GB2064462A - Conveying apparatus - Google Patents

Abstract

A conveying apparatus, e.g. a builders hoist, comprises conveying means selectively movable in first and second opposed directions, drive means allowing movement of said conveying means and gear means 8 operatively associated with said drive means. The gear means 8 has first and second positions for respectively controlling movement of said conveying means in the first and second directions and a neutral position at which said conveying means is stationary. Means 3, 4, 5, 6 are provided for moving the gear means to the neutral position when the conveying means has moved a predetermined distance in said first or second directions, so that the motion of the conveying means is arrested. <IMAGE>

Description

SPECIFICATION Conveying apparatus The present invention relates to conveying apparatus.

According to the present invention there is provided conveying apparatus comprising conveying means selectively movable in first and second opposed directions, drive means allowing movement of said conveying means, gear means operatively associated with said drive means, which gear means has first and second positions for respectively controlling movement of said conveying means in the first and second directions and a neutral position at which said conveying means is stationary, and means for moving the gear means to the neutral position when said conveying means has moved a predetermined distance in said first or second directions.

The preferred embodiment of conveying apparatus is intended as a hoist for building work for raising building materials from ground level to an upper storey or roof of a building. Preferably the conveying means of such a hoist is a carriage movable along an elongate track structure which in use of the apparatus will be inclined upwardly to allow said carriage to convey materials to the upper part of a building.

Preferably such a hoist will include, at that end of the track, which will be the lower end in use, a winch drum which will be rotated by a drive means which is coupled to the drum through a gear box having a selector lever having three positions, namely a position for clockwise rotation of the drum, one for anti-clockwise rotation, and an intermediate neutral position at which the drum will be stationary. A winch cable will be wound around the drum and will pass around an idle pulley at the opposite end of the track to the drum before being attached to the carriage.

Consequently rotation of the drum to take up the winch cable will cause the carriage to travel up the inclined track, whereas rotation of the drum in the opposite direction allows the carriage to make a controlled descent down the track.

The hoist will also include means for ensuring that once the carriage has reached pre-determined upper or lower positions rotation of the drum will be stopped so that the carriage is arrested.

One such means may comprise a rotary plate provided adjacent the selector lever and having a plurality of apertures arranged on a circular locus.

The rotary plate will be driven by the winch drum through a reduction gear, e.g. a worm and wheel reduction gear, so that the plate is rotated through a known angle for any given number of revolutions of the winch drum which of course corresponds to a certain movement of the carriage.

The apertures in the rotary plate are adapted to accommodate pegs or the like which may act against the selector lever. Two pegs will be used and will be positioned as follows. Firstly, with the carriage in the lowermost desired position and with the selector lever in neutral, a first peg will be located in an aperture which prevents movement of the selector lever to the position which would give further downward travel of the carriage.

Similarly, with the carriage in the uppermost desired position, and with the selector lever in neutral, a second peg is positioned in an aperture which prevents movement of the selector lever to the position causing further upward movement of the carriage. Consequently, when the carriage is in the upper position, the selector lever can only be moved to the position at which the winch drum produced downward movement of the carriage.

The carriage will move downwards until the rotary plate has revolved sufficiently for the first peg to engage the selector lever and urge this lever to the neutral position, thus arresting the carriage at the desired lower position. The selector lever may then be moved to the position allowing upward movement of the carriage, such movement being continued until the second peg urges the selector lever back to the neutral position. It will thus be seen that the carriage can only work between two limit positions, such positions being determined by the angular spacing of the first and second pegs.

Instead of a rotary plate as described above, it is also possible to use a rotary lead screw driven by the winch drum and'having two adjustable stops, which function in the same manner as the first and second pegs described above, to allow the upper and lower extremes of travel of the carriage to be set. One example of such an arrangement is shown in the accompanying drawing.

In the arrangement shown in the drawing, the winch drum (not shown) drives a chain 1 which drives a lead screw 2. Mounted on the lead screw 2 is a nut 3 and there is a second lead screw 4 which extends parallel to the lead screw 2 and which extends through a generally rectangular aperture 3a in the nut 3. Mounted on the lead screw 4 is a first, adjustable, stop 5. A second, fixed, stop 6 is mounted on a smooth extension 4a of the lead screw 4. The position of stop 5 is adjustable by rotating the lead screw 4 by either of its terminal handles 7. The stop 6 is used to determine the lowest position on the hoist to which the carriage will travel, and the adjustable stop 5 allows the upper limit of travel to be varied.

A gear selector lever 8 connected to a gear box (not shown) is mounted on the smooth portion 4a by means of a fork arrangement 9. The lever 8 has a lower sharpened end 8a which engages with a well portion 1 Oa of a spring arm 10. The spring arm 10 serves to hold the lever 8 in position.

To operate the hoist, either of the handles 7 are pushed or pulled and this has the effect of moving the lever 8 into either the up or down driving position. The nut 3 therefore moves and engages either of the stops 5 and 6. Continued movement of the nut 3 against the stops causes the lead screw assembly to move and return the lever back to the neutral position.

In either of the above described embodiments of hoist, the drive means will preferabiy be a small petrol or diesel engine, and the gear means will preferably be an infinitely variable gearbox. The use of an infinitely variable gearbox allows the drive from the drive means to be gradually applied to the loaded carriage as it starts its movement.

The drive means and gearbox will conveniently be mounted on a wheeled platform to allow the hoist to be moved easily.

It will be appreciated that the above described hoist will be provided with a safety brake to ensure that, should the winch cable snap, the carriage will be held in position on the track. Such a safety brake may for example be spring loaded into the on-position and held off by the tension of the winch cable.

Claims (7)

1. A conveying apparatus comprising conveying means selectively movable in first and second opposed directions, drive means allowing movement of said conveying means, gear means operatively associated with said drive means, which gear means has first and second positions for respectively controlling movement of said conveying means in the first and second directions and a neutral position at which said conveying means is stationary, and means for moving the gear means to the neutral position when said conveying means has moved a predetermined distance in said first or second directions.

2. Conveying apparatus as claimed in claim 1 wherein the conveying means comprises a carriage movable along an elongate track structure.

3. Conveying apparatus as claimed in claim 1 or 2 wherein the gear means has a selector lever with first and second positions for effecting movement of the conveying means in said first and second opposed directions and a neutral position.

4. Conveying apparatus as claimed in claim 3 wherein the means for moving the gear means comprises a driven rotary plate having apertures arranged on a circular locus and pegs arranged in the apertures each to move the selector lever back' to the neutral position when the conveying means has moved a predetermined distance in the selected direction.

5. Apparatus as claimed in any one of claims 1 to 3 wherein the means for moving the gear means comprises a driven rotary lead screw, an axially movable rod associated with the selector lever, said rod having a screw portion and being associated with an adjustable stop on said screw portion and an additional stop, and a nut movable by said first screw along said rod between said two stops to act thereagainst to effect movement of the rod to move the selector lever to the neutral position when the conveying means has travelled a predetermined distance in a selected direction.

6. Apparatus as claimed in any one of claims 1 to 5 wherein the gear means is an infinitely variable gear box.

7. Conveying apparatus substantially as hereinbefore described with reference to the accompanying drawing.