GB2146563A - Drive reversing device - Google Patents

Abstract

A drive reversing device (10) comprises a housing (20) from opposite sides of which two coaxial shafts (11,13) extend, one shaft (11) being received in a hand tool such as a power drill and the other shaft (13) having a bore (29) to receive a screw fastener device driving tool. Within the housing (20) the shafts (11,13) are drivingly coupled by a pinion (24) on one shaft (11) engaging a spur wheel (12) located in the housing (20) and in turn engaging an internally toothed ring (25) secured to the other shaft (13), the rotation of the first shaft (11) thereby being reversed and reduced as it is transmitted to the second shaft (13). <IMAGE>

Description

SPECIFICATION Drive reversing device This invention relates to drive reversing devices and in particularto a device for use in removing screws, bolts, nuts or the like.

In addition to the use of screwdrivers or spanners by hand, it is known to use power tools specifically adapted for the abovementioned purpose. The use of power tools in this context is particularly advantageous in the event that a large number of screws, nuts or the like are to be removed, since in such a case the use of hand tools can be arduous and cause discomfort to the operator. However, to avoid the cost of purchasing several power tools for performing different functions, it is also known to use attachments for a single power too such as a drill, each attachment performing one specific function.

British patent publication No. 2088264A and our co-pending application No. 8324517 (Serial No 212771 it) describe such attachments.

However, for the removal of screws, nuts orthe like it is necessary, whether using a power tool specifically adapted for tightening such screws, nuts or the like or using a power tool, such as a drill, with an attachment for such purpose, that the power tool is drivable in the reverse direction from the normal drilling or screw-tightening direction. With such power tools it is customary to provide for the tool to run in the reverse direction by alteration of the polarity of the drive motor. The electrical circuit provided for such polarity reversal usually incorporates a resistor which results in a reduced power being available when reverse is engaged. Such an arrangement is not suitable for use with large screws, nuts orthe like since motor failure can readily occur.

It is an object of the present invention to provide a drive reversing device which avoids or mitigates to a substantial extent the above disadvantages.

The invention provides a drive reversing device comprising a housing, a first shaft rotatably mounted in said housing to extend therefrom and adapted to be received in the jaws of a rotary machine and a second shaft rotatably mounted in said housing to extend therefrom to a tool part adapted to engage a screw, nut or the like, said first and second shafts each having a gear wheel disposed thereon and within said housing, said gear wheels being drivingly coupled to each other whereby rotation of said first shaft in one direction causes rotation of said second shaft in the reverse direction.

By screw, nut or the like is intended to include screws, for example wood screws, bolts, studs, nuts or the like having a screw threaded portion and having a slot, a recess or an outer form adapted to receive a screwdriver blade, Allen (R.T.M.) key or spanner for the purposes of tightening or removing the same.

Preferably said first and second shafts extend coaxially from opposed sides of said housing. In this case one of said gear wheels may comprise a pinion and the other of said gear wheels comprise an internally toothed ring, with a spur wheel disposed between and engaging said pinion and said ring.

The pinion and the spur wheel may have an equal number of teeth thereon and said ring may have at least twice as many teeth thereon as said pinion.

Preferably the ring has three times as many teeth thereon as said pinion.

Said tool part may be detachably secured to said second shaft.

Said housing may have a threaded bore therein extending transversely of the axis of said shafts, and a handle may be provided adapted to be received in said threaded bore.

The invention will now be described with reference to the accompanying drawing, in which: Figure 1 is an elevation in axial section of one embodiment thereof, and Figure2 is a section on line ll-ll of Figure 1.

The Figures show a drive reversing device 10 comprising a housing 20 which is in two parts for ease of assembly, a body 18 and a cap 14 secured to each other by three screws 19. Lugs 21 engaged in recesses 22 also serve to locate cap 14 relative to body 18.

A first shaft 11 is rotatably mounted in housing 20 and extends therefrom in a part 23 which is adapted to be received in the jaws of a drilling machine (not shown) in conventional manner. Part 23 of shaft 11 may be of any suitable cross-section such as circular, square or preferably hexagonal. The other end of shaft 11 is disposed within the housing 20, shaft 11 passing through a bush 16 located in the cap 14. The part 24 of shaft 11 within housing 20 is formed as a pinion having 11 teeth of module 1 mm and 20 pressure angle.

Also located in cap 14 is a second bush 15 in which is rotatably mounted an idler gear 12 also having 11 teeth of module 1 mm and 20 pressure angle and in driving engagement with pinion 24. In consequence idler gear 12 rotates at the same speed but in the opposite direction to shaft 11.

A second shaft 13 is also rotatably mounted in the housing 20 and extends from the body 18 in a direction opposed to that of shaft 11 but axially aligned therewith. The shaft 13 has a cup-shaped end part 25 disposed within the housing 20 and having 33 teeth of module 1 mm and 20 pressure angle disposed around the inner surface thereof. The toothed ring of part 25 thus formed is drivingly engaged with idler gear 12 so as to rotate in the same direction but at one third of the speed of idler gear 12. In consequence shaft 13 rotates in the opposite direction to shaft 11 but at one third the speed thereof. Within the cup-shaped end part 25 is disposed a bush 17 which receives the end 26 of shaft 11 to provide an end bearing therefor.

Also provided in the body 18 is a screw-threaded blind bore 27 into which a handle (not shown) may be screwed so as to extend therefrom in a direction perpendicular to the axis of shafts 11,13. Such handle acts as a supportforthe drive reversing device in use.

The end 28 of shaft 13 disposed outside the housing 20 may be formed as a screwdriver blade, Allen (R.T.M.) key or may be of suitable crosssection, for example square or hexagonal, to receive a socket spanner. However in the embodiment shown the end 28 is provided with a hexagonal bore 29 into which a screwdriver blade, Allen (FI.T.M) key, socket spanner drive shaft or the like may be inserted. Alternatively a tool driving device as described in our co-pending application number or a tool as described in British patent publication number 2088264A may be inserted as required.

By means of the invention screws, nuts and the like may be readily removed using a conventional power drill which does not have a reverse drive facility, or without using such facility in the case of use with large screw, nuts or the like.

In addition the device can be used, with a drill having a reverse drive facility, as a speed reducing device, for example when drilling masonry or the like.

Claims (15)

1. A drive reversing device comprising a housing, a first shaft rotatably mounted in said housing to extend therefrom and adapted to be received in the jaws of a rotary machine, and a second shaft rotatably mounted in said housing to extend therefrom to a tool part adapted to engage a screw fastening device, said first and second shafts being drivingly engaged within said housing whereby rotation of said first shaft in one direction causes rotation of said second shaft in the reverse direction.

2. A drive reversing device according to claim 1 wherein said first and second shafts extend coaxially from opposed sides of said housing.

3. A drive reversing device according to claim 2 wherein within said housing said first and second shafts each have a gear wheel disposed thereon, said gear wheels being drivingly coupled to each other.

4. A drive reversing device according to claim 3 wherein one of said gearwheels comprises a pinion and the other of said gear wheels comprises an internally toothed ring and a spur wheel is disposed between and drivingly engaged with said pinion and said ring.

5. A drive reversing device according to claim 4 wherein said pinion is rotatably mounted in a fixed location within said housing.

6. A drive reversing device according to claim 4 or claim 5 wherein said ring is formed in a cupshaped part of one of said shafts and having a bush therein providing an end bearing for the other of said shafts.

7. A drive reversing device according to any one of claims 4 to 6 wherein said pinion and said spur wheel have an equal number of teeth thereon.

8. A drive reversing device according to claim 7 wherein said ring has at least twice as many teeth thereon as said pinion.

9. A drive reversing device according to claim 8 wherein said ring has three times as many teeth thereon as said pinion.

10. A drive reversing device according to any one of claims 4 to 9 wherein said ring is disposed on said second shaft.

11. A drive reversing device according to any one of claims 1 to 10 wherein said tool part is detachably secured to said second shaft.

12. A drive reversing device according to any one of claims 1 to 11 comprising a handle secured to said housing.

13. A drive reversing device according to claim 12 when dependent on claim 2 wherein said housing has a threaded bore therein extending transversely of the axis of said shafts and said handle is received in said threaded bore.

14. A drive reversing device according to any one of claims 1 to 13 wherein said housing comprises a body and a cap detaachably secured thereto.

15. A drive reversing device substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.