GB2101961A

GB2101961A - Vertically movable and tiltable vehicle lifting fame

Info

Publication number: GB2101961A
Application number: GB08213435A
Authority: GB
Inventors: Arne Henriksson
Original assignee: KALMAR LAGAB AB
Current assignee: KALMAR LAGAB AB
Priority date: 1981-05-12
Filing date: 1982-05-10
Publication date: 1983-01-26
Also published as: GB2101961B; DK210082A; SE426376B; NO821564L; SE8102965L

Abstract

A mechanism in lorries of the kind which are equipped with a lifting frame (5) which is mounted on the chassis (1) to support a removable load carrier (6). A tilting cylinder (10) is arranged to raise, lower and to tilt the lifting frame (5), said frame provided with at least one pair of forwards and rear link arms (2, 4). To control the tilting movement, the mechanism is provided with means to disengage the pivot connection (15) between the lifting frame (5) and the forwards (upper) ends of the front pair of link arms (2). The lower ends of the rear pair of support arms (21) are articulated to the chassis (1) behind and adjacent the chassis wheel axle and a tilting strut (24) extends essentially rectilinearly from a forwards pivot point (25) on the chassis (1) to a pivot point (20), in the lowered position of the frame 5. The tilting strut (24) is equipped with both a toggle joint (26) and means (28) in which engage locking means on the lifting frame (5) prior to initiation of a tilting movement. <IMAGE>

Description

SPECIFICATION An arrangement in lorries equipped with a vertically movable and tiltable lifting frame The subject invention concerns an arrangement in lorries of the kind which are equipped with a lifing frame which is mounted on the lorry chassis to support a removable load carrier, such as a loading platform, and which is arranged to be raised and lowered as well as tilted with the aid of a frame-tilting cylinder unit.The lifting-frame movement system also includes two pairs of link arms, one front and one rear pair, means to disengage the pivot connection between the lifting frame and the forwards (upper) end of the front pair of link arms, a pair of support arms to the upper ends of which are pivotally connected the rear (lower) ends of said rear pair of link arms, the lower ends of said support arms being pivotally mounted on the chassis at a point behind and adjacent the rear wheei axle of the chassis, and a tilting strut the front end of which is articulated to the chassis.

An arrangement in lorry lifting platforms of this kind is known from SE Published Specification 7907614-7. With the aid of the lifting-frame tilting mechanism disclosed therein the tilting movements of the lifting frame are guided in such a manner that the platform is moved somewhat forwards and upwards during the tilting movement. This displaces the centre of gravity of the platform forwards, which reduces the risk that the lorry tips over backwards. This risk is otherwise present when the load is wet soil, clay or the like which may stick to the bottom of the loadreceiving surface of the platform. In addition, this forwards-upwards movement diminishes the risk that the rear flap of the platform will be squeezed against the ground towards the end of the tilting or dumping movement.

The tilting mechanism just described includes means to secure or immobilize the rear pivot points on the lifing arms, one on either side of the chassis. These two means, which are necessary to control the lifting movement which must be performed in order that it be possible to deposit the platform on the ground, must be disengaged before the tilting or dumping movement can be initiated. In addition, the lorry must be equipped with means designed to lock the forwards end of the tilting strut against lengthwise movements before the dumping movement is started, while allowing it to pivot about its pivot point in the chassis.

Should any one of these means for any reason malfunction or fail, there is a risk that damage may be done to the lifting frame including its strut and articulation joints in case of lifting and/or dumping movements.

The lifting-frame tilting mechanism in accordance with the subject invention is designed to ensure vertical movements as well as tilting movements in the same way as in the case of the lifting frame disclosed in the above SE Published Specification 7907614-7. The purpose of the invention is to realize these movements with simpler means and without having to include means to secure and to disengage the forwards end of the tilting strut or the rear pivot joints of the lifting arms.

The invention is characterised in that when the lifting frame rests on the chassis, the tilting strut extends essentially rectilinearly from a forwards pivot point on the chassis to the pivot point which is common to the support arms and the rear pair of link arms, the tilting strut being equipped with both a toggle joint and, at the rear part of the tilting strut, with means in which engage locking means on the lifting frame prior to initiation of a tilting movement.

The tilting frame mechanism in accordance with the invention will be explained in closer detail in the following with reference to one embodiment thereof as shown in the accompanying drawings, wherein Figure 1 is a lateral view of a lorry equipped with a lifting frame in accordance with the invention, the lifting frame being shown in its lower position, Figure 2 is a plan view of the lifting frame, parts of the chassis and the strut connections thereof, Figure 3 illustrates parts of the details of Fig. 2 on an enlarged scale with some parts shown in broken views, and Figures 4 and 5 are lateral views of the lorry, Fig. 4 showing the lifting frame in the upper position thereof and Fig. 5 showing the lifting frame in the dumping position.

The chassis 1 of the lorry illustrated in the drawings is equipped with a mechanism designed to impart parallel motions to a lifting frame 5 and including three pairs of link arms 2, 3, and 4 which are pivotally connected to the lifting frame 5. The lifting frame 5 supports a load carrier 6. The latter is arranged, when the lifting frame has been raised, to be deposited on ground 8 on retractable and/or foldable legs 7. In its lower position, the lifting frame 5 may be secured to the chassis 1 by means of locking means 9.

The lorry includes a hydraulic piston-andcylinder unit 10 serving to tilt the lifting frame.

The cylinder unit is connected to the pressurized-oil system (not shown) of the lorry and is pivotally mounted on the chassis 1 about a shaft 11. The piston 1 2 of the cylinder unit is pivotally mounted on the lifting frame 5 by means of a pivot pin 1 3.

The rear (lower) ends of the forwards pair of link arms 2 are articulated to the chassis 1 in pivot points 1 4 and locking means (not shown) are arranged to releasably connect their forwards (upper) ends to the lifting frame 5 in pivot points 15.

The lower (rear) ends of the centre pair of link arms 3 are connected to the chassis by means of an articulation joint 1 6. The front (upper) ends are via locking means (not shown) releasably connected with the lifting frame 5 in pivot points 1 7 in the same way as the front pair of link arms The pivot point 1 7 of the front (upper) ends also forms a means for mounting the forwards end of a stabilizing arm 18, the rear end of which is articulated at pivot point 1 9 to the lifting frame 5, said arm together with the centre pair of link arms forming a dumping movement stabilizing means.

The rear (lower) ends of the rear pair of link arms 4 are by means of a transverse tilting shaft 20 articulated to the upper ends of a pair of support arms 21. The lower ends of the support arms are pivotally mounted about their respective one of transverse pivot pins 22 which are arranged on support plates 23, one on either side of the chassis 1. The front (upper) ends of the link arms 4 are connected to the lifting frame 5 in pivot points 4' The rear end of a tilting strut 24 is articulated to the shaft 20 on either side of the chassis 1 as are also the rear link arms 4 and the support arms 21. The tilting strut 24 extends in parallel with and along the chassis 1 to an articulation point 25 therein. In addition, the tilting strut is provided with a toggle joint 26 which is positioned at some distance from the tilting shaft 20.Furthermore, the rear portion 24' of the tilting strut (i.e. the portion intermediate the toggle joint 26 and the tilting shaft 20) is releasably connected to the lifting frame 5 via transverse and lengthwise struts 24". Locking means 27 on the lifting frame 5 are arranged to engage in lifting loops 28 formed on the lengthwise struts 24" (see Fig. 3).

When the load carrier 6 is transported on the lorry with the lifting frame 5 in the lower position (Fig. 1) and the legs 7 in their retracted or upper position and is to be deposited on ground 8, the lifting frame 5 is lifted by the tilting cylinder unit 10 after disengagement of the lifting frame 5 from the chassis 1 and the lifting loops 28 on the tilting strut 24. While the frame is lifted to the position illustrated in Fig. 4, the tilting strut 24 rests rectilinearly on the chassis 1 between the pivot point 25 and the tilting shaft 20. In case the loading platform 6 is so loaded that the centre of gravity will be positioned at a point adjacent the front of the platform 6 the tilting strut 24 will prevent the tilting shaft 20 together with the support arms 21 from moving forwards and upwards.Such a forwardsupwards movement could cause damage to the mechanism. When the loading platform 6 is in the raised position the legs 7 are lowered into contact with the ground 8. The lifting frame 5 is disconnected from the platform 6, whereupon the lifting frame is lowered to its lower position (Fig. 1) and the lorry may be driven away. clear of the platform that remains standing on the ground, supported by the legs 7.

When the platform 6 is to be tilted to the dumping position, the lifting frame 5 is disconnected from the chassis 1 and the forward and centre link arm pairs 2 and 3 are disconnected from the lifting frame 5. The lifting loops 28 on the rear portion 24' of the tilting strut 24 are secured to the lifting frame 5 by means of the locking means 27. The frame is elevated by means of the tilting cylinder unit 19, the forwards link arm pair 2 remaining idle on the chassis 1. Together with the stabilizing arm 1 8 the two central link arms 3 form a dumping position stabilizing means.

The forwards portions of the tilting strut 24 are connected via the toggle joints 26 to the rear portions 24', the latter being rigidly connected with the lifting frame 5 via the locking loops 28. The forwards portions of the tilting strut 24 thus will guide the platform 6 forwards during the dumping movement. The connection between the tilting strut 24 and the chassis 1 via the support arms 21 will guide the rear edge of the platform 6 forwards essentially in parallel with the ground.

Valves and lines incorporated in the hydraulic system of the lorry have been eliminated from the drawings in order not to unnecessarily clutter the latter. For the same reason the electrical means serving to control the valves from the lorry driver's cabin or from a portable control box are not either illustrated in the drawings. The electrical equipment should be such as to ensure that it cannot by mistake disengage other locking means than those required to permit the dumping movement and the raising and lowering movements of the lifting frame.

A number of modifications are possible within the scope of the appended claims.

Other locking and disengagement means than those described above and illustrated in the drawings are possible.

Claims

A mechanism in lorries of the kind comprising a lifting frame which is positioned on the lorry chassis (1) to support a removable load carrier (6), such as a loading platform, said lifting frame (5) arranged to be raised and lowered as well as to be tilted and provided with at least one pair of forwards link arms (2) and one pair of rear link arms (4) arranged between said lifting frame (5) and said chassis (1) to control the raising and lowering movements, and with means for disengaging the pivot connection (15) between the lifting frame (5) and the forwards (upper) end of the forwards pair of link arms (2) in order to control the tilting movement, a pair of support arms (21) the lower ends of which are pivotally mounted on said chassis (1) at a point behind and adjacent the rear wheel axis thereof, the upper ends of said support arms being pivotally connected at a pivot point (20) with the rear (lower) ends of the rear pair of link arms (4), and a tilting strut (24), characterised in that when the lifting frame (5) rests on the chassis (1) the tilting strut (24) extends essentially rectilinearly from a forwards pivot point (25) on the chassis (1) to the pivot point (20) which is common to said support arms (21) and the rear pair of link arms (4), the tilting strut (24) being equipped with both a toggle joint (26), and, at the rear part (24') of the tilting strut (24), with means (28) in which engage locking means (27) on the lifting frame (5) prior to initiation of a tilting movement.
2. A lifting frame mechanism for lorries, substantially as hereinbefore described with reference to the accompanying drawings.