GB2035428A - Trap door assembly - Google Patents

Abstract

A trap-door assembly suitable for use in a pavement and giving access to an hotel cellar comprises a metal frame 10, 12, a door 2 pivoted on pins 22 attached to an angle bracket 20 and an inverted V-section stop 30; the pins are retained in L-shaped slots 24 in the frame members 10. During opening the door it first pivots on the pins until the edge 18 of the bracket contacts the stop 30 when the pins slide first horizontally then vertically down, the door is then held in the vertical position by the stop 30 and the top edge of member 12 (Figure 4). To close the door it is lifted and tilted until the other end of bracket 20 contacts stop 30 when the pins are forced back into the closed position. <IMAGE>

Description

SPECIFICATION Improvements relating to trap doors The invention relates to trap doors and particularly but not exclusively to trap doors for use in areas to which the public have access.

As an example of the use of a trap door in an area accessible to the public, reference may be made to a trap door set in a pavement outside an hotel and leading to the cellars of the hotel. In such situations there is a danger, if the trap doors on opening hinge through 1800 and lie flat, that passers-by may be unaware of the uncovered opening and fall through, and it has therefore been proposed to provide trap door assemblies of which the doors, when open, are retained in a stable upright position and thus provide an indication of the existance of an open door and a partial barrier against accidental falling through the opening.The devices hitherto employed to achieve this objective have been either complicated and therefore expensive to manufacture or have been unreliable in operation and it is therefore an object of the invention to provide a trap door having the above described advantageous feature and in which the disadvantages mentioned above are obviated or minimized.

According to the invention there is provided a trap door assembly comprising means defining a door frame, a door pivotally mounted in the frame means, means effective on pivoting the doorfrom a horizontal position within the frame to an upright position to move the door successively horizontally and vertically downwardly, and means for supporting the downwardly moved door in a stable upright position. The door moving means preferably comprise guide means and means for displacing the door under the influence of the guide means.

Preferably the door is pivoted by a pair of horizontal pins, and the guide means comprise means defining a pair of slots in which the pins are capable of sliding. Each of the slots may comprise two legs at an angle to one another, the first leg being substantially horizontal at least with the door upright. The second leg is preferably at right angles to the first leg. Preferably the slots are provided in the frame means.

The displacing means preferably comprises a pivot and a lever engagable with the pivot on raising the door.

Further means may be provided whereby, on the door being raised from its stable upright position and pivotally lowered towards a horizontal position, the door is moved horizontally in a direction opposite to the first mentioned horizontal movement. The said further means may comprise a further pivot and a further lever engageable with said further pivot on pivotally lowering the door.

The door frame means may further comprise support means for maintaining the door in a stable upright position in the event of failure of one or both pins.

Embodiments of the invention will now be described by way of example and with reference to the accompanying drawings of which: Figure 1 shows one embodiment of the invention in plan; Figure 2 is a section along line Il-Il of Figure 1; Figure 3 is an enlarged partial view of elements shown in Figure 2 during opening of the door; Figure 4 shows the elements of Figure 3 with the door in its fully opened position; and Figure 5 shows the same elements during the closing of the door.

As shown in Figure 1 the door assembly comprises a door 2 having a recessed handle 4 near the opening edge 6, the door being surrounded by a frame 8 comprising channel-sectioned side members 10 and channel-sectioned end members 12. The channels ofthe side members 10 are open outwards and the channels of the end members 12 are open inwards.

The door is supported in its closed position along portions of the side edges 16 by angle brackets 14 secured to frame side members 10. A further length 20 of angle iron is welded to the underside of the door 2 at the end 18 opposite to the opening end 6.

The downwardly extending web of this angle iron supports a pair of pins 22 which project outwardly of the door and are slidably mounted in slots 24 in the vertical portions of door frame side members 10.

As shown in Figure 2 the slots 24 are angled and comprise a horizontal first leg 26 and a vertical second leg 28. As also shown in the Figure, the angle bracket 20 extends beyond edge 18 of door 2 and overlaps with door frame end member 12 so as to form a dirt-proof joint when the door is closed asshown. Also when in the Figure is a stop 30 of inverted-V section which projects inwardly from the inner face of the door frame side member 10 and of which functions are described below.

In Figure 3 door 2 is shown in solid line having been turned about 300 from the horizontal with the rotation of pin 22, which is of circular cross-section and is welded to angled member 20, rotating in the slot 24 at the end of horizontal leg 26 removed from vertical leg 28. The same figures shows in phantom lines the relationship of the various components when the door has been raised to about 600from the horizontal with the pin 22 in the same position relative to the slot 24.At this position it will be seen that the angle member 20 abuts against the stop 30 which is in a fixed position relative to the slot, and it will be appreciated that the point of contact between angle member 20 and stop 30 will become the pivot for any further anti-clockwise movement of door 2 and in consequence pin 22 will be slid along horizontal leg 26 of slot 24 in the direction to the left in Figure 3 until it reaches the vertical leg 28;.lot is arranged that this position is reached with the door substantially vertical, and the door is then loweredwith the pin sliding downwardly into the vertical leg 28 of slot 24, a position shown in Figure 4.

Figure 4 shows the door in a stable upright position, supported by the engagement of pin 22 against the end of leg 28 of slot 24 and being inhibited against substantial rotation by the proximity of stop 30 to the angled member 20 and of the door 2 itself to the inwardly directed top and bottom flanges of channel-sectioned door frame end mem ber 12. In the event of a failure of pin 22, stop 30 provides an alternative support for the door and prevents its falling into the space below the door opening.

To close the door, the door is first raised vertically until the pin 22 lies at the junction of the legs 26 and 28 of slot 24, at which position a downward rotary movement to the right in Figure 4 is possible. As the door is lowered, the downwardly extending flange of angled member 20 engages the right-hand slope of stop 30 as shown in Figure 5, so that the door pivots about that point of contact and the pin 22 is slid along the horizontal leg of the slot 24 as the door is lowered towards its horizontal position within the frame 8.

Whilst the description in relation to the Figures 3,4 and 5 have referred only to one slot, it is to be understood that a corresponding slot and cooperating pin together with. a lever arm in the form of angled member 20 and pivot in the form of stop 30 are also provided at the opposite edge of the door as shown in Figure 1. Whilst reference has been made to a pair of pins 22, it is clear that the invention also contemplates a pin which extends from one side of the door to the other and thus performs the function of a pair of pins and such a single pin is to be regarded as within the scope of this invention.

Whilst a door assembly comprising a single door has been described for simplicity, it will be understood that a pair of doors may be pivoted at opposite ends of an elongate door opening.

In embodiments-not shown the door itself may be provided with a plate extending vertically downwards at each edge adjacent one end, which plates have an angled slot of which one leg is parallel to the door and the other extends vertically upwards with the door in the horizontal position. These slots may co-operate in a like manner to that described above with a pair of pins extending inwardly from the door frame side members 10. With such an arrangement at least, it may be possible to provide two or more doors side-by-side within a single door opening.

Whilst reference has been made to the respective legs of the slot 24 being at right angles to one another, other embodiments of the invention may utilise slots of which the angle between the legs is acute or obtuse, for example, so that as the door is lowered to the stable upright position it is also given a horizontal component of movement. Whilst a stop 30 in the form of an inverted-V has been found effective, a stop with precisely defined cam surfaces may be utilised. Similarly, the stop-contacting surfaces of the angled member 20 may similarly be formed as a precisely-shaped cam surface.

Claims (11)

1. A trap door assembly comprising means defining a door frame, a door pivotally mounted in the frame means, means effective on pivoting the door from a horizontal position within the frame to an upright position to move the door successively horizontally and vertically downwardly, and means for supporting the downwardly moved door in a stable upright position.

2. A trap door assembly according to Claim 1 wherein the door moving means comprises guide means and means for displacing the door under the influence of the guide means.

3. A trap door assembly according to Claim 2 wherein the door is pivoted by a pair of horizontal pins, and the guide means comprise means defining a pair of slots in which the pins are capable of sliding.

4. Atrap door assembly according to Claim 3 wherein each of the slots comprises two legs at an angle to one another, the first leg being substantially horizontal at least with the door upright.

5. Atrap door assembly according to Claim 4.

wherein the second leg is at right angles to the first leg.

6. Atrap door assembly according to any one of Claims 3-5 wherein the slots are pivoted in the frame means.

7. A trap door assembly according to any one of Claims 2-6 wherein the displacing means comprises a pivot and a lever engagable with the pivot on raising the door.

8. A trap door assembly according to any one of the preceding Claims comprising further means whereby, on the door being raised from its stable upright position and pivotally lowered towards a horizontal position, the door is moved horizontally in a direction opposite to the first mentioned horizontal movement.

9. A trap door assembly according to Claim 8 wherein said further means comprises a further pivot and a further lever engageable with said further pivot on pivotally lowering the door.

10. A trap door assembly according to any one of Claims 3-9 wherein the door frame means further comprises support means for maintaining the door in a stable upright position in the event of failure of one or both pins.

11. A trap door assembly substantially as described with reference to the drawings.