FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
The Patents Rules  2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)

1. "" AN IMPACT TOOL ""

2.

1. (A) EASY TOOL LIMITED
(B) Ireland
(C) 14-16 William Street Galway Ireland

The following specification particularly describes the invention and the manner in which it is to be performed.

Introduction
The invention relates to tools 
DE 19901047 describes a chisel having a tubular housing through which the chisel head extends. US3735822 describes a manually actuated jack hammer with a recoil spring to establish a systematic rhythm for repeated impact blows.
An object of the invention is to provide improved effectiveness of tools  particularly manual tools without electrical power.
Summary of the Invention
According to the invention  there is provided a tool body comprising: a handle  a shank  a tool head or a coupler for a tool head  a hammer having a hammer part for impact   a receiver  and a spring for biasing the hammer to an upper operative position ready for use and for biasing the hammer receiver to an outer operative position.
In one embodiment  the return spring has sufficient strength to support the hammer in an operative position without user lifting.
In one embodiment  the return spring has sufficient strength to support the socket or tool head in an operative position when pointed overhead.
In one embodiment  the spring is extended in the hammer impact position.
In one embodiment  the spring is located within the shank.
In one embodiment  the receiver comprises a flange for impact with the hammer  and an elongate member protruding upwardly within the shank.
In another embodiment  the receiver elongate member is engaged with the return spring.
In one embodiment  a top end of the return spring engages the receiver elongate member.
In another embodiment  the hammer is connected to the return spring by a rod which is connected to the shank and extends into the receiver elongate member.
In one embodiment  the return spring is a coil spring through which the rod extends and a lower end of the return spring is engaged with the rod.
In one embodiment  the return spring is closed over a lower end of the rod.
In one embodiment  the tool body further comprises a locking mechanism for locking the hammer down.
In one embodiment  the mechanism is operated by pulling a trigger in the handle.
In one embodiment  a biased catch engages in a slot to lock the hammer.
In a further embodiment  the locking mechanism has a default locked position.
In one embodiment  the tool body further comprising a shock-absorbing spring.
In one embodiment  the shock-absorbing spring is within the hammer.
hi one embodiment  the shock absorbing spring extends between the shank and the hammer part for impact with the receiver.
In one embodiment  the hammer part is cylindrical  surrounding the shank.
In a further embodiment  the hammer is slides on and surrounds an elongate tube secured to the receiver.
In one embodiment  the tool further comprises means for adding weight to the hammer.
In one embodiment  the weight means comprises cylindrical sectors having features for engagement with the hammer when they surround the hammer.
In one embodiment  the features include a ridge and a groove.
In one embodiment  the tool body comprises a coupler for a tool head  the coupler comprising a hollow tube having and a catch in a side wall for engaging with a tool head inserted into the tube.
In one embodiment  the tube is shaped to receive a tool head at any of a plurality of orientations.
In another aspect  the invention provides a tool comprising a tool head and a tool body as defined above in any embodiment.
In one embodiment  the tool head comprises a shank shaped to fit within said tube and has a recess for engagement with the catch.
In one embodiment  the tool head shank has a plurality of recesses for engagement with the catch  to provide different tool head orientations.
Detailed Description of the Invention
The invention will be more clearly understood from the following description of some embodiments thereof  given by way of example only with reference to the accompanying drawings in which:-
Fig. 1 is a front view of a tool body showing various heads which may be coupled to it and additional weights which can be added to the hammer head when required;
Figs. 2 and 3 are cross-sectional sketches showing the tool body in compacted and extended positions  and Figs. 2(a) and 2(b) are two detailed views showing locked and unlocked tool positions;
Fig. 4 is a more detailed cross-sectional view showing a base of the body;
Fig. 5 is an exploded view showing in more detail the parts of the tool body;
Fig. 6 is a side view of a tool body of an alternative embodiment  Fig. 7 shows the internal parts of this tool body  Figs. 8(a) and (b) are exploded views  Figs. 9 and 10 is a set of cut-away section views  Fig. 11 is a view showing a variety of tool heads which could be used with the tool body  Fig. 12 shows a tool in use; and
Figs. 13 and 14 show alternative chucks for connection to a tool head.
Referring to Fig. 1 a tool body 1 has a coupler for engagement with any of a variety of tool heads such as a spade head 3  a hatchet head 4  a chaser head 5  an flat head chisel 6  a point chisel head 7  a fork head 8  scraper head 9 and hard rubber head 10. This drawing shows a pair of additional weights 11 for addition to a hammer for changing the hammer weight when desired.
The manner of coupling the tool head to the tool body 1 is not the subject of the invention and is known in the art. It involves using a chuck 31 of the known "SDS" type.
Referring now to Figs. 2 to 5  the tool body 1 comprises:
21  hollow shank around which there is a steel washer 38 which is a contact point for a shock-absorbing spring 25;
22  sleeve-shaped hammer;
23  receiver for hammer action; 24  return spring;
25  shock-absorbing spring;
26  locking slot (on top of box section 32 to accept locking hook);
27  handle;
28  rod (push rod for return spring)  connected between the shank 21 and the bottom of the return spring 24;
29  trigger and pull cable;
30  safety locking mechanism; 31  chuck;
32  receiver tube (square box section  fixed to the hammer receiver 23);
33  guide bearing fitting into the top of receiver tube 32 for sliding contact with the inside of the shank 21;
34  guide bearing at base of the hammer 22 for sliding on the receiver tube 32; 35  stop screw;
36  screws and stop block;
37  collar for connecting shank 21 to hammer 22;
38  washer fixed to shank 21  for pressing against the shock absorbing spring 25;
39  slot for screw stop.
The sliding hammer unit is stopped from coming apart from the receiver unit 32  23 by the screws 35 in the collar 37  which goes through the slot 39 in the shank 21 and stops when the screw 35 hits the stop"" 36 at the top of the receiver box 32.
A tool comprising the body 1 and a tool head (any of items 3 to 10 for example) is a hammer action tool. It may be used as a fork  spade  chisel  hatchet  or any tool which would benefit from a hammer action. The chuck 31 allows for quick change of tools and will accept all existing "SDS" tools. Items 11 shown Fig. 1 can be attached to the hammer 22 where extra weight is required.
The tubular shank 21 and the hammer 22 are together a hammer weight which is pushed down by the user until it hits the receiver 23/32  driving the tool head. The spring 24 returns the hammer 22 and the shank 21 back up to the start position ready for the next hammer action. The spring 25 takes the shock out of the impact for the user""s hands  as it is between the shank 21 and the hammer 22.
The shank 21 and the hammer 22 slide up and down together on the box-section receiver tube 32. ). The bearing 34 is at the base of the hammer 22 and the bearing 33 is at the top of the receiver tube 32. The sliding action is kept smooth with the two plastics bearings 33 and 34 as these slide on the surfaces of the shank 21 (inside) and the receiver tube 32 (outside
Thus  the tool body 1 comprises two mutually sliding units  namely the receiver 32/23 which may be regarded as fixed for visualisation purposes  and the hammer weight 21/22 unit which slides on the receiver tube 32. These two units are interconnected by the return spring 24  which is anchored to the receiver unit 32/23 at the top of the receiver tube 32 and to the hammer unit 21/22 at the bottom of the rod 28 (fixed by the bolt 30 to the shank 21). The user action of pushing the shank 21 down is against bias of the return spring 24. Upon impact of the hammer 22 with the receiver 23  the shaft 21 continues to slide relative to the hammer 22 within the small extent allowed by the spring 25 for shock absorption. The sequence of links between the receiver 23 and the handle 27 is as follows: receiver 23 and integral receiver tube 32  top of return spring 24  bottom of return spring 24  bottom of rod 28  top of rod 28  shank 21  handle 27. Because this sequence includes the spring  the user""s pressing down of the handle and hence of the hammer is against bias of the return spring 24  causing it to extend. Then  upon impact of the hammer 22 with the receiver 23 the extended return spring pulls the handle and all of the hammer unit back up to be ready for the next stroke.
It will be appreciated that the main role of the rod is simply to extend the return spring 24 so that it can operate to push the hammer back as it contracts again and if the tool is directed upwardly  the return spring also acts to push the tool head up against a work surface. This is particularly suitable for chiselling. Hence the return spring simply tends to push the tool head and the handle apart  thus providing these two important actions at the same time.
The hammer 22 combined with the shank 21 locks down when the locking device 30 comes in contact with the locking slot 26 and is released when the trigger 29 is pulled. Fig. 2(a) shows the locking position and Fig. 2(b) shows the released position. In the locking position the receiver and hammer units are connected together  preventing them from mutually sliding and hence preventing the hammer action.
To use the hammer action  the trigger 29 must be held in the pulled position. When the trigger 29 is released the hammer action will automatically lock for safety. The return spring 24 pressure keeps the catch 30 locked engaging the locking slot 26. This is a safety feature to ensure that the device doesn""t accidentally expand. To unlock  one presses the trigger by compresses the handle to allow the catch 30 clearance from locking slot 26. When compressed  the trigger 29 must then be depressed to release the catch 30. The device will then expand. The trigger 29 must remain depressed for continued hammer action use. Once the trigger 29 is released the catch 30 will automatically lock with the locking slot 26 as the handle is pressed down.
For safety  the handle must be pushed down in order to pull the trigger and release the hammer  because the spring 24 is keeping pressure on the locking device hook.
The tool body 21 provides for very effective action in any situation where a hammer action is desirable. The spring 24 is very effective for returning the hammer to the hammering position  because when one pushes down on the handle  the spring 24 expands and wants to return back to its normal position. The spring 25  importantly  avoids impact shock in the user""s hands. This is achieved by the washer 38 on the shank 21 acting against the spring 25 which acts against the hammer 22. This means that when operating the handle there is no direct contact with the hammer 22. The shock absorbing spring 25 acts as a buffer between the hammer 22 and the shank 21 /handle 27.
As well as lifting the handle up  the spring 24 also pushes the tool head out in the opposite direction. For example  when using the device for chiseling a wall in the overhead position the spring 24 pushes the tool head against the work surface  which means that the chisel point is held in position and one can strike the same point every time. This is particularly advantageous.
Referring to Figs. 7 to 11 an alternative tool body 50 is shown. This differs from that of Figs. 1 to 6 only in minor details. It comprises a handle 51  a shank 52  a hammer 53  a receiver 54  a chuck 55  and a receiver tube 56. There is a return spring 60  a rod 61  an enlarged portion 62 of the rod for engagement with the return spring 24  a shock-absorbing spring 63  and a flange 64 for engaging the shock-absorbing spring 63. A locking mechanism 70 comprises a catch 71 pivoting on a bolt 74 and the catch 71 being biased by a torsion spring 75 having a rear portion 73 pressing against the inner surface of the shank 52 and a bolt 72 for the rod 61. The arrangement of the torsion spring 75 provides very effective locking of the tool body. A bolt 72 connects the rod 61 to the shank 52  bypassing through the shank 52 and an eye in the top of the rod 61. There is a locking mechanism trigger 57  linked to the catch 71 by a cable 58. The top of the spring 60 is connected to the top of the receiver tube 56 by hooks 60(a). The bottom of the spring 60 is secured to the bottom of the rod 61 because is closed over the end of the rod at 60(b).
Instead of a bearing member such as the bearing 33 of Figs. 1 to 6  in this embodiment the top of the receiver tube 56 has a rubber pad on each of the four sides for rubbing against the inside of the shank 52 (best shown in Fig. 8(a)). The manner in which the shock absorption occurs is shown most clearly in Fig. 9  in which it is seen that a flange 64 presses against the shock absorbing spring 63  the lower end of which presses against a ledge within the hammer 53. This provides a very effective shock-absorbing resilient link within the hammer unit.
As shown in Fig. 11 the tool body 50 may be used with a range of tool heads  such as a fork head 100  chisel heads 101. 103  and 104  a hatchet 102  a scraper 105  spade 106  and a rubber head 107 for tapping down slabs. This drawing also shows additional weights 53(a) and 53(b) for the hammer  each having an internal annular male ridge for engaging an annular slot in the hammer.
Fig. 12 shows the tool in use  the user pushing the handle down to cause an impact on the tool head.
Referring to Fig. 13 an alternative chuck  150  is shown. This comprises a square-section tube 151 with a thick wall  providing a socket 152 for receiving a tool head 160. A catch 153 is engaged in a recess 154 and is held in place by a pin 156 extending through both the tube 151 and the catch 153. The catch 153 is biased by a spring 157 to be ready to snap fit into engagement with the tool head 160.
Fig. 14 shows a variation in which a socket 165 has a cylindrical tube 174  with a recess 175 to receive a catch 172 pivoting on a pin 173 and being biased by a spring 171.
The invention is not limited to the embodiments described but may be varied in construction and detail. For example the tool head may be directly secured to or be an integral part of the tool body without a coupler. The return spring may comprise a plurality of individual springs acting in concert  such as concentric coil springs or a combination of a coil spring and a leaf spring for example.

We Claim:
1. A tool body comprising: a handle (27)  a shank (21)  a tool head or a coupler (31) for a tool head  a hammer (21  22) having a hammer part (22) for impact   a receiver (23)  and a spring (24) for biasing the hammer (21  22) to an upper operative position and for biasing the hammer receiver (23) to an outer operative position.
2. A tool body as claimed in claim 1  wherein the return spring has sufficient strength to support the hammer in an operative position without user lifting.
3. A tool body as claimed in claim 1  wherein the return spring has sufficient strength to support the socket or tool head in an operative position when pointed overhead.
4. A tool body as claimed in any preceding claim  wherein the spring (24) is extended in the hammer impact position.
5. A tool body as claimed in claim 4  wherein the spring (24) is located within the shank.
6. A tool body as claimed in any of claims 3 to 5  wherein the receiver (23) comprises a flange for impact with the hammer (22)  and an elongate member (32) protruding upwardly within the shank (21).
7. A tool body as claimed in claim 6  wherein the receiver elongate member (32) is engaged with the return spring (24).
8. A tool body as claimed in claim 7  wherein a top end of the return spring engages the receiver elongate member (32).
9. A tool body as claimed in any of claims 6 to 8  wherein the hammer is connected to the return spring by a rod (28) which is connected to the shank and extends into the receiver elongate member (32).
10. A tool body as claimed in claim 9  wherein the return spring (24) is a coil spring through which the rod (28) extends and a lower end of the return spring (24) is engaged with the rod.
11. A tool body as claimed in claim 10  wherein the return spring is closed over a lower end ofthe rod (28).
12. A tool body as claimed in any preceding claim  further comprising a locking mechanism (30  26) for locking the hammer down.
13. A tool body as claimed in claim 12  wherein the mechanism is operated by pulling a trigger (29) in the handle.
14. A tool body as claimed in either of claims 12 or 13  wherein a biased catch (30) engages in a slot (26) to lock the hammer.
15. A tool body as claimed in any of claims 12 to 14  wherein the locking mechanism has a default locked position.
16. A tool body as claimed in any preceding claim  further comprising a shock-absorbing spring (25).
17. A tool body as claimed in claim 16  wherein the shock-absorbing spring (25) is within the hammer (22).
18. A tool body as claimed in claim 17  wherein the shock absorbing spring extends between the shank (21) and the hammer part (22) for impact with the receiver.
19. A tool body as claimed in claim 18  wherein the hammer part (22) is cylindrical  surrounding the shank.
20. A tool body as claimed in any preceding claim  wherein the hammer (22) is slides on and surrounds an elongate tube (32) secured to the receiver (23).
21. A tool body as claimed in any preceding claim  further comprising means (11) for adding weight to the hammer.
22. A tool body as claimed in claim 21  wherein the weight means comprises cylindrical sectors having features for engagement with the hammer when they surround the hammer.
23. A tool body as claimed in claim 22  wherein the features include a ridge and a groove.
24. A tool body as claimed in any preceding claim  comprising a coupler for a tool head  the coupler comprising a hollow tube having and a catch in a side wall for engaging with a tool head inserted into the tube.
25. A tool body as claimed in claim 24  wherein the tube is shaped to receive a tool head at any of a plurality of orientations.
26. A tool comprising a tool head and a tool body as claimed in any preceding claim.
27. A tool as claimed in claim 26 when dependent of claims 24 or 25  wherein the tool head comprises a shank shaped to fit within said tube and has a recess for engagement with the catch.
28. A tool as claimed in claim 27  wherein the tool head shank has a plurality of recesses for engagement with the catch  to provide different tool head orientations.

Dated this 21st Day of October 2011