JPH0336760B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a three-part mast for handling materials.

Forklift trucks that should be able to work inside low spaces, but at the same time have a high lifting height, should be equipped with a three-part mast, i.e. a mast with three pairs of guides. can be made appropriately. Furthermore, the mast should be designed as a free-lifting mast. That is, the design should be such that the fork rear is raised to its highest position before the movement of lifting the guide is started.

The object of the invention is to provide a simplified lifting system for a three-part mast by arranging the operating cylinder or cylinders in different ways and by pulling the rope or chain in different ways for the lifting movement. The goal is to provide the following. If two cylinders are used in a lateral arrangement, allowing the piston rods to extend in opposite directions in a telescoping manner,
Adequate visibility can be obtained through the mast.

The mast according to the invention has a first pair of guides supported by the tracks and commonly articulated to the tracks for so-called tilting movement. A second pair of guides is arranged to be vertically movable within said first pair of guides. A third pair of guides is vertically movable within said second pair of guides. A fork carrier is controlled by said third pair of guides and is arranged to be movable in a vertical direction.

A feature of the invention is that one or more operating cylinders for the lifting movement are arranged in the upper half of the second pair of guides,
Furthermore, the length of the operating cylinder is half that of the guide. When only one operating cylinder is used, this cylinder is made with two pistons and one piston rod that can extend upwards and one piston rod that can extend downwards. If several actuating cylinders are used, a different actuating cylinder can be used for each upwardly extendable piston rod and downwardly extendible piston rod. Two separate chain or rope systems are used for the mast.
A first chain or rope attaches one end thereof to the top of the first pair of guides. A first chain extends downwardly through a pulley wheel (referred to herein as a pulley) on a piston rod and extends upwardly over a third pair of guides. from which it runs downwards to the fork carrier. The first chain attaches its other end to the fork carrier. a second chain or rope attaches one end thereof to a second pair of guides;
It extends over a sheave on a piston rod that can be extended upwardly, and its other end is attached to the lower part of the third pair of guides.

The present invention will be described in further detail below with reference to the accompanying drawings.

The first pair of guides 1 is a track (not shown)
is articulated with. A second pair of guides 2 is guided by a first pair of guides 1. A third pair of guides 3 is guided by a second pair of guides 2, and a fork carrier 4 is controlled by a third pair of guides 3. An operating cylinder 5 is fixedly joined to the upper half of the second pair of guides 2, the length of which operating cylinder 5 being approximately half the length of the guides 1, 2, 3. The operating cylinder 5 is of the type with two piston rods 6, 7 which can extend in opposite directions. These piston rods support sheave wheels 8 and 9, respectively. At the top of the third pair of guides 3 there is a sheave wheel 10. A rope or chain 11 is attached to the top of the first pair of guides 1 and to the fork carrier 4. rope 1
1 extends around pulley wheels 8 and 10.
A rope or chain 12 is attached to the bottom of the second pair of guides 2 and the third pair of guides 3.
The rope 12 extends around a pulley 9.

The operating cylinder 5 can be assembled in the manner shown in FIGS. 4 and 5 and can be constituted by a cylinder 13 fixedly connected to the second pair of guides 2. The operating cylinder 5 houses a piston rod 6 which can be extended downwardly and a cylindrical piston rod 7 which can be extended upwardly. In the retracted position, the piston rod 6 is inserted into the piston rod 7. The cavity 14 in the actuating cylinder 5 is supplied with pressure medium through a conduit 15 . During operation, the force acting on piston rod 7 has twice the magnitude of the force acting on piston rod 6. By choosing the area of the piston rod 6 to be somewhat larger than half the area of the piston rod 7, it is possible to move the fork carrier 4 to its upper position before the guides 2 and 3 are raised. Alternatively, it may be appropriate to arrange a fixing device which fixes the fork carrier 4 in its upper position and keeps it fixed in this position during the raising and lowering of the guide pair 2 and 3. When the fork carrier 4 has been raised to its upper position shown in FIG. 2 by extending the piston rod 6 telescopically, the pressure in the cavity 14 increases until it overcomes the force acting on the piston rod 7. do. The piston rod 7 is extended and the fork carrier 4 is raised together with the guide pair 2 and 3. (See FIG. 3.) When lowering, first the guide pairs 2 and 3 are lowered with the fork carrier 4 positioned at the highest position relative to the guide pair 3. When the guide pairs 2 and 3 have been lowered to their lower position, the fork carrier 4 is lowered relative to the guide pair 3.

The three-part lifting mast with cylinders described herein allows the fork carrier to operate at a constant lifting speed throughout the lifting movement. If the cylinder area of the piston rod 7 is chosen to be approximately twice the area of the piston rod 6, the pressure of the pressure medium remains largely constant throughout the upward movement. Further, since the operating cylinder 5 is fixedly joined to the upper half of the second pair of guides 2, and the length of the operating cylinder 5 is approximately half the length of the guides 1, 2, and 3, the fork carrier 4 is A free lift can be obtained over almost the entire length of the guide 3, and furthermore, when the operating cylinder 5 extends downward, the pulley 8 does not protrude below the guides 1, 2, and 3.

[Brief explanation of drawings]

Figures 1 to 3 show the three-part mast in different operating states, while Figures 4 and 5 show the double piston rod with the piston rod in the retracted and extended positions. 1 shows an operating cylinder with a DESCRIPTION OF SYMBOLS 1...First pair of guides, 2...Second pair of guides, 3...Third pair of guides, 4...Fork carrier, 5...Operation cylinder, 6, 7...Piston rod, 8, 9... ... Sheave wheel, 11, 12... Rope or chain.

Claims (1)

Claims: 1. A three-part mast for handling materials, preferably mounted on a forklift truck, comprising a first pair of guides 1 mounted on the truck;
a second pair of guides 2 guided by the first pair of guides 1 and capable of vertical movement; and a third pair of guides 3 guided by the second pair of guides 2 and capable of vertical movement and a fork carrier 4 guided by a third pair of guides 3 and adapted to move vertically, one or more operating cylinders 5
is fixedly attached to the upper half of the second pair of guides 2. The length of the operating cylinder 5 is the same as that of the guides 1,
approximately half of 2, 3, said operating cylinder is equipped with an upwardly and downwardly extendable piston rod 6, 7 with sheaves 8, 9 for ropes or chains (11, 12); A first rope or chain 11 is attached to the upper part of the first pair of guides 1 and extends over a pulley 8 on a piston rod 6 which can extend downwardly and extends upwardly to the third pair of guides 3.
and a second rope or chain 12 is attached to the second pair of guides 2; A three-part mast, characterized in that it is attached to the lower part of the third pair of guides 3, which extend over a pulley 9 provided on a piston rod 7 that can be extended upwards. 2. A mast according to claim 1, in which the mast comprises two separate actuating cylinders 5 with one piston rod 6 that can be extended downwardly and one piston rod 7 that can be extended upwards. The mast is characterized by: 3. A mast according to claim 1, in which the mast comprises an operating cylinder 5 with one piston rod 6 that can be extended downwardly and one piston rod 7 that can be extended upwards. A must-have feature. 4. The mast according to claim 3, characterized in that the area of the piston rod 7 that can be extended upwardly is smaller than twice the area of the piston rod 6 that can be extended downwardly. mast.