GB2121868A

GB2121868A - A flush hinge

Info

Publication number: GB2121868A
Application number: GB08316076A
Authority: GB
Inventors: Maurice Kinsman Tucker
Original assignee: UK Secretary of State for Defence
Current assignee: UK Secretary of State for Defence
Priority date: 1982-06-17
Filing date: 1983-06-13
Publication date: 1984-01-04
Also published as: GB8316076D0; GB2121868B

Abstract

A hinge capable of providing a large folding structure with two flush surfaces when opened through 180 DEG comprises two hinge blocks (1, 3) coupled by means of a swinging link (7), the rotation of each block relative to the link being limited to 90 DEG by a stop mechanism (8, 11) and sequenced by a restraining means (16). The hinge is specifically applied to a folding bridge to provide for the hinge block (1) to be attached to a bridge girder (21) pivotally supported upon a support member (23). The hinge block (3) is attached to a further bridge girder (24) which is adapted to be rotated in an anti-clockwise direction in Figure 2 by means of a linkage (32, 36) through hydraulic rams (not shown) <IMAGE>

Description

SPECIFICATION A flush hinge This invention relates to a hinge having two flush surfaces when opened through 1800 of rotation. In particular, but not exclusively, it is applicable to large structural units such as those of a folding bridge and is adaptable to a scissoring method of operation, i.e. a known method of folding and unfolding two structures interconnected by a hinge, by rotation of one of the structures about an axis remote from the hinge.

It is desirable that a transportable folding bridge should have in its unfolded state, both a flush bottom face to permit passage of the bridge across rollers during launching and a flush top face for ease of traffic flow across the bridge.

Simple hinges, commonly applied to existing bridges and many other folding structures have a single hinge pin and bush which are necessarily axially located in the plane of one of the faces in order to provide a full 1 800 rotation, and consequently the pin and bush must partially protrude from that face when the hinge is opened.

A more complicated type of hinge providing a flush surface at both faces when open through 1 800 is known for use with lightweight folding structures, e.g. table leaves or countertop flaps, in which the two adjoining portions of the structure are separately pinned to an intermediate swinging link in a plane lying between the two faces. This type of hinge opens erratically, rotation occurring indiscriminately at either one of the two hinge pins at any moment, and when a pair of the hinges are used in line, relative twisting of the two attached portions occurs. Consequently the hinge is only suitable for use with fairly lightweight structures that can be manually controlled during opening and closing.

The present invention seeks to provide a flush hinge of the swinging link type from which indiscriminate hinge pin rotation is eliminated.

In accordance with the present invention a flush hinge including a first and a second hinge block each having an end face with opposed first and second edges, which end faces and edges are mutually confrontable when the hinge is opened, and a swinging link rotatably attached at each of its ends to a respective one of the hinge blocks so as to be rotatable about an axis adjacent and parallel with the first edge of the respective end face, is further provided with a stop mechanism engageable between the link and each hinge block for limiting the angle of rotation between the link and the hinge block to substantially one half of the total angle of rotation between the two hinge blocks, and a restraining means operative between the link and the first hinge block so as to resist rotation therebetween so long as rotation of the second hinge block relative to the link is possible.

The link may be conveniently attached to the hinge blocks by a first and a second hinge pin respectively and the restraining means may comprise a pre-loaded torsion spring located at the first hinge pin. The strength of this spring need be sufficient only to overcome any differential hinge pin friction that exists and any moment that may be imparted by adverse hinge pin reactions arising in specific applications.

Preferably the end face of each hinge block is further provided with engagement means adjacent the second edge, which means may conveniently comprise co-operative male and female shear lugs, if the opened hinge is likely to be subjected to shear loads only. Alternatively, if the open hinge is also required to resist tensile loads the engagement means preferably comprises mutually alignable holes in each hinge block through which a pin can be inserted.

The hinge may be adapted for scissoring by means of a conventional scissoring attachment comprising a deflectable scissoring lever and a fixed fulcrum arm co-operative with the lever. The attachment is fastened to the second hinge block adjacent the second edge so as to project outwardly from the end face. When a pair of structures to which the hinge is applied is to be unfolded by the scissoring method the structure to which the first hinge block is attached is itself deflectably supported upon a support member at a pivot point remote from the hinge and the scissoring lever is also linked to the support member.If the hinge is scissored open by rotating the first hinge member downwardly through a substantially vertical quadrant above the horizontal plane of the supporting pivot point, the torsion spring at the first hinge pin can be omitted as the necessary restraining means is provided by the action of the dead weight of the second hinge member and its attached structure upon the link.

An embodiment of the invention will now be described by way of example only, with reference to the accompanying drawings of which: Figure 1 is a perspective view of a rotation controlled, swinging link hinge, Figure 2 is a side view of a similar hinge attached to a pair of bridge girders and adapted for scissoring operation, and Figures 3 to 6 are diagrammatic representations of the hinge of Figure 2, respectively depicted in the fully folded position, during the first 900 of opening, during the second 900 of opening, and in the fully opened position.

The hinge illustrated in Figure 1 comprises a first hinge block 1 having a recessed end face 2 and a second hinge block 3 having a recessed end face 4, each respectively pivoted by hinge pins 5 and 6 to a swinging link 7.

The available rotation of the link 7 with respect to the block 1 is limited to 900 by means of a stop pin 8 attached to the link 7 which pin is engageable with two limit notches 9 and 10 appropriately located in the recessed end face 2 of the block 1. Rotation of the link 7 with respect to the block 3 is similarly limited to 900 by an identical arrangement of a stop pin 11 at the other end of the link 7 and limit notches 12 and 13 in the recessed end face 4 of the block 3.

The end faces 2 and 4 are also provided with mating male and female shear lugs 14 and 1 5 respectively, which engage when the hinge is fully open, i.e. when the end faces 2 and 4 confront.

A preloaded torsion spring 1 6 comprising the restraining means, is connected between the block 1 and the hinge pin 5 so as to resist anticlockwise (as drawn) rotation of the link 7 relative to the block 1.

A similar hinge is depicted in Figure 2 applied to a pair of bridge girders. In this arrangement the hinge block 1 is attached to one end 20 of a near bridge girder 21, which girder is pivotally supported at its other end 22 upon a support member 23. The other hinge block 3 supports a far bridge girder 24.

This arrangement is adapted for scissoring operation by a scissoring attachment 30 comprising a fulcrum arm 31 to which one end of a scissoring lever 32 is rotatably attached at a scissoring pivot 33, the fulcrum arm 31 being fixed to the hinge block 3 by pins 34 and 35. The other end of the lever 32 is tied by a linkage 36 to the support member 23. In this particular arrangement the torsion spring 16 of Figure 1 is no longer necessary, as its function as a restraining means is performed by the pendent girder 24. Also, so that the fully opened girders will be resistive to tensile loads as well as shear loads, the male and female shear lugs 14 and 1 5 of Figure 1 are replaced by alignable eyes 37 and 38 respectively which may be interconnected by a locking pin 39 (see Figure 6).

Unfolding of the girders will now be described with reference to the Figures 3 to 6. When the folded bridge girders 21 and 24 are to be deployed they are first raised to the position shown in Figure 2 by a first hydraulic ram (not shown) provided on the support member 23. In this position the stop pins 8 and 11 are engaged with the notches 10 and 13 respectively. The near girder 21 is then rotated clockwise about its end 22 by further rams (not shown), which rotation causes the scissoring lever 32 to bear upon the fulcrum arm 31 thus rotating the far girder 21 anti-clockwise about its hinge pin 6 (Figure 3) until the stop pin 11 engages with the notch 12, by which time the girders have unfolded by 900.

No rotation can occur at the hinge pin 5 during this first 900 of unfolding because the clockwise turning moment imparted to the link 7 by the deadweight of the girder 24 acts to lock the stop pin 8 into engagement with the notch 10.

However, once the stop pin 11 engages with the notch 12 the anti-clockwise turning moment imparted to the girder 24 by the scissoring lever 32 is transmitted via the link 7 to the hinge pin 5 thus disengaging the stop pin 8 from the notch 10 and transferring all further rotation to the hinge pin 5 (Figure 4). This rotation then continues throughout the second 900 of unfolding (Figure 5) until the stop pin 8 engages the notch 9, whereupon the girders are fully unfolded (Figure 6). The locking pin 39 can then be inserted in the aligned eyes 37 and 38 and the scissoring attachment 30 may also be removed if desired.

During the second 900 of unfolding (Figure 5), the scissoring lever 32 ceases to bear upon the fulcrum arm 31 and pulls directly on the scissoring pivot 33 to draw the far girder 24 and the link 7 into alignment with the near girder 21.

Refolding of the bridge is accomplished by reversing the whole process. Because the arrangement is totally symmetrical, including the scissoring attachment, the refolding may be done from either end of the bridge.

Claims

1. A flush hinge including a first and a second hinge block each having an end face with opposed first and second edges, which end faces and edges are mutually confrontable when the hinge is opened, and a swinging link rotatably attached at each of its ends to a respective one of the hinge blocks so as to be rotatable about an axis adjacent and parallel with the first edge of the respective end face: further provided with a stop mechanism engageable between the link and each hinge block for limiting the angle of rotation between the link and the hinge block to substantially one half of the total angle of rotation between the two hinge blocks, and a restraining means operative between the link and the first hinge block so as to resist rotation therebetween so long as rotation of the second hinge block relative to the link is possible.

2. A flush hinge as claimed in Claim 1 wherein the link is attached to the hinge blocks by a first and a second hinge pin respectively.

3. A flush hinge as claimed in Claim 2 wherein the stop mechanism comprises a stop pin attached to the link and engageable with two limit notches in the respective hinge block.

4. A flush hinge as claimed in Claim 3 wherein the restraining means comprises a pre-loaded torsion spring located at the first hinge pin.

5. A flush hinge as claimed in Claim 3 having a first and a second structure respectively attached to the first and the second hinge blocks, and adapted for opening by a scissoring method in a substantially vertical plane about a pivot support point of the first structure, wherein the restraining means is comprised by the weight of the second structure acting upon the link.

6. A flush hinge as claimed in any one of the preceding Claims wherein the end face of each hinge block is further provided with engagement means adjacent the second edge.

7. A flush hinge as claimed in Claim 6 wherein the engagement means comprises cooperative male and female shear lugs.

8. A flush hinge as claimed in Claim 6 wherein the engagement means comprises mutually alignable holes in each hinge block through which a pin can be inserted.

9. A flush hinge substantially as hereinbefore described with reference to the attached Figure 1.

10. A flush hinge substantially as hereinbefore described with reference to the attached Figures 2 to 6.