Patent ID: 8245805
Filing Date: 2012-08-21
Classification: B62D,F15B

Abstract:
1. Vehicle cab tilting device for a vehicle with a tiltable cab, a chassis and pivot means which connect the cab to the chassis, in which the cab can be tilted through an angle with respect to the chassis between a driving position and a forwardly tilted position, in which the tilting device comprises: a pump having at least one pump port for delivering pressurized hydraulic fluid, a reservoir for hydraulic fluid, a hydraulic tilting cylinder for tilting the cab, which tilting cylinder has a first and a second connection port, in which the tilting cylinder is a multistage telescopic hydraulic tilting cylinder with an outer telescopic part, at least one intermediate telescopic part, and a central telescopic part, each intermediate telescopic part and the central telescopic part being displaceable with respect to one another and to the outer telescopic part, in which the outer telescopic part has a cylinder tube which is provided with a bottom at an axial end and a head with a bore hole at the other axial end, in which each intermediate telescopic part is arranged in the cylinder tube of the outer telescopic part and is provided with a cylinder tube including a piston rod and a piston part, in which the intermediate telescopic part has a bottom at an axial end and a head with a bore hole at the other axial end, such that the piston rod of an intermediate telescopic part extends through the bore hole in the head of a surrounding telescopic part and the piston part delimits a bottom-side chamber and an annular rod-side chamber in the surrounding cylinder tube, in which the central telescopic part has a piston rod and a piston part, such that the piston rod extends through the bore hole in the head of the surrounding intermediate telescopic part and the piston part delimits a bottom-side chamber and an annular rod-side chamber in the tubular piston rod of the surrounding intermediate telescopic part, in which the first connection port is provided in such a manner that in each position of the telescopic cylinder it is in direct communication with the bottom-side chamber in the outer telescopic part, in which the second connection port is provided in such a manner that in each position of the telescopic tilting cylinder it is in direct communication with the rod-side chamber in the tubular piston rod of that intermediate telescopic part which directly surrounds the central telescopic part, in which furthermore a passage is present in the bottom of each intermediate telescopic part, which passage in each position of the telescopic tilting cylinder extends between the bottom-side chamber in the respective intermediate telescopic part and the bottom-side chamber of the surrounding telescopic part, in which furthermore a through-passage is present in each intermediate telescopic part which, at one end, ends at the annular rod-side chamber in the surrounding telescopic part and which, at the other end, ends at an opening on the inner side of the respective intermediate telescopic part, which opening is arranged in such a manner that, in a retracted position of the telescopic part situated inside, the respective opening is in direct communication with the annular rod-side chamber in the respective intermediate telescopic part in which the opening is provided, and, in an at least partly extended position of the telescopic part situated inside, is in communication with the bottom-side chamber in the respective intermediate telescopic part in which the opening is provided, in which, in order to extend the telescopic tilting cylinder, at least the first connection port is connected to the pump port, so that from the retracted position the one or more intermediate telescopic parts together with the central telescopic part extend first, until the outermost intermediate telescopic part reaches its maximum extended position, after which all remaining telescopic parts together extend further, which process is repeated until the central telescopic part is also finally extended with respect to the surrounding intermediate telescopic part, and in which, in order to retract the telescopic tilting cylinder, the second connection port is connected to the pump port and the first connection port to the reservoir, so that from the extended position the central telescopic part retracts first, until the piston part thereof passes the opening of the through-passage and thus connects the piston-rod-side chamber to which the second connection port is connected to the piston rod-side chamber of the surrounding telescopic part, so that the central telescopic part together with the surrounding intermediate telescopic part is then retracted, which process is repeated when two or more intermediate telescopic parts are present, until the one or more intermediate telescopic parts and the central telescopic part are completely retracted.