EP0286615A1

EP0286615A1 - Articulated jack

Info

Publication number: EP0286615A1
Application number: EP88850114A
Authority: EP
Inventors: Toivo Mäkelä; Raine Vierto
Original assignee: Vierto Raine
Current assignee: Vierto Raine
Priority date: 1987-04-10
Filing date: 1988-03-30
Publication date: 1988-10-12
Also published as: FI77632B; FI871591A; FI871591A0; FI77632C

Abstract

Articulated jack consisting of a frame (1) placed on a base, e.g. a floor, a lifting table (2) and articulated levers (3,4) located between the frame and the lifting table and movable by means of a pressure cylinder (5). The pressure cylinder (5) is placed in the horizontal plane of the frame and the force of the cylinder is applied between one (6) of the end beams of the frame and a connecting beam (7) which connects the movable lower ends of the articulated levers (3).

Description

The present invention relates to an articulated jack consisting of a frame placed on a base, e.g. a floor, a lifting table and articulated levers which are located between the frame and the lifting table and movable by means of a pressure cylinder.
A disadvantage with known types of articulated jack of this category is the fact that their size and weight are in proportion to the lifting capacity. For example, in articulated jacks used to lift up cars, the height of the jack in the lowest position has to be about 30 cm when a lifting capacity of two tons is required. For ordinary cars, this 30 cm height is generally too much.
The object of the present invention is to eliminate the drawbacks mentioned. The articulated jack of the invention is characterized in that the pressure cylinder is placed in the horizontal plane of the frame, the force of the cylinder being applied between one of the end beams of the frame and a connecting beam which connects the movable lower ends of the articulated levers. The invention enables a very low jack construction, even 12 cm, to be achieved because the pressure cylinder can be placed in the horizontal plane and the articulated levers, when in the lowest position, can also be folded down horizontally side by side.
An advantageous embodiment of the invention is characterized in that the body of the pressure cylinder is connected by means of a transverse shaft to lugs attached to the connecting beam and provided with elongated holes, in such manner that the cylinder body, supported by the transverse shaft, moves in the elongated holes while a preliminary lifter placed at the opposite end of the cylinder body lifts the articulated levers from a beam placed between them to a preliminary lifting position before the lifting movement proper begins. In this manner, a sufficient lifting power is achieved for the initial lifting stage when the load rests on the jack.
Another embodiment of the invention is characterized in that the preliminary lifter consists of a lifting lever pivoted on the ends of flat bars attached to the lugs, the preliminary lifting movement of the lifting cylinder being transmitted to said lever. Thus, after the preliminary lifting movement, the preliminary lifter can freely follow the movements of the pressure cylinder and requires no separate actuating means.
A further advantageous embodiment of the invention is characterized in that the movable lower ends of the articulated levers are provided with safety latches movable in the transverse direction and actuated e.g. by pressurized air, the jack being locked in position by the ends of the latch bars engaging lock holes located in the lateral beams of the jack frame.
In the following, the invention is described by the aid of an example, reference being made to the drawing attached, wherein:

Fig. 1 represents the articulated jack in top view.
Fig. 2 represents a lateral view the articulated jack in the high position.
Figs 3,4 and 5 represent different stages of operation of the pressure cylinder.
Fig. 6 represents a section through the jack in fig. 1 along the line VI-VI.
Fig. 7 represents a section fig. 6 along the line VII-VII.
Fig. 8 represents a section fig. 6 along the line VIII-VIII.

The articulated jack consists of a frame 1 placed on a base, e.g. a floor, a lifting table 2 and articulated levers 3,4 located between the frame and the lifting table and movable by means of a pressure cylinder 5. The pressure cylinder is placed in the horizontal plane of the frame, the force of the cylinder being applied between one end beam 6 of the frame and a connecting beam 7 which connects the movable lower ends of the articulated levers 3. The body of the pressure cylinder 5 is connected by means of a transverse shaft 8 to lugs 10 attached to the connecting beam 7 and provided with elongated holes 9, in such manner that, at the beginning of a lifting operation, the cylinder body and the transverse shaft 8 supporting it move as far as permitted by the elongated holes 9 while a preliminary lifter 11 placed at the opposite end of the cylinder body lifts the articulated levers 3,4 from a beam 12 placed between them to a preliminary lifting position before the lifting movement proper begins. The preliminary lifter 11 consists of a lifting lever 14 pivoted on the ends of flat bars 13 attached to the lugs 10, the preliminary lifting movement of the lifting cylinder 5 being transmitted to said lever 14. The movable lower ends of the articulated levers 3 are provided with spring-loaded safety latches 15 movable in the transverse direction and actuated e.g. by pressurized air, the jack being locked in position by the ends of the latch bars engaging lock holes 16 located in the lateral beams of the jack frame. By virtue of the spring 17, the latch bar 15 moves from hole to hole 16 as the jack is performing a lifting movement, and when the jack is being lowered, the latch bar 15 is pushed inwards, i.e. to the open position, by means of pressurized air supplied through the opening indicated by the arrow 18. Experiments have proved that, even using a cylinder as small as 80 mmφ and a pressure of 250 bar, the articulated jack of the invention is capable of lifting loads as heavy as two tons.

Claims

1. Articulated jack consisting of a frame (1) placed on a base, e.g. a floor, a lifting table (2) and articulated levers (3,4) located between the frame and the lifting table and movable by means of a pressure cylinder (5), characterized in that the pressure cylinder (5) is placed in the horizontal plane of the frame, the force of the cylinder being applied between one end beam (6) of the frame and a connecting beam (7) which connects the movable lower ends of the articulated levers (3).

2. Articulated jack according to claim 1, characterized in that the body of the pressure cylinder (5) is supported by a transverse shaft (8) on lugs (10) which are attached to the connecting beam (7) and provided with elongated holes (9), in such manner that, at the initial stage of a lifting operation, the transverse shaft (8) supporting the cylinder body (5) moves in the elongated holes (9), the cylinder body moving along with the shaft, while a preliminary lifter (11) placed at the opposite end of the cylinder body lifts the articulated levers (3,4) from a beam (12) placed between them to a preliminary lifting position before the lifting movement proper begins.

3. Articulated jack according to claim 1, characterized in that the preliminary lifter (11) consists of a lifting lever (14) pivoted on the ends of flat bars (13) attached to the lugs (10), the preliminary lifting movement of the lifting cylinder (5) being transmitted to said lever (14).

4. Articulated jack according to any one of the above claims, characterized in that the movable lower ends of the articulated levers (3) are provided with spring-loaded safety latches (15) movable in the transverse direction and actuated e.g. by pressurized air, the jack being locked in position by the ends of the latch bars engaging lock holes (16) located in the lateral beams of the jack frame.