GB1587361A

GB1587361A - Safety device for cable hoisting apparatus

Info

Publication number: GB1587361A
Application number: GB108878A
Authority: GB
Original assignee: FOGAUTOLUBE SA
Current assignee: FOGAUTOLUBE SA
Priority date: 1977-01-11
Filing date: 1978-01-11
Publication date: 1981-04-01
Also published as: BE862172A; IT1089738B; DK143746B; DE2759085A1; DK564477A; DK143746C; FR2376816A1; FR2376816B1

Description

(54) IMPROVED SAFETY DEVICE FOR CABLE HOISTING APPARATUS (71) We, FOGAUTOLUBE S.A., a French Company of 58440 Myennes Sur Loire, France, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to an improved safety device for cable hoisting apparatus and more particularly lifting ramps for motor vehicles.

There are known safety devices which are mounted on lifting ramps comprising a platform intended for supporting a vehicle and guided in two or four columns the said platform being connected to traction or balancing cables. The said safety devices comprise catches or pawls linked to the platform and designed to cooperate with toothed racks on the columns, the said catches being connected to a rocking lever member which, when acted upon by a strong spring, tends to engage the said catches in the racks, the action of the said spring being nullified by a feeler or sensing member which is provided on the rocking lever and cooperates with the cable.

With such devices, as long as the cables are suitably tensioned, the catches are separate from the toothed racks, but as soon as there is a reduction in tension, the rocking lever controls the engagement of the catches in the racks thereby locking the platform.

Such a device operates perfectly and is described particularly in French Patent No.

1 224 112 in the name of the applicant company. However, it has the disadvantage that the catches are not permanently engaged in the racks so that in the event of cable breakage a fall corresponding to the time of engagement of the catches in the racks is recorded.

Hitherto, one had conceived the manufacture of a safety device in which the catch cooperated permanently with the toothed rack during the mounting or lifting of the platform, but moved aside during the descent of the said platform, which had the serious disadvantage of affording no security during descent in the event of cable breakage.

The safety device according to the present invention is applied to cable hoisting apparatus and, more particularly, to lifting ramps comprising a movable platform, vertically supported by cables and guided in columns, the said device comprising catches for cooperating with the racks on the columns and connected kinematically to a rocking lever member which is pivotally mounted on the platform and comprises a feeler or sensing member cooperating with the cable, the said rocking lever member being drawn by a spring which tends to cause it to pivot in opposition to the force of the tensioned cable, in order to control engagement of the catches in the racks in the event of abnormal reduction in tension or breakage of the cable, the safety device being characterized in that the catch is connected to the rocking lever, in the position in which the latter is maintained by the tensioned cable, by means permitting free movement of the said catch from one position engaged in the rack to a position aside therefrom, resilient means being provided to tend to engage the said catch in the rack, and the said catch being connected by a transmission to a member for controlling the movement aside from the rack, the said transmission comprising a part of variable length which is maintained in one predetermined position by means capable of yielding to more than a predetermined effort. Owing to this arrangement, the catch is maintained in contact with the rack during the ascent of the platform offering a high degree of safety.

whereas during the descent of the said platform it is disengaged from the said rack by the control member, but can nevertheless be pulled by the rocking lever in the event of breakage or reduction in tension of the cable, owing to a modification of the length of the part with variable length in the transmission in opposition to the means which it comprises.

In accordance with another feature the catch comprises a ball penetrated diametrically by a first conduit through which extends a connecting rod taking its bearing at one end on the rocking lever and the other end of which comprises a stop cooperating with the ball, the latter comprising a second diametral tube through which extends a connecting rod, one end of which is connected to a balancer linked to the platform, whereas the other end comprises a stop cooperating with the ball, a spring tending to urge the catch towards a position in which it cooperates with the toothed rack and in which the aforementioned final stop bears against the said ball, the balancer being connected by a telescopic shaft to an angle iron linked to the platform and connected to a control member, the said telescopic shaft being maintained in a predetermined position by resilient means.

In accordance with another feature of the invention resetting means act upon the angle iron to keep it pressed against a stop in an angular position in which the catch is in contact with the rack.

The angle iron control means preferably comprises a cable fixed at one end thereto passing over two pulleys, one situated at the top of the column and the other at the bottom, the other end of which being fixed to the platform, and further comprises a lever pivotally linked to the column and comprising a support which is intersecting the cable and on which two loose pulleys are mounted for cooperation with the cable.

Finally, the balancer is connected by a kinematic transmission to catches cooperating with toothed racks on the other columns.

The invention will now be described in more detail with reference to a special embodiment presented only by way of example and shown in the accompanying drawings.

In these drawings: Fig. 1 is a diagrammatic view in perspective showing a lifting ramp for motor vehicles, Fig. 2 is a schematic view in simplified perspective showing one of the columns of the lifting ramp as well as the entire safety device, Fig. 3 is a schematic view showing the safety device with the lifting ramp in the descent position, Fig. 4 is a schematic view showing the operation of the safety device, after breakage of the cable supporting the ramp.

The lifting ramp shown in Figure 1 comprises a platform 1 supported by four cables 2, each set in a tubular column 3 in which the said platform 1 is guided.

The cables 2 are connected to an apparatus (not shown) for raising and lowering the platfonn 1 at will.

Each column 3 comprises a vertical slot 4 which is penetrated by one end 5 of a cross member 6 of the platform 1.

Each column 3 is provided with a series of perforations 7 which form a rack parallel to the slot 4.

As shown in Figures 2 to 4, a rocking lever member 8 is mounted on the end 5 of the cross member 6. The member 8 comprises a yoke or shell through which the cable 2 passes and which is pivoted about an axle 9, the said yoke or shell comprising a pulley 10 which is pressed against the cable 2 under the force of a spring-loaded jack 11 interposed between the said rocking lever member 8 and a fixed point on the cross member 6.

The spring-loaded jack 11 tends to cause the lever to rock about the axle 9 but the pulley 10, by cooperating with the cable which is tensioned, resists this rocking action.

A catch or pawl 12 is pivoted on the end 5 of the cross member 6 about an axle 13 and connected to the rocking lever 8 by a link 14 one end of which is linked to the said rocking lever about an axle 15 (see Figure 2), while the other end extends freely through a diametral hole in a ball 16 pivoted on the catch 12, the free end of the said link comprising a stop 17 for bearing against the ball 16.

The catch 12 comprises a tooth for cooperating with the rack of the column 3.

The catch 12 is connected to a catch 12a for cooperating with the rack of the column 3 into the slot of which the other end of the cross member 6 is inserted by a connecting rod 20, a balancer 21 being pivoted at 22 on the cross member 6, a connecting rod 23, a bellcrank lever 24 and a connecting rod 25.

Catches 12b and 12c are intended for cooperation with the racks of the two other columns and are interconnected by a kinematic transmission identical to that which has just been described and composed of a connecting rod 20a, a balancer 21a, a connecting rod 23a, a bell-crank lever 24a and a connecting rod 25a, the balancers 21 and 21a being rigidly connected by a coupling bar or tie rod 26.

Therefore, all the pivoting action of one catch 12 involves a movement of the same amplitude by all the other catches.

At an intermediate point along its length, the connecting rod 20 has a stop 50 against which bears a spring 51 the other end of which cooperates with the ball 16, the said connecting rod 20 passing diametrically and freely through the latter.

The connecting rods 20a, 25 and 25a respectively slide freely in balls 47 provided on the corresponding catches and a spring 51 is interposed between the balls 47 and stops 50 provided on the respective rods.

Pivotably mounted on the end 5, on an axle 55, is an angle iron 56 to which is attached one end of a control cable 52 guided over pulleys 53 and 54 of the column 3, the other end of the said cable being secured to the said end 5.

Mounted on the said column is a lever 45 which is pivotally mounted on an axle 46 and supports two pulleys 49 intended for cooperating with the cable 52.

The angle iron 56 is connected to the balancer 21 by a telescopic shaft 33 comprising a female component 34 and a male com ponent 35, the said components comprising respectively stops 36 and 37 between which a compression spring 38 is interposed.

On the end 5 there is provided a stop 39 against which the angle iron 56 is normally retained by a spring 40 interposed between a stop 41 and a shoulder 43 of a guide shaft 42 linked to the angle iron 56.

It should be noted that the spring 38 is stronger than the spring 51 and that the spring 40 is stronger than the spring 38 since it is intended to serve as a means of resetting the entire arrangement.

The safety device operates as follows: During the ascent of the platform, the catches occupy the position shown in Figure 2; propelled by the springs 51, they tend to cooperate with the racks 7 and are moved aside resiliently whenever they pass between two apertures in the rack. This arrangement affords a high degree of safety since the catches 12 are therefore always engaged.

To allow the platform 1 to be moved downwardly, the lever 45 is applied in the direction of the arrow in Figure 2 so that the pulleys may bear against the cable 52 and a tractive force may be exerted on the said cable which thus controls the pivoting or rocking of the angle iron 56 about its axle 55 in opposition to the action of the spring 40, the effect of which is to cause displacement, in the direction of the arrow f (Fig. 3) of the shaft 33 which therefore controls the pivoting action of the balancer 21 in order that the link 20 may be moved downwards, exerting a tractive effort or pull on the catch 12 which is then disengaged from the rack (Fig. 3).

The effort to be produced by the shaft 33 is weak and the compression spring 38 is not observed during this action.

As the balancer 21 controls the other catches 12a, 1 2b and 12c, the latter are at the same time moved clear of the corresponding racks.

The movement of the catches 12 has no influence on the rocking lever 8 since the link 14 can slide freely in the ball 16.

If during the descent of the platform a reduction in the tension or a breakage of the cable 2 is observed under the effect of the spring-loaded jack 11, the rocking lever will pivot and the link 14, by cooperating with the ball 16, will drive the catch 12 towards the locking position (Fig. 4).

During this movement the connecting rod 20 drawn by the ball 16 will move the balancer 21 towards the locking position of the catches 12, which is possible on account of the telescopic assembly of the shaft 33. As the springloaded jack 11 is much stronger than the spring 38, the balancer 21 pivots while driving back the female component 34 in opposition to the action of the spring 38.

With the catches in this position, the platform 1 is immobilised and can no longer be moved.

It can be understood that the device according to the invention affords a high degree of safety, firstly, because with the lifting ramp in an ascending position the catches 12 are in an operative position, i.e.

during ascent they co-operate with the racks, and, secondly, because in the descending position, with the catches disengaged, the safety device remains ready to operate as soon as the tension of the cable 2 diminishes.

The invention is obviously not limited to the embodiment just described and illustrated; it will be possible to effect numerous modifications of details without departing from the scope of the invention as defined in the appended claims. For example, it would be possible to replace the spring 38 of the variable length linkage 34, 35 with a device comprising means for locking the components 34 and 35 relative to one another, the said means yielding when an effort exceeds a predetermined value, that is to say, when the catch 12 is pulled by the springloaded jack 11, as a result of breakage of the cable 2.

WHAT WE CLAIM IS: 1. An improved safety device for cable hoisting apparatus, particularly apparatus such as lifting ramps for vehicles comprising a movable platform vertically supported by cables and guided in columns, the said device comprising catches intended for cooperating with racks on the columns and connected kinematically to a rocking lever member pivotally mounted on the platform and comprising a feeler member cooperating with the cable, the said rocking lever member being pulled by a spring which tends to cause the said lever to rock or pivot in opposition to the tensioned cable in order to control engagement of the catches in the racks in the event of breakage or abnormal reduction in tension of the said cable, characterised in that the catch is connected to the rocking lever, in the position in which the latter is maintained by the tensioned cable, by means permitting free movement of the said catch from one position engaged in the rack, to a position moved aside therefrom, resilient means being provided to tend to engage the said catch in the rack, and the said catch being connected by a transmission to a member for controlling the movement aside from the rack, the said transmission comprising a component of variable length maintained in a predetermined position by means capable of yielding when a predetermined effort is exceeded.

2. A safety device for cable hoisting apparatus as claimed in Claim 1, characterised in that the catch comprises a ball penetrated diametrically by a first tube through which extends a connecting rod linked by one

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. ponent 35, the said components comprising respectively stops 36 and 37 between which a compression spring 38 is interposed. On the end 5 there is provided a stop 39 against which the angle iron 56 is normally retained by a spring 40 interposed between a stop 41 and a shoulder 43 of a guide shaft 42 linked to the angle iron 56. It should be noted that the spring 38 is stronger than the spring 51 and that the spring 40 is stronger than the spring 38 since it is intended to serve as a means of resetting the entire arrangement. The safety device operates as follows: During the ascent of the platform, the catches occupy the position shown in Figure 2; propelled by the springs 51, they tend to cooperate with the racks 7 and are moved aside resiliently whenever they pass between two apertures in the rack. This arrangement affords a high degree of safety since the catches 12 are therefore always engaged. To allow the platform 1 to be moved downwardly, the lever 45 is applied in the direction of the arrow in Figure 2 so that the pulleys may bear against the cable 52 and a tractive force may be exerted on the said cable which thus controls the pivoting or rocking of the angle iron 56 about its axle 55 in opposition to the action of the spring 40, the effect of which is to cause displacement, in the direction of the arrow f (Fig. 3) of the shaft 33 which therefore controls the pivoting action of the balancer 21 in order that the link 20 may be moved downwards, exerting a tractive effort or pull on the catch 12 which is then disengaged from the rack (Fig. 3). The effort to be produced by the shaft 33 is weak and the compression spring 38 is not observed during this action. As the balancer 21 controls the other catches 12a, 1 2b and 12c, the latter are at the same time moved clear of the corresponding racks. The movement of the catches 12 has no influence on the rocking lever 8 since the link 14 can slide freely in the ball 16. If during the descent of the platform a reduction in the tension or a breakage of the cable 2 is observed under the effect of the spring-loaded jack 11, the rocking lever will pivot and the link 14, by cooperating with the ball 16, will drive the catch 12 towards the locking position (Fig. 4). During this movement the connecting rod 20 drawn by the ball 16 will move the balancer 21 towards the locking position of the catches 12, which is possible on account of the telescopic assembly of the shaft 33. As the springloaded jack 11 is much stronger than the spring 38, the balancer 21 pivots while driving back the female component 34 in opposition to the action of the spring 38. With the catches in this position, the platform 1 is immobilised and can no longer be moved. It can be understood that the device according to the invention affords a high degree of safety, firstly, because with the lifting ramp in an ascending position the catches 12 are in an operative position, i.e. during ascent they co-operate with the racks, and, secondly, because in the descending position, with the catches disengaged, the safety device remains ready to operate as soon as the tension of the cable 2 diminishes. The invention is obviously not limited to the embodiment just described and illustrated; it will be possible to effect numerous modifications of details without departing from the scope of the invention as defined in the appended claims. For example, it would be possible to replace the spring 38 of the variable length linkage 34, 35 with a device comprising means for locking the components 34 and 35 relative to one another, the said means yielding when an effort exceeds a predetermined value, that is to say, when the catch 12 is pulled by the springloaded jack 11, as a result of breakage of the cable 2. WHAT WE CLAIM IS:

1. An improved safety device for cable hoisting apparatus, particularly apparatus such as lifting ramps for vehicles comprising a movable platform vertically supported by cables and guided in columns, the said device comprising catches intended for cooperating with racks on the columns and connected kinematically to a rocking lever member pivotally mounted on the platform and comprising a feeler member cooperating with the cable, the said rocking lever member being pulled by a spring which tends to cause the said lever to rock or pivot in opposition to the tensioned cable in order to control engagement of the catches in the racks in the event of breakage or abnormal reduction in tension of the said cable, characterised in that the catch is connected to the rocking lever, in the position in which the latter is maintained by the tensioned cable, by means permitting free movement of the said catch from one position engaged in the rack, to a position moved aside therefrom, resilient means being provided to tend to engage the said catch in the rack, and the said catch being connected by a transmission to a member for controlling the movement aside from the rack, the said transmission comprising a component of variable length maintained in a predetermined position by means capable of yielding when a predetermined effort is exceeded.

end to the rocking lever, the other end of which comprising a stop cooperating with the ball, the latter comprising a second diametrical tube penetrated by a connecting rod, one end of which is connected to a balancer linked to the platform, while the other end comprises a stop cooperating with the ball, a spring tending to urge the catch towards a position in which it cooperates with the rack and in which the aforementioned last stop bears against the said ball, the balancer being connected by a telescopic shaft to one side of an angle iron which is linked to the platform and connected to a control member, the said telescopic shaft being maintained in a predetermined position by resilient means.

3. A safety device for cable hoisting apparatus as claimed in Claims 1 and 2, characterised in that resetting means act upon the angle iron in order to keep it pressed against a stop in an angular position in which the catch is in contact with the rack.

4. A safety device for cable hoisting apparatus as claimed in Claims 1, 2 and 3, characterised in that the angle iron control means comprises a cable fixed by one end to the angle iron, passing over two pulleys, one situated at the bottom of the column and the other at the top, the other end of said cable being attached to the platform, and further comprises a lever pivotally connected to the column and comprising a support which intersects with the cable and on which are mounted two loose pulleys intended for cooperation with the cable.

5. A safety device for cable hoisting apparatus as claimed in Claims 1, 2, 3 and 4, characterised in that the balancer is connected by a kinematic transmission to catches cooperating with racks on the other columns.

6. A safety device for cable hoisting apparatus substantially as herein described with reference to and as illustrated in the accompanying drawings.