SE420402B - LIFT MAST FOR FORK TRUCK - Google Patents

Description

7907073-6 Figure 6 shows a part of the lifting mast and figure 7 shows a longitudinal section in direction B-B in figure 5 through a part of the lifting mast.

The invented mast consists of a number of composite sections which in one plane are rotatable relative to each other so that they can be rotated in one direction so that they form a straight mast. In the other direction, the sections are rotatable relative to each other so that they can be guided with guide rails after a certain curved path, for example under and behind the driver's seat on the forklift as shown in figure 2.

The guide rails 18 are not raised to a greater height than the driver has a clear field of view over them. At the forks in the lowered position, the largest part of the mast is thus pushed in below and at the rear of the forklift.

Under the influence of payload, the mast remains vertical and straight during a hoisting or firing process. From a safety point of view, however, a raised mast should be completely rigid even in the direction in which the mast for the lowered position is articulated.

A device for effecting such a locking between respective sections will be described later.

The lifting mast 1 is composed of a number of rotatably assembled sections 2. The uppermost section 2 is rotatably connected to a special section 3 which carries lifting forks 4. ii When a mast is pushed up it is ensured that each section 2 is firmly anchored to connecting section by means of a control unit 5. A spring 6 in the control device presses a plunge 7 in the control device into a hole 8 on the adjacent section. The plunger 7 is provided at the opposite end with rollers 9. When lowering a mast, the interlock between the respective mast sections is lifted - as rollers 9 are actuated by guide rails 10, plungers 7 being displaced axially until they are released from the holes 8. The guide rails 10 are designed retracted, whereby interlocking between the respective sections is canceled, during the process when the mast sections change direction.

Lifting or lowering movement for a lifting mast can be achieved in several different ways. For normal lifting heights, the maneuvering movement can be effected with a telescopic hydraulic cylinder of known design as shown by a dashed contour line in figure 1.

Claims (4)

7907073-6 For high-lift masts, maneuvering movement can be achieved by performing the sections with a rack. Such an embodiment is shown in Figures 3, 4, 5 and 6. A U-shaped mast section 11 is provided with mounting ears 12 and teeth 13. Through the mounting ears 12 and mounting holes in the connecting section 14 there are shafts 15 with rollers 16. The rollers 16 are guided of rails 18 which are not raised to a greater height than a driver has a clear view of them. A control unit 5 connects inside the mast sections ll. The plunger 7 of the control device is actuated by rollers 9 of guide rails 10. Vertical movement is effected by means of gears 17 which are in engagement with teeth 13. The gear 17 is rotated by means of a machinery which is not shown. Under the influence of load, the drawbar ears 12 will be affected by vertically directed tensile forces and the contact surfaces at the front edges 19 of the sections will be affected by vertically directed compressive forces. During a hoisting process, the sections will also be interlocked by the plungers 7 as they leave the respective guide rails. Within the scope of the invention, interlocking between the mast sections can be effected in several other ways, for example by means of a tensioned line or chain which runs parallel to the mast at the printed side 19 of the sections. Two or more masts can be arranged next to each other. The deflected part of a mast can be guided along different paths or rolled up. Patent claims Lifting mast for forklift (1), consisting of a number of sections (2, 11) rotatably connected about parallel axes (15), the rotational movement between the sections in one direction being stopped by contact surfaces (19) so that the section together in one plane form a straight mast while the sections in the other direction in the same plane can be rotated relative to each other to a right or other mutual angle, characterized in that the lifting mast comprises controls (5) springs (6) and plungers (7 ) which are operated by guide rails (10) so that the sections for the remaining mast are locked to each other. Lifting mast according to claim 1, comprising sections made with racks (13), characterized in that the adjustment of the height position takes place by means of gears (17) in engagement with racks. 3. Lifting mast according to claim 1, characterized in that the lifting mast is deflected at a low working position in a path almost horizontal under the associated forklift. Lifting mast according to claim 1, characterized in that it comprises a stretched chain or a rope which, when placed at the printed side (19) of the sections, prevents mutual rotational movement between the sections for the remaining mast.