IE903443A1 - Manhole cover lifting device - Google Patents

Abstract

A device for lifting an object 40 comprises an elongate frame 10 with at least one wheel 13 at each end that is formed to straddle the object 40 to be lifted, load engagement means 110 suspended on the frame, and means 14 to swing the frame in an arc about the axis of the wheels, so as to lift the object engaged by said means. Preferably a pair of such devices having stops are used to lift the object until the stops immobilise the frame. The device can be used with only one wheel on a surface and then a lifting lever (14) raised in an arc until the other wheel touches the surface.

Description

The present invention relates to lifting devices and more particularly to manually operated devices for lifting manhole covers and the like.

To remove a manhole cover it is necessary to apply a considerable upward force to break the seal that forms between the manhole and the cover, and then to lift the cover, it is difficult to apply sufficient force using conventional hand tools. The present invention seeks to overcome this problem.

A device for lifting an object, comprising an elongate frame with at least one wheel at each end that is formed to straddle the object to be lifted, load engagement means suspended on the frame, and means to swing the frame in an arc about the axis of the wheels, so as to lift the object engaged by said means.

In a preferred arrangement the device supports the full weight of the object when the object is raised to its greatest height. Two of these devices may be used together to lift heavier objects.

According to a further aspect of the invention there is provided a device having two wheels mounted on each end which straddles an object lying on a surface.

To engage the object the device ie pivoted until only one of the wheels on each end is on the surface; the frame is then swung in an arc until all of the wheels are on the surface.

In preferred arrangements of both aspects of the invention the means to swing the frame in an arc is a lever. The engagement means is a hook like member that is rotatably mounted on the frame that stays substantially vertical during the lifting process.

In order that the invention and its various other features may be understood more easily, embodiments thereof will now be described by way of example only, with reference to the drawings, wherein :Fig.l is a side elevation of a lifting device according to a first embodiment of the invention, engaging a manhole cover in the lowered position; Fig.2 shows a similar elevation to that in Fig.l, but with the cover in the raised position; Fig. 3 is a view from direction 3 in Fig.2 showing the parts of the device adjacent to the middle and end portions thereof; Fig.4 shows in side elevation the use of two devices according to the first embodiment of the invention; and Fig.5 shows a side elevation of a device according to a second embodiment of the invention.

The device shown in Figure 1 comprises a frame 10 comprising a top bar 11 and two end plates 12. A wheel 13 is mounted on each end plate and a lever bar 14 is rigidly attached to the mid point of the top bar, but is at an angle to the plates 12. The frame 10 straddles the manhole 20.

Two L-shaped members 110 are rotatably mounted on the top bar ll. Each L-shaped member supports a removable key member 111 having a cylindrical end portion 112.

There is a longitudinal slot 113 in each L-shaped member and a lip 114 prevents the key member 111 moving along the slot 113 when lifting takes place. The L-ehaped members can be slid along the top bar to alter their separation.

To lift a manhole cover the lifting device is first moved so that the wheels 13 straddle the manhole and the key members are arranged so that they are supported by the L-shaped members 110 and will not move during lifting (Fig.l). The key members 111 are then inserted into lifting slots 41 on the cover 40. The lever bar 14 is then pushed towards the vertical position and beyond. This rotates the end plates 12 about the centres of the wheels and raises the key members 111 and the cover; a large mechanical advantage is obtained due to the relative lengths of plates 12 and lever bar 14. Throughout lifting the engaged portions 113 of key members remain in the vertical position. When the end plate 12 is in the vertical position all of the weight of the cover is supported by the lifting device (Fig.2). The device is easily balanced in this position using the lever bar 14 and can be rolled away from the manhole 20.

A variant of this device for use with heavier covers is shown in Fig.4. The device comprises two frames 50,60 of the type shown is Figures 1 to 3. Each frame has a removable lever bar 14 (only one shown fitted in Fig.4) that engages a circular recess 51 on a heel block 52 that is rigidly secured to the top bar 11. An adjustment screw 53 passes downwards through the block.

In use, each of the frames 50,60 is used to lift a portion of the cover 40 in the manner described.

However, each of lever bars 14 is moved over top centre until the end plates 12 pass the vertical position and the screws 53 in the heel block 52 abuts the top of the cover (Fig.4). In this position the plates 12 cannot rotate any further and the lever bars can be removed from the heel blocks and the cover rolled away from the manhole 20 . The height at which the devices support the cover can be altered using the adjustment screws 53.

A second embodiment of the invention is shown in Figure . The device comprises a single frame having a top bar 11, lever bar 14, L-shaped members 110 and key members 111 as described for the first embodiment of the invention. In this case, however, two triangular end plates 72 carry two wheels 73 each.

The device is used in a similar fashion to that illustrated in Fig.l. To engage the key members ill in a cover 40 in the lowered position, the device must be pivoted until only one of wheels 73 on each end plate 72 is on the ground. The lever bar 14 is then moved towards the vertical position and beyond until both of the wheels 73,74 are on the ground (Fig.5). In this position all of the weight of the cover is taken by the device, and the device becomes a stable trolley with which to move the cover.

All of the devices described have the advantage that they support the entire weight of the cover 40 once it has been lifted. The device illustrated in Figures 1 to 3 only needs steadying when in the raised position; the devices in Figures 4 and 5 form a stable trolley with which a covers can be moved.

The lever bars illustrated in the drawings can be modified to make it easier to move the cover away from the manhole after lifting; they may be T shaped or be in the form of a loop of tubular material.

To allow more workers to lift a heavy cover, two or more lever bars can be fitted to the top bars 11 on the devices described15 The device shown in figure 5 can have three or more wheels along the base 75 of each end plate 72. Two of the devices shown in figure 5 could be used to make a device similar to that shown in figure 4. Both of these modifications spread the weight of the cover more evenly on the ground.

The device described may be used to lift objects other than manhole covers. Magnets or suction pads can be fitted to the key members ill to lift ferrous metal and concrete objects respectively.

Claims (5)

1. l. A device for lifting an object, comprising an elongate frame with at least one wheel at each end that 5 is formed to straddle the object to be lifted, load engagement means suspended on the frame, and means to swing the frame in an arc about the axis of the wheels, so as to lift the object engaged by said means. 10
2. 2. A device according to claim 1, wherein, the device supports the full weight of the object when the object is raised to its greatest height.
3. 3. A device according to claims 1 or 2, wherein the 15 device has two or more wheels mounted in line on each end, and wherein to raise the object the device is pivoted until only one of the wheels on each end is on the surface and then the frame is swung in an arc until all of the wheels are on the surface.
4. 4. A device according to any preceding claim, wherein the means to swing the frame in an arc comprises a lever. 25 5. λ device according to any preceding claim, wherein the engagement means comprises a hook like member. 6. A device according to claim 5, wherein the hook like member is rotatably mounted on the frame, and stays 30 substantially vertical during the lifting process. 7. A device according to claim 1, and to any of claims 3 to 6 when appended thereto, further comprising stop means to limit the size of the arc through which the frame can swing. 8. A device according to claim 7, wherein the means to swing the frame in an arc are detachable. 9. A device substantially as described herein, with 10 reference to Figures 1 to 3 of the drawings. 10. A device substantially as described herein, with reference to Figure 4 of the drawings. 15 ll. A device substantially as described herein with reference to Figure 5 of the drawings. 12. a method of lifting an object using two devices according to claims 7,8 or 11, comprising the steps of 20 engaging the object with both devices and lifting it until each frame is immobilised by the respective stop means. 13. The features described in.the foregoing specification, or any obvious equivalent thereof, in any
5. 5. Novel selection. PETER DAVID IRISH FIVE SHEETS SHEET QNE