GB2146065A - Safety gates for safety barriers - Google Patents

Abstract

A safety gate to allow goods through a safety barrier, of the kind wherein a barrier element (22) can be opened in front of the goods and a barrier element (22') consequently closed behind the goods to maintain a safety barrier, is provided with a track in the form of two parallel spaced apart guide tubes (10) each in the form of an inverted U on which each element can rise to open the barrier and descend to close the barrier, a chain running within the guide tubes being adapted to coordinate the movements of the barrier elements such that the rise of either one element coincides with the descent of the other. A motor and limit switches can be used to drive and control the elements. <IMAGE>

Description

SPECIFICATION Safety gates for safety barriers This invention relates to safety gates for safety barriers, and in particular to a safety gate to allow goods through a safety barrier, of the kind wherein a barrier element can be opened in front of the goods and a barrier element consequently closes behind the goods to maintain a continuous safety barrier.

Such safety gates may be used as loading gates at platform edges, or galleries, balconies or ships' sides, and particularly in warehouses having open mezzanine floors with a safety fence or rail along the open edge of the floor. In order to allow goods to be transferred to and from the mezzanine floor, a loading gate is required that will maintain the integrity of the safety barrier while goods are being placed on or removed from the edge of the floor, e.g. by means of a fork lift truck operating from the ground floor of the warehouse. A conventional safety loading gate is constructed as a rigid fence laid out on three sides of a rectangular loading area, pivoted at the free ends of the fence where the fixed safety fence or rail terminates on either side of the gate.Goods, for example on a pallet to facilitate fork lift handling, are placed between the ends of the fixed safety barrier on the open side of the rectangle: the gate is then swung up and over the goods and lowered to the floor on their other side, thereby re-establishing a continuous safety barrier behind the goods.

The disadvantages of such loading gates include their space requirements, according to which room must be provided for the gate to pass in a semicircular arc over the goods. Substantial floorspace and headspace are taken up, which could otherwise be put to more profitable use. The maximum size of article or pallet of goods that can pass through the gate is limited by compromise with the desire to limit the room occupied by the loading gate.

According to the present invention a safety gate of the kind described comprises a first barrier element and a second barrier element each mounted on a track whereon each element can rise to open the barrier and descend to close the barrier and linkage means adapted to co-ordinate the movements of the said elements such that the rise of either one element coincides with the descent of the other.

In this manner the floorspace occupied by the gate need only be marginally greater than that required by the goods, and the height to which the gate opens can be designed without reference to the available floorspace.

Preferably the track extends substantially vertically in the regions thereof where the barrier elements are in their barrier closure position, so that the barrier elements rise substantially vertically in the initial stages of opening the barrier. The two barrier elements may advantageously move spaced apart on a single track, and a particularly preferred track conformation is in the form of an inverted U.

A particularly suitable track comprises a parallel pair of elongate guide members. Each of the pair may then support one end of each barrier element.

Suitable guide members may comprise a channel engaged with the lateral ends of the barrier elements.

Preferred linkage means comprise flexible members constrained to follow the conformation of the track or tracks. Suitably such flexible members are substantially inextensible, so that lowering one barrier element draws the other upwards, and substantially incompressible longitudinally, so that raising one barrier element pushes the other downwards. Examples of such flexible members are a stiff cable and a chain of constant length; they may be constrained to follow the track conformation by being closely confined in a guide tube.

One embodiment of the invention is illustrated by way of example in the accompanying drawings, in which: Figure 1 is a front elevation of a safety loading gate on a platform edge.

Figure 2 is a plan view of the gate; Figure 3 is a side elevation of the gate, showing the platform in section; Figure 4 shows a chain for linking the barrier elements in the gate; and Figure 5 is a detail showing the manner of mounting a barrier element on to the chain, the parts of the track and barrier element being shown in section.

As shown in Figs, 1 to 3, the safety loading gate includes four posts 2, 2 set in a rectangular disposition defining a loading area by the edge of a loading platform 4. The rails 6 of a safety fence along the lip of the platform terminate at each of the two posts 2 on the edge of the platforms. The safety barrier is continued inwards away from the platform edge from each post 2 to the post 2 directly behind it by a pair of horizontal bars 8.

An arched length of conveyor tube 10 substantially in the form of an inverted U is mounted on each pair of posts 2 and 2', one limb of the U being fixed vertically on the post 2 and the other limb being fixed vertically on the post 2'.

Each of the two conveyor tubes 10 contains a length of articulated conveyor chain 12 (Figs, 4 and 5) made up of a plurality of links 14 carrying rollers 16 set alternately at 90 , so that the rollers, which are just smaller than the internal diameter of the tube, keep the chain centred in the tube. The chain in its guide tube is flexible enough to follow the bends in the tube, yet is substantially inextensible and incompressible longitudinally.

As shown in Fig. 5, the tubes 10 are each provided with a continuous longitudinal slot 18 through the tube wall, and cranked barrier element suspension arms 20 which are formed integrally with four of the chain links 14 extend therethrough out of the guide channel constituted by the slotted tube 10.

The safety loading gate is provided with two movable barrier elements 22, 22'. Each comprises a parallel pair of horizontal bars 24, and a teles copic crossmember 26 formed by a short tube 27 welded to one bar 24 fitting loosely inside the open end of a wider short tube 28 welded to the other bar 24.

The two guide tubes 10 are parallel. The chains 12 in each tube are identical and opposite each other so that the four cranked barrier element suspension arms 20 are also set opposite each other.

Each suspension arm carries one lateral end of a barrier element horizontal bar 24 in a rotatable mounting, as shown in Fig. 5, in which a stud 30 extending axially from the bar end is secured rotatably through an aperture in the suspension arm.

The conveyor chains 12 are of a length selected in relation to the lengths of the guide track formed by the parallel conveyor tubes 10 to ensure that when one barrier element is in a lowered position the other is in a raised position. The drawings show the barrier element 22 adjacent the platform edge lowered and the rear barrier element 22' raised; it will be appreciated that in this raised position the telescopic crossmember 26 accommodates the reduced separation of the bars 24 at the arched portions of the guide track. As shown, goods can be transferred freely into and out of the rectangular loading area within the loading gate between the four posts 2 and 2' from the remainder of the platform 4. When the front barrier element 22 is raised to open the barrier at the front of the loading area, and the rear barrier element 22' consequently descends to its barrier closure position, free access to the loading area is now available over the platform edge, while the integrity of the safety barrier overall is maintained by the barrier element 22' and the bars 8 on either side of the loading area.

It will be appreciated that motor means may advantageously be provided to drive the barrier elements between their open and closed positions, and preferably limit switches are also provided to control the motor means and stop the barrier elements automatically when each position is reached.

Claims (11)

1. A safety gate of the kind described comprising a first barrier element and a second barrier element each mounted on a track whereon each element can rise to open the barrier and descend to close the barrier and linkage means adapted to coordinate the movements of the said elements such that the rise of either one element coincides with the descent of the other.

2. A safety gate according to claim 1 wherein the track extends substantially vertically in the regions thereof where the barrier elements are in their barrier closure position.

3. A safety gate according to claim 1 or claim 2 wherein the first and second barrier elements move spaced apart on the same track.

4. A safety gate according to any one of the preceding claims wherein the conformation of the track is in the form of an inverted U.

5. A safety gate according to any one of the preceding claims wherein the track comprises a parallel pair of elongate guide members, each of the pair supporting one end of each barrier element.

6. A safety gate according to claim 5, wherein the guide members comprise a channel engaged with the lateral ends of the barrier elements.

7. A safety gate according to any one of the preceding claims wherein the linkage means comprise flexible members constrained to follow the conformation of the track or tracks.

8. A safety gate according to claim 7, wherein the flexible members are substantially inextensible and substantially incompressible longitudinally.

9. A safety gate according to claim 8, wherein the flexible members comprise chains of constant length closely confined in a guide tube.

10. A safety gate as claimed in any one of the preceding claims in combination with a safety fence, the fence abutting fixed barrier means extending from adjacent the barrier closure position of the first barrier element to adjacent the barrier closure position of the second barrier element.

11. A safety gate substantially as herein described with reference to and as illustrated in the accompanying drawings.