Patent ID: 7849641

Claim:
A telescopic undercarriage for raising and lowering a frame, comprising: a base section having a pair of parallel base legs extending from a first end to a second end of the base section, each base leg defining an elongate open-sided channel facing the other base leg, the base section including a first plurality of braces extending between respective upper surfaces of the base legs and a second plurality of braces extending between respective lower surfaces of the base legs, wherein the base legs, first plurality of braces and second plurality of braces collectively define an elongate base section passage; an extendable section telescopically mounted within the base section passage for movement from the second end of the base section between retracted and extended positions and having opposed legs connected by a third plurality of braces extending therebetween, each of the opposed legs of the extendable section being slidably received within a corresponding one of the base leg channels; and a hydraulic drive system connected to the base section and extendable section for extending the extendable section from the second end of the base section and retracting the extendable section into the base section, the hydraulic drive system including a first hydraulic drive cylinder driving a first piston and a second hydraulic drive cylinder driving a second piston, the first hydraulic drive cylinder being mounted within one of the base leg channels and the first piston being mounted within one of the extendable section legs, the second hydraulic drive cylinder being mounted within the other of the base leg channels and the second piston being mounted within the other of the extendable section legs such that when the extendable section is extended, the pistons therein and their mountings serve as reinforcement.