereto, the locking system comprising:

• a pair of double acting air cylinders with pistons, said air cylinders mounted on the sliding undercarriage and disposed next to the parallel rails;
• locking pins attached to said pistons, a portion of said locking pins inserted into selected locking pins holes in the parallel rails;
• an air pressure switch connected to said air cylinders for allowing operation of said air cylinders and the retracting of said locking pins for the locking pin holes only when air pressure is released to the semitrailer air brakes and the semitrailer brakes are set on the sliding undercarriage;
• and
• an electrically operated 4-way air valve connected to said air cylinders and the pressurized air source on the semitrailer or trailer, said 4-way air valve also connected electrically to the semitrailer's electrical power source and connected to said air pressure switch, said 4-way air valve directing pressurized air to said air cylinders for retracting and extending the pistons in said cylinders, said air pressure switch sensing pressurization or release of air pressure to the semitrailer's air brakes, wherein said air pressure switch and said 4-way air valve are electrically connected to an unlock switch on a control panel mounted on the semitrailer or tractor, said air pressure switch electrically preventing the retracting of said locking pins from the locking pin holes when turning said unlock switch on, if there is an electrical power interruption to the electrical power source on the semitrailer.

A locking system for mounting on a sliding undercarriage of a semitrailer, the semitrailer pulled by a tractor, the locking system used for securing and releasing the sliding undercarriage from a pair of parallel rails mounted on an underside of the semitrailer, the parallel rails having spaced apart locking pin holes along the length thereof, the sliding undercarriage having semitrailer spring operated air brakes operated from a pressurized air source on the semitrailer or tractor, the semitrailer having an electrical power source thereto, the locking system comprising:

• a pair of air cylinders with pistons, said air cylinders mounted on the sliding undercarriage and disposed next to the parallel rails;
• locking pins attached to said pistons, a portion of said locking pins inserted into selected locking pin holes in the parallel rails;
• an electrically operated air valve connected to said air cylinders and the pressurized air source on the semitrailer or trailer said air valve also connected electrically to the semitrailer's electrical power source, said air valve directing pressurized air to said air cylinders for retracting and extending the pistons in said cylinders;
• a fail safe electrically operated air pressure switch, said air pressure switch electrically connected to the semitrailer's electrical power source and connected to the semitrailer's pressurized air source, said air pressure switch electrically interlocked with said air valve for automatically controlling the operation of opening and closing of said air valve during the retracting of said locking pins for the locking pin holes and allowing pin retraction only when air pressure is released to the semitrailer air brakes and the semitrailer air brakes are set on the sliding undercarriage, said air pressure switch sensing pressurization or release of air pressure to the semitrailer's air brakes.