GB2073813A - Improvements in hopper door mechanisms - Google Patents

Abstract

A hopper door mechanism, particularly for a railway wagon, comprises a pair of doors 12, each door being carried by two swinging support arms 13, 14 each having one end thereof connected to the door and the other end thereof mounted on the hopper for pivoting about an axis, whereby the door may be swung about said axes into and out of a position where it closes an outlet aperture in the lower part of the hopper, and a link 21 pivotally connecting one of the swinging support arms 14 to a crank 23 rotatable about a fixed axis, whereby rotation of the crank, manually or by power means, imparts swinging movement to the support arms 13, 14 and hence closing or opening movement to the door. The pivotal connections between the link 21 and the crank 23 and support arm 14 are such that the crank and link form a toggle mechanism which passes through an overcentre position as the door is moved into its closing position. <IMAGE>

Description

SPECIFICATION Improvements in hopper door mechanisms The invention relates to hopper door mechanisms and particularly, but not exclusively, to hopper door mechanisms for use on railway hopper wagons.

In door mechanisms for railway hopper wagons there are usually provided on the lower part of the hopper two symmetrically disposed doors which are pivotable towards and away from one another to close and open the outlet aperture at the bottom of the hopper.

In one known form of door mechanism, the doors are hinged along one horizontal edge and are swung downwardly about the hinge, from a substantially horizontal position, to open the hopper. The hinged doors are opened and closed by one or more links connecting each door to a rotatable crank arm on the hopper, and the arrangement of the link and crank arm is such that in moving each door to the closing position the crank arm and link act as a toggle mechanism, passing through an overcentre position. This prevents downward loads on the doors, from the material in the hopper, tending to force the doors open. However such an arrangement suffers from the disadvantage that, in order to close the hopper, the doors must be pivoted upwardly towards the outlet aperture.Consequently, it is virtually impossible to effect such upward pivoting movement against the pressure of material if such material is still being discharged from the hopper.

It is not therefore possible to close the hopper before discharge has been completed, shouid this be required, for example in an emergency. Also, the angular rotation of the crank arm necessary to effect full opening and closing movement of the doors is usually such that such movement cannot readily be effected by power means, such as a fluid energised ram, and a manually operated mechanism is therefore employed.

To overcome this difficulty of the pressure of material in the hopper tending to open the hopper doors, or prevent them closing during discharge, it has been proposed to mount the doors for pivoting movement about axes spaced above the doors so that the doors are swung sideways towards one another to close the outlet from the hopper. The swinging movement of the doors has normally been effected by manually operated gear mechanisms and it has been necessary to provide separate latch mechanisms to hold the doors in the closed position. Such an arrangement is disadvantageous since it is necessary for the operator to remember, after having closed the hopper doors, also to operate the latch mechanism.

The present invention provides an improved hopper door mechanism which avoids the disadvantages of both of the types of mechanism referred to above.

According to the invention a hopper door mechanism comprises a door, at least one swinging support arm having one end thereof connected to the door and the other end thereof mounted on the hopper for pivoting about an axis, whereby the door may be swung about said axis into and out of a position where it closes an outlet aperture in the lower part of the hopper, and a link connecting the swinging support arm to a crank rotatable about a fixed axis, whereby rotation of the crank imparts swinging movement to said support arm and hence closing or opening movement to the door.

Preferably the door is supported by two swinging support arms mounted on the hopper for pivoting about spaced parallel axes, said one end of each said support arm being pivotally connected to the door, and said link connecting the rotatable crank to one of the support arms.

Preferably the ends of the link are pivotally connected to said support arm and crank respectively, for pivoting about axes parallel to said axis of pivoting of the support arm on the hopper.

Preferably the relative positions of the pivotal connections between the link and the crank and support arm are such that the crank and link form a toggle mechanism which passes through an overcentre position as the door is moved into its closing position. Thus, once the mechanism has been moved to the closing position, it cannot be moved to the open-position merely by pressure of material in the hopper on the door. Such pressure will tend to hold the mechanism more firmly in the closed position, and the door may only be opened by positive operation of the door mechanism.

Means may be provided for rotating said crank manually or by power means. For example the crank may be rotated by a fluid energised ram.

The door mechanism may comprise two assemblies each comprising a door, support arm or arms, link and crank, the cranks of the two assemblies being rotatable about a common axis.

For example, the cranks of the two assemblies may comprise different parts of a single crank member. Preferably the two assemblies are symmetrically disposed with respect to said common axis.

The invention includes within its scope a hopper, in particular a hopper on a railway wagon, including a door mechanism of any of the kinds referred to above.

An example of a door mechanism in accordance with the invention is shown schematically in the accompanying drawing.

Two door mechanisms of the kind shown in the drawing are provided, one at each end of the hopper.

The hopper, the side walls of which are indicated at 10, is formed at its lower end with outlet apertures 11 and associated with each outlet aperture is a swinging arcuate door 1 2. At each end of the hopper each door 12 is supported by two swinging support arms 13 and 14 the lower ends of which are pivotally connected at 1 5 and 1 6 respectively to spaced locations on the door, and the upper ends of which are pivotally connected at 1 7 and 1 8 respectively to brackets 19 and 20 fixedly secured in relation to the hopper. Thus each door 12 may be swung on the arms 13 and 14 from the closed position, shown in solid lines in the drawing, to the open position, indicated in chain lines.

Intermediate the ends of the link 14 is pivotally connected, at 21a, one end of a curved link 21, the opposite end of which is pivotally connected at 22 to the end of a crank arm 23 which is secured to a shaft 24 extending along the centre line of the hopper.

The link 21 of the left hand door closing mechanism extends over the shaft 24 and the corresponding link 21 of the right hand mechanism extends below the shaft 24, so that the links are arranged substantially symmetrically with respect to the shaft.

As the shaft 24 is rotated anti-clockwise (in the particular arrangement shown in the accompanying drawing) the doors 12 will be swung outwardly on the support arms 13 and 14 to the open positions indicated in chain lines. The shaft 24 may be rotated by a conventional manually operated mechanism. However, since the angular movement of the crank arm 23 necessary to effect full opening movement of the doors is only of the order of 1200, the shaft 24 may readily be operated by power means such as an hydraulic or pneumatic ram. Such a ram may be connected to a further crank arm mounted on the shaft 24 or may be directly connected to one of the crank arms 23.

It will be appreciated that the axes of all the pivotal connections are horizontal and parallel.

The disposition of the pivotal connections between the link 21, the crank arm 23 and the support arm 14 are such that the link 21 and crank arm 23 act as a toggle mechanism, passing through an overcentre position as the mechanism moves to the closed position shown in the drawing. Thus downward pressure on the doors, when they are in the closed position, will tend to rotate the crank arms 23 further clockwise, so holding the doors more firmly in the closed position.

Due to the dispositions of the various pivotal connections with respect to the axis of the shaft 24, the paths of movement of the upper and lower curved links 21, relative to the points 21 a, will be different Consequently, if the crank arms 23 were to be of the same length, one door 12 would open further than the other. To compensate for this effect, the crank arm 23 connected to the lower curved link is preferably slightly longer than the crank arm connected to the upper curved link, as shown, so that the two doors open by equal amounts. It will be appreciated that the arrangement of the links 21 and crank arms 23 could be reversed so that door opening is effected by clockwise rotation of the shaft 24.

It will be seen that, during closing movement of the doors 12, they will swing laterally across the associated outlets from the hopper, making it possible for the door to be closed while the hopper is still discharging.

Claims (12)

1. A hopper door mechanism comprising a door, at least one swinging support arm having one end thereof connected to the door and the other end thereof mounted on the hopper for pivoting about an axis, whereby the door may be swung about said axis into and out of a position where it closes an outlet aperture in the lower part of the hopper, and a link connecting the swinging support arm to a crank rotatable about a fixed axis, whereby rotation of the crank imparts swinging movement to said support arm and hence closing or opening movement to the door.

2. A mechanism according to claim 1, wherein the door is supported by two swinging support arms mounted on the hopper for pivoting about spaced parallel axes, said one end of each said support arm being pivotally connected to the door, and said link connecting the rotatable crank to one of the support arms.

3. A mechanism according to claim 1 or claim 2, wherein the ends of the link are pivotally connected to said support arm and crank respectively, for pivoting about axes parallel to said axis of pivoting of the support arm on the hopper.

4. A mechanism according to any of claims 1 to 3, wherein the relative positions of the pivotal connections between the link and the crank and support arm are such that the crank and link form a toggle mechanism which passes through an overcentre position as the door is moved into its closing position.

5. A mechanism according to any of claims 1 to 4, wherain means are provided for rotating said crank manually.

6. A mechanism according to any of claims 1 to wherein means are provided for rotating said crank by power means.

7. A mechanism according to claim 6, wherein said power means comprise a fluid energised ram.

8. A mechanism according to any of claims 1 to 7, wherein there are provided two assemblies each comprising a door, support arm or arms, link and crank, the cranks of the two assemblies being rotatable about a common axis.

9. A mechanism according to claim 8, wherein the cranks of the two assemblies comprise different parts of a single crank member.

10. A mechanism according to claim 8 or claim 9, wherein the two assemblies are symmetrically disposed with respect to said common axis.

11. A hopper door mechanism substantially as hereinbefore described with reference to the accompanying drawings.

12. A railway wagon hopper including a door mechanism according to any of the preceding claims.