GB2189763A - Electric cable storage in balancer - Google Patents

Abstract

A balancer for supporting an electrically-driven device includes a spring loaded drum (1) onto which the electric supply cable (7) of the device is wound for storage. The device is supported by a steel rope (4) which is wound on a drum (3) connected to a spiral spring (2) to balance the weight of the device. The tension of the spring is adjustable. <IMAGE>

Description

SPECIFICATION Balancer This invention relates to a balancer.

Balancers are used in workshops and similar places for supporting a device during use by an operator. Since all or most of the weight of the device is supported by the balancer the operator can use the device more accurately and for longer lengths of time (continuous or broken).

Balancers also allow the device to be placed in a safe position ie one where the operator is less likely to be harmed by the device, while not in use.

Additionally the device is less likely to be damaged by other workshop equipment e.g. a passing fork-lift truck.

If the device is electrically-powered the electrical cable connected to the device may also be a source of danger. For example the cable may become damaged by the device itself or by otherworkshop equipment unless positioned safely.

According to the invention a balancer comprises means for providing a force for supporting substantially all or most of the weight of electrically driven device and for moving the excess length of electric cable providing power to the device to a store.

Preferably the force is provided by a spring,the tension of which maybe adjusted by suitable means to substantially counterbalance the weight of the device and/or cable.

The store forthe excess length of electric cable may be a drum which is located within the balancer itself and which is rotatable under the influence of the spring.

The balancer may also provide a further store for a member providing support between the device and the balancer. The member may conveniently be a steel rope which is movable into the balancer under the influence of the spring.

In use the balancer is preferably positioned in a safe position such as on an overhead beam.

Examples of devices which may be supported by the balancer include drills, sanders, grinders and paint sprayers.

One embodiment ofthe invention will now be described byway of example only, with reference to the accompanying drawings,ofwhich:- Figure 1 shows an exploded, perspective view of a balancer according to the invention, Figure2 shows slip rings inside the balancer cover, Figure 3shows a ratchet and pawl on the outside ofthe balancer, Figure 4 shows the hookforsupporting the device, Figure 5shows a device, in this case a sander, supported by the balancer, and Figure 6shows a side view of part of the balancer shown in figure 6.

As shown in Figure 1 the balancer comprises a storage drum 1 providing a store for a length of electric cable, a spiral spring 2 in operative connection with the storage drum 1 and located inside a sub-housing 3 ofthe balancer, a member in the form of a steel rope4connectingthe balancerto the device being supported and a cover consisting of three connectable rigid housings H1, H2 and H3 made of material such as steel, aluminium or reinforced plastic.

The storage drum 1 comprisestwoannularflanges 5 and 6 between which turns ofthe electric cable 7 connecting the device to the balancer may be wound for safe storage. One end of the cable sheath is removed to disclose two separate insulated wires 8 and which arefedthrough a suitable aperture (not shown) in the centre of the drum 1 and connected to electric screwterminals 10 and 11 located at one side ofthedrum 1.The bared ends ofthetwowiresare clamped in position by the screws of the screw terminals in conventional manner and each of the screws also locates pairs of small leaf springs 12,13, and 14, 15. At the ends of the leaf springs further from the screw terminals are stud contacts 16, 17 and 18, 19 which are so positioned that each pair of contacts (as shown in the drawing) is pressed into sliding engagement with one of two concentric slip rings 20 and 21. These slip rings (shown in detail in Figure 2) are located insidethe housing H2 and insulated therefrom by a backing disc 22. Two terminals (only one, 23, being apparent in the drawing) connected to the rings lead through the housing H2.Bared leads fro afurthercable70 (shown in Figure6) connectthe rings via these terminals to a junction box 71 and thence to the external electrical supply.

As stated above, only one terminal 23, is apparent from Figure 1 and the cable 70 connecting the junction box 71 passes through the channel 24 ofthe circular flange 25 on the outside of the housing H2 and through the notch 26 at the edge of the housing H3 which is an interference fit on the flange 25.

The terminals 10,11, leaf springs, 12,13 and 14,15, and studs, 16,17 and 18, 19are all located within a cylindrical flange 27 formed on the side of the drum 1.Thisflange 27 is a sliding fit inside a cylindrical recess 28 on the inside of the housing H2. The drum 1 is thus located by the housing H2 but is free to rotate therein.

The cable stored on the drum passes outthrough the near-rectangular aperture 29 in the housing H2 and thence to the device, eg. a sander, supported by the balancer.

The two flanges 5 and 6 of the drum 1 are teach provided with three holes 30,31 and 32 (in flange 5) and 33 (onlyone apparent) (inflange6)equally spaced apart around the flange edges. Each hole in oneflange 5 is in axial alignment with a hole in the otherflange 6. Three screws 34,35 and 36 each pass through a pair of aligned apertures into one ofthree screw-threaded apertures 37,38 and 39 in the sub-housing 2. The drum is thus secured to the sub-housing and rotates with it.

The sub-housing 2 is shaped so that on the side adjacent the drum 1 there is an annular recess 40 defined by a cylindrical flange 41. The recess 40 houses the spiral spring 2the outer end 42 of which is turned backto locate against a side 43 of a gap in the flange 41.

Ashort length 45 ofthe inner end ofthe spiral 2 is bent so asto extend radially ofthe sub-housing 3, and is located in a slot 44 in a spindle 46 connected to and located within the housing H1 The sub-housing rotates on the spindle the spring is thus prevented from rotating or otherwise moving within the recess 40 in the sub-housing but may be tensioned by rotation ofthespindle46.

The outer surface of the sub-housing 3 istapered and has the general shape of part of a cone. In the surface is formed a spiral groove 47 for receiving turns of the steel rope 4which is connected to the device to be supported bythe balancer. The end of the rope is formed with an eniarged nipple 146 which is located in a slot 143 formed in the sub-housing 3 and thereby serves to securetheend of the rope to the sub-housing.

The spindle 46 is located on the central axis ofthe balancer and the end (not shown) furtherfrom the slot 44 is fixed to the housing so as not to slide axially but can rotate relative thereto. This outer end ofthe spindle is connected to a four-toothed ratchet 47 (see figure 3) located on the outside ofthe housing H1.

The ratchet 47 engages with a pawl 48 secured to the housing H1 byascrew49.

The outer end of the spindle 46 is also formed with a hexagonal recess 50. An Allen key (which is of hexagonal cross-section corresponding to the size and shape ofthe recess 50) may be inserted in the recess 50 and turned to rotate the sub-housing 3, and the storage drum 1 attached to it.

As can be seen in Figures 1 and 4the steel rope 4 passes out of the housing H1,through a slot 52 in an arm 99 attached to the housing H1.

The rope is provided at its lower end with a hook 60 by means of which the device to be supported is attached to the rope. An enlargement 51 is formed on the rope 4so that when fully wound into the balancer by rotating the sub-housing 3, this enlargement, being unable to pass through the slot 52, engages the arm thus preventing any more rope being taken into the balancer.

The housing H1, is provided with a hook64 by means ofwhich the balancer may be suspended from an overhead beam or the like. A loop ofwire (not shown) is then passed through the hook and an adjacent aperture 150 in a lug 151 by the housing H1, to preventthe balancerfalling accidentaly.The housing H2 is secured to H1, by means ofthree screws 80,81 and 82 each passing through an aperture 86 or 87 (onlytwo apparent) in the edge flange 88 of housing H2 and engaging in one ofthree holes 89,90 or 91 formed in protuberances 92,93 or 94 integrally formed with and located at the edge of the housing H1.

The balancer is shown in use in Figures 5 and 6 supporting a device, in this case a sander 61 incorporating a sanding disc 62. This is supported by the rope 4 to the balancer B which itself hangs from a hook 68 on a beam 69. The electric cable 7 extends upwards from the sander, secured to the rope by means of a clip 63 or a short piece of adhesive tape, to the balancer. A plug andocket connector 90 is provided for convenience in the cable. The balancer itself is electrically connected to the electric supply by means of a further length of cable 70 to junction box71.

In useofthe balancerthespindle46 isturned by means of an Allen key inserted in the hexagonal aperture 50. This rotates the sub-housing 3 and simultaneouslythe drum 1,to wind all the rope4on to the outside surface ofthe subhousing and the cable on the drum. The balancer is then suspended from the overhead beam, its height being adjusted so that the sander when supported thereon is above head height but sufficiently low to be reached by the operators upwardley-stretched hand.

An object having a weight equal to that of the device to be supported is then suspended from the hook 60 and the spindle turned furtherto tension the spring, the sub-housing being prevented from further rotation by the enlargement 51 engaging the arm 99. The spring tension is thus adjusted to provide a force sufficient to counter-balancethe weight ofthe device to be supported by the balancer.

The ratchet47 and pawl 48 prevent unwanted release of spring tension.

The object is then removed from the hook 60 and replaced by the device.

In a modified form of the invention (not illustrated) the pawl and ratchet on the outside of the housing H1,which mayslip if poorlymachined orworn is replaced by a worm and gear mechanism which allows the spindle to be rotated as required to tension the spring but which prevents unwanted reverse rotation of the spindle and thus release of spring tension.

Claims (7)

1. Abalancercomprising meansforprovidinga forceforsupporting substantially all or most ofthe weight of an electrically-driven power device and for moving the excess length of electric cable providing power to the device to a store.

2. Abalancer according to claim 1 whereinthe store comprises a drum.

3. Abalancer according to claim 2whereinthe drum is located within the balancer housing.

4. A balancer according to claim 2 or claim 3 wherein the drum is rotatable under the influence of a spring.

5. A balancer according to claim 4wherein the spring provides the said force.

6. A balancer according to claim 4 or claim 5 comprising tension-adjusting means for the spring to substantially counter-balance the weight of the device and/orthe cable.

7. A balancer substantially as described herein with reference to and as illustrated in the accompanying drawings.