WO2007088145A1

WO2007088145A1 - Improved pantograph lift

Info

Publication number: WO2007088145A1
Application number: PCT/EP2007/050817
Authority: WO
Inventors: Eride Rossato; Alberto Comand
Original assignee: O.Me.R. S.P.A.
Priority date: 2006-02-02
Filing date: 2007-01-29
Publication date: 2007-08-09
Also published as: ITVE20060005A1

Abstract

Pantograph lift, comprising a floor resting base (2) , a platform (4) for the load to be lifted, at least two pairs of main arms (6, 6') interposed between said base (2) and said platform (4) and pivoted together at their central point (8) , and actuator members (20) wherein both the ends (10) of each main arm (6, S') are articulatedly slidable along said base (2) and along said platform (4) , - at least one of the two main arms (6, 6' ) of each pair is connected to the central point (14, 16) of the corresponding base (2) and of the corresponding platform (4) by a secondary arm (12, 12' ) which has a length equal to one quarter of the length of the main arm (6, 6') and is connected at one end to said central point (14, 16) and at its other end to the central point (18, 18' ) of one of the two half-arms into which said main arm (6, 6' ) is divided by the point (8) at which it is pivoted to the other main arm.

Description

IMPROVED PANTOGRAPH LIFT

The present invention relates to an improved pantograph lift, particularly for motor vehicles.

Pantograph lifts are known for lifting heavy loads, which often consist of motor vehicles but could equally consist of loads of other types.

These known pantograph lifts generally comprise a pair of base longitudinal members to rest on or be fixed to the floor, a pair of raisable runways on which the motor vehicle to be lifted is positioned, a complex of arms centrally pivoted together and hinged at their ends to said base longitudinal members and to said runways, and a series of actuators which act in the sense of varying the contained angle between the pivoted arms to cause the runways to rise and descend.

In known pantograph lifts the base longitudinal members can be replaced by a single platform resting on or fixed to the floor, the two raisable runways also being able to be replaced by a single platform on which the load to be lifted is positioned.

Independently of the specific configuration, the assembly of pivoted arms generally comprises two pairs of arms, in each pair one arm being simply hinged at its lower end to a corresponding longitudinal member and being slidably hinged at its other end to the overlying runway, the other arm being simply hinged at its upper end to the runway and being slidably hinged at its lower end to the underlying longitudinal member. This is because during lifting, the variation in the angle between the two arms of each pair results in a reduction in the distance between their corresponding ends, hence requiring that one of the two ends be hinged to a pin slidable along the runway or along the longitudinal member, in order to allow the distance from the end of the other arm to vary, this being instead hinged to a fixed pin.

This known type of lift presents the drawback that the resting base, defined by the hinging points between the arms and runways, not only inevitably decreases during lifting because of the approach between the ends of the arms of each pair, but decreases in a non-centred manner, in that one point remains at rest while the other moves. It follows that a load which has been correctly positioned on the runways and is perfectly balanced when the lift is lowered, becomes increasingly unbalanced as the lift rises. Figures 1 and 2 show a traditional pantograph lift in the lift-lowered and lift-raised condition. It will be noted that when the lift is lowered the vehicle forms a balanced load if correctly positioned on the runways, whereas when the lift is raised the vehicle forms an unbalanced load in the sense of being off-centered. This drawback results in strong limitations on the use of the lift, in the sense that it limits the maximum attainable height to values compatible with an acceptable load unbalance and always seriously stresses the lift.

This drawback is eliminated according to the present invention by an improved pantograph lift as described in claim 1. A preferred embodiment of the present invention is described in detail hereinafter with reference to the accompanying drawings, in which: Figure 1 is a schematic side view of a pantograph lift of the traditional art in its lowered condition, Figure 2 shows it in the same view as Figure 1 but in its raised condition, Figure 3 is a schematic side view of a pantograph lift according to the invention in its lowered condition, Figure 4 shows it in the same view as Figure 3 but in its raised condition.

As can be seen from the figures, the lift of the invention comprises a pair of longitudinal members 2 fixed to the floor, a pair of runways 4 on which the load to be lifted in positioned, and two pairs of main arms 6, 6' pivoted together at their central point 8 and provided at their ends with rollers 10 or bearings or any other member which enables the arm 6, 6' to slide articulatedly along the respective longitudinal member 2 or along the respective runway 4.

According to the invention, one of the two main arms 6 of each pair is further connected to the respective runway 4 while the other main arm 6' is further connected to the respective longitudinal member 2, these further connections being made by secondary arms 12, 12' which have a length between their pivotal axes of one quarter of the length of the main arms 6, 6' and are pivoted at one end to the central point 14 of the runway 4 or to the central point 16 of the longitudinal member 2, and at their other end to the intermediate point 18, 18' between the end of the main arm and the pivotal point 8 between the two main arms 6, 6'.

The lift of the invention is also provided with suitable lifting means, which in the illustrated example consist of a pair of hydraulic cylinder-piston units 20, interposed between the two main arms 6, 6' and arranged to modify, by varying their length, the angle between the arms, to hence raise and lower the lift.

From simple geometrical considerations it is apparent that although the lift load base, which is defined lowerly by the distance between the two lower ends of the two main arms 6, 6', i.e. between the lower rollers 10, and upperly by the distance between the two upper ends thereof, i.e. between the upper rollers 10, decreases as the lift is raised, it always remains centered about the central point 14 of the runways 4 and about the central point 16 of the longitudinal members 2, and about the pivotal point 8 of the two pairs of main arms 6, 6'. Consequently, if the load has been positioned in a balanced condition on the runways 4, the same balanced condition remains while the lift is raised, hence enabling greater heights to be attained than those attainable with traditional lifts for equal lift dimensions, and always operating under balanced load conditions.

The aforedescribed lift also comprises all those members normally provided in any lift, i.e. connections between the cylinder-piston units 20 and a hydraulic fluid pumping station, safety devices to prevent the lift from falling in the case of accidental breakage of the connections to the cylinder-piston units 20, safety valves within the feed circuit to the cylinder-piston units 20, safety devices to prevent damage in the case of operational errors, etc. As all these members are of traditional type and do not modify the general principle on which the present invention is based, they have been omitted to prevent unnecessary amplification of the present description.

Claims

C L A I M S

1. An improved pantograph lift, comprising a floor resting base (2), a platform (4) for the load to be lifted, at least two pairs of main arms (6, 6') interposed between said base (2) and said platform (4) and pivoted together at their central point (8), and actuator members (20) able to modify the angle formed between the two main arms (6, 6') of each pair, characterised in that:

- both the ends (10) of each main arm (6, 6') are articulatedly slidable along said base (2) and along said platform (4),

- at least one of the two main arms (6, 6') of each pair is connected to the central point (14, 16) of the corresponding base (2) and of the corresponding platform (4) by a secondary arm (12, 12') which has a length equal to one quarter of the length of the main arm (6, 6') and is connected at one end to said central point (124, 16) and at its other end to the central point (18, 18') of one of the two half-arms into which said main arm (6, 6') is divided by the point (8) at which it is pivoted to the other main arm.

2. A lift as claimed in claim 1 , characterised in that a main arm (6) of each pair of arms (6, 6') is connected by a secondary arm (12) to the platform (4), the other main arm (6') of the same pair of main arms (6, 6') being connected by another secondary arm (12) to the base (2).

3. A lift as claimed in claim 1 , characterised in that the base (2) consists of a pair of longitudinal members.

4. A lift as claimed in claim 1 , characterised in that the platform (4) consists of a pair of runways.

5. A lift as claimed in claim 1 , characterised in that two hydraulic cylinder- piston units (20) are interposed between the two main arms (6, 6') of each pair.