TILTING DEVICE FOR A VEHICLE WITH A TILTABLE CAB

Abstract: Tilting device for a vehicle (1) with a tiltable cab (21). The tilting device comprises a double-acting hydraulic cylinder (6) in the cylinder chamber (11) of which a tube (17), which is fixedly connected to the cylinder base (9) and from there extends in the direction of the cylinder head (10) is provided. The piston rod (7) is provided with a blind bore (18), which is open at the cylinder-base-side end of the piston rod (7) and extends in the direction of the other end of the piston rod (7), the tube projecting into the blind bore (18) in the piston rod (7) and being in communication with the chamber delimited by sealing means (19) and the blind bore in the piston rod. This chamber is in communication with the cylinder-head-side working chamber (16) of the cylinder.

Description: Short title: Tilting device for a vehicle with a tiltable cab. The present invention relates to a tilting device for a vehicle with a tiltable cab, a chassis, and hinge means, which connect the cab to the chassis, the cab being tiltable through an angle with respect to the chassis about a hinge axis defined by the hinge means between a driving position and a tilted-forward position, which tilting device comprises a double-acting hydraulic cylinder, which has a cylinder body, which delimits a cylinder chamber closed off by a cylinder base and cylinder head at opposite ends thereof, a piston, which in the cylinder chamber forms two mutually separate working chambers and a piston rod, which is fastened to the piston and projects outwards through a bore in the cylinder head. A tilting device of this kind is known, for example, from US 4,493,386. In this known tilting device, the cylinder base of the double-acting cylinder is provided with two connections for hydraulic lines. The one connection is in communication, via a duct in the cylinder base, with the cylinder-base-side working chamber, the other working chamber is in communication, via a pipe running outside the body of the cylinder, with the other connection arranged on the cylinder base. If hydraulic fluid is supplied to the cylinder-head-side working chamber, this leads to the piston rod sliding in, for which reason the pipe on the outside of the cylinder is referred to by those skilled in the art as a "pull-pipe". A drawback of this known device is that the external "pull-pipe" is susceptible to damage, for example as a result of vibrations. If the "pull-pipe" starts to leak, this results in the cab tilting forwards in an unrestrained and uncontrollable manner when the cab passes its dead centre during tilting forwards, i.e. when the centre of gravity of the cab comes to lie in front of the hinge axis. A further drawback is that the gap between the external "pull-pipe" and the body of the cylinder causes problems in terms of corrosion. A tilting device in accordance with the preamble of claim 1 is also known from FR 24 87 319. In this known tilting device, the "pull-pipe" running on the outside of the cylinder body is absent. Instead of this, the piston rod is provided in the region of its head with two connections for hydraulic lines and two separate ducts are formed in the piston rod. This is done by providing the piston rod with an axial bore and placing a tube of relatively small diameter therein. One connection is in communication with the duct in the tube and, via the tube, with the cylinder-base-side working chamber of the cylinder, and the other connection is in communication with the annular duct between the piston rod and the tube and, via the said duct, with the cylinder-head-side working chambe . Although the tilting device which is known from FR 24 87 319 provides a solution to the problem of damage to the external "pull-pipe", as is known from US 4,493,386, there are also a number of drawbacks associated with this tilting device. For example, in the case of the tilting device in accordance with FR 24 87 319, it is in practice necessary for the cylinder to be fastened to the chassis by the piston rod and to the cab by the cylinder base, in order to avoid undesirably long hydraulic lines to the pump unit. This "upside-down" arrangement of the cylinder is disadvantageous, because there is generally little space available in the area of the underside of the cab for the tilting cylinder and, in the arrangement in accordance with FR 24 87 319, the thick cylinder body is situated in this area instead of the considerably thinner piston rod. A further drawback is that the tilting cylinder which is known from FR 24 87 319 is difficult to realize in production engineering terms and can only be realized at an undesirably high cost price. The design of the free end of the piston rod, where it is necessary for the tube to be extremely well sealed with respect to the encircling duct in the piston rod and to which it is also usually necessary to weld a piston-rod head, is particularly complicated. The object of the present invention is to provide an improved tilting device which is easy to manufacture. This object is achieved by providing a tilting device according to claim 1. The present invention also relates to a vehicle provided with such a tilting device. Further advantageous embodiments and advantages of the invention will emerge from the following description with reference to the exemplary embodiment of the tilting device according to the invention which is illustrated in the drawing, in which: Figure 1 shows a side view of the front part of a vehicle with a tiltable driver's cab, and Figure 2 shows a longitudinal section through the double-acting hydraulic cylinder of the vehicle in Figure 1. Figure 1 shows the front part of a vehicle 1 with a tiltable driver's cab 2. The cab 2 is as usual arranged on chassis 3 and connected to chassis 3 via hinge means 4. The hinge means 4 are designed such that the cab 2 can be displaced through an angle with respect to the chassis 3 about a hinge axis defined by the hinge means 4 between a driving position and a tilted-forward position shown in Figure 1. In the tilted position of the cab 2, maintenance can be carried out on the vehicle 1, in particular on the engine. For tilting the cab 2 forwards and back again, a double-acting hydraulic cylinder 6 is provided, of which piston rod 7 is connected to the cab 2 and cylinder body 8 is connected to the chassis 3. With the aid of the cylinder 6, which furthermore also comprises a hydraulic pump unit which can be actuated manually and/or driven electrically and is fastened to the chassis 3, a force can be exerted on the cab 2, which force is able to tilt the cab 2 forwards out of the driving position and back again. Figure 2 shows the double-acting hydraulic cylinder 6 in detail. The cylinder 6 has an elongate, substantially cylindrical cylinder body 8 with a piston rod 7 which can be moved in a reciprocating, rectilinear manner with respect to the body. The cylinder body 8 has a cylinder base 9 and a cylinder head 10, so that a cylinder chamber 11 is formed. The piston rod 7 projects through a bore 12 in the cylinder head 10 and outwards through sealing means 13 arranged therein. In the cylinder chamber 11, a piston 14, which is connected to the piston rod 7, forms the division between a cylinder-base-side working chamber 15 and a cylinder-head- side working chamber 16. Furthermore, a hollow tube 17, which is fixedly connected to the cylinder base 9 and from there extends in the direction of the cylinder head 10, is provided in the cylinder chamber 11. The piston rod 7 is provided with a central blind bore 18, which is open at the cylinder-base- end of the piston rod 7 and extends in the direction of the other end of the piston rod 7. The free end of the tube 17, which is arranged on the cylinder base 9, projects into the blind bore 18 in the piston rod 7, sealing means 19 being provided in the region of the cylinder-base-side end of the piston rod 7 between the tube 17 and the piston rod 7. The tube 17 is provided with one or more openings 20, which form the connection between the duct in the tube 17 and that part of the blind bore 18 which is separated from the working chamber 15 by the sealing means 19. Furthermore, the piston rod 7 is provided with one or more passages 21, which connect the relevant part of the blind bore 18 to the cylinder-head-side working chamber 16 of the cylinder 6. The cylinder base 9 is provided with a connection 23 for a hydraulic line, which connection leads, via a duct 24, the tube 17, the blind bore 18 and the passages 21, to the cylinder-head-side working chamber 16. The cylinder base 9 is also provided with a connection 26 which leads, via a duct 27, to the cylinder-base-side working chamber 15. Both connections 23 and 26 are intended to be connected to the hydraulic pump unit (not shown) of the tilting device. To tilt the cab 2 shown in Figure l forwards, hydraulic fluid is supplied via connection 26 to cylinder- base-side working chamber 15, while hydraulic fluid flows out of the cylinder-head-side working chamber 16 via the tube 17. When tilting the cab 2 back into the driving position, which corresponds to the piston rod 7 sliding inwards, hydraulic fluid is supplied to working chamber 16 via the connection 23 and the tube 17, while fluid flows out of the working chamber 15 via duct 27 and connection 26. The above-described tilting cylinder 6 can be implemented in a technically simple manner and at low cost.

Claims: CLAIMS 1. Tilting device for a vehicle (1) with a tiltable cab (2), a chassis, (3) and hinge means (4), which connect the cab to the chassis, the cab being tiltable through an angle with respect to the chassis about a hinge axis defined by the hinge means between a driving position and a tilted-forward position, which tilting device comprises a double-acting hydraulic cylinder (6) , which has a cylinder body (8) , which delimits a cylinder chamber closed off by a cylinder base (9) and cylinder head (10) at opposite ends thereof, a piston (14), which in the cylinder chamber forms two mutually separate working chambers (15,16) and a piston rod (7) , which is fastened to the piston and projects outwards through a bore (12) in the cylinder head (10) , characterized in that a tube (17) , which is fixed to the cylinder base (9) and extends towards the cylinder head (10) , is provided, in that the piston rod (7) is provided with a blind bore (18) , which is open at the cylinder-base- side end of the piston rod, in that the tube (17) arranged on the cylinder base projects into the blind bore (18) in the piston rod (7) , in that sealing means (19) are provided between the tube (17) and the piston rod (7) , in that the tube (17) is provided with an opening (20) which is in communication with a space delimited by the sealing means (19) and the blind bore (18) in the piston rod (7) , in that the piston rod (7) is provided with a passage (21) which connects said space to the cylinder-head-side working chamber (16) of the cylinder, and in that the cylinder base (9) is provided with a connection (23) for a hydraulic line to the cylinder-head-side working chamber (16) and a duct (24) which connects the connection (23) to the tube (17) . 2. Tilting device according to claim 1, the cylinder base being provided with first fastening means for fastening to the chassis of the vehicle and the piston rod being provided with second fastening means for fastening to the cab of the vehicle. 3. Vehicle provided with a tilting device according to claim 1 or 2.

Inventors: SONNEBORN LAMBERTUS JOHANNES, SONNEBORN, LAMBERTUS, JOHANNES
Applicants: APPLIED POWER INC, SONNEBORN LAMBERTUS JOHANNES, APPLIED POWER INCORPORATED, SONNEBORN, LAMBERTUS, JOHANNES
Application year: 1997
Main classification: B62D33
IPC codes: B62D33, F15B15