US3709305A

US3709305A - Controlled reaction underwater power tool

Info

Publication number: US3709305A
Application number: US00114477A
Authority: US
Inventors: H Morress
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-02-11
Filing date: 1971-02-11
Publication date: 1973-01-09
Anticipated expiration: 1990-01-09

Abstract

Hydraulic media, under pressure is utilized to drive in a torque-free manner, a turbine-type underwater power tool. Torque reaction nozzles are provided on the tool housing to exhaust pressurized liquid in a direction counterclockwise to the torque generated by the tool driving rotor. Means under control of the operator are provided to regulate the amount of pressurized liquid exhausted through the nozzles. A sling is also provided on the tool housing related to a hand grip means at such location as to permit an operator to grip the hand grip while the sling engages the forearm of the operator for suspension of the tool in proper working position.

Description

United States Patent [191 Morress 1 Jan. 9, 1973 [54] CONTROLLED REACTION UNDERWATER POWER TOOL [76] Inventor: Harmon F. Morress, 7412 Kellogg Avenue, Cincinnati, Ohio 45230 [22] Filed: Feb. 11, 1971 21 Appl. No.: 114,477

[52] US. Cl. ..l73/30, 173/159, 173/163, 415/152, 415/503 [51] Int. Cl ..F01d 15/06 [58] Field of Search ..l73/159, 163, 30, 50; 175/6; 415/503, 152

[56] References Cited UNITED STATES PATENTS 3,396,941 8/1968 Crawford ..4l5/503 X 2,763,461 9/1956 Hill ..4l5/152 1,836,597 12/1931 Horman ..173/30 X 2,287,260 6/1942 Luck ..173/50 1,711,193 4/1929 Wunderlich ..415/219 R 10/1967 Nasu et al ..173/159 X 9/1969 Penza ..173/l59 Primary Examiner-Ernest R. Purser Attorney-.1. Warren Kinney, Jr.

[57] ABSTRACT Hydraulic media, under pressure is utilized to drive in a torque-free manner, a turbine-type underwater power tool.

Torque reaction nozzles are provided on the tool housing to exhaust pressurized liquid in a direction counterclockwise to the torque generated by the tool driving rotor. Means under control of the operator are provided to regulate the amount of pressurized liquid exhausted through the nozzles. A sling is also provided on the tool housing related to a hand grip means at such location as to permit an operator to grip the hand grip while the sling engages the forearm of the operator for suspension of the tool in proper working position.

22 Claims, 10 Drawing Figures PATENTEDJAH 9191s 3.709.305

FIG-4 INVENTOR HARMON E MORRESS PATENTEDJAH 9 I973 3,709 .305

SHEET 2 BF 5 INVENTOR HARMON F. MORRESS PATENTED JAN 9 I973 SHEET 3 UF 5 nvvsmron HARMON F. MORRESS AT R EY PATENTEDJAN 9 I975 SHEET 0F 5 2/4 wvsuron HARMON F. MORRESS FIG-9 PATENTEUJAN 9 I975 SHEET 5 OF 5 Rum NNM

CONTROLLED REACTION UNDERWATER POWER TOOL BACKGROUND OF THE INVENTION In recent years there has been a tremendous growth of underwater or submarine commercial work which has presented an ever increasing demand for specialized tools for use in underwater environment. Usually, such underwater tools have been operated pneumatically or electrically, and whereas said tools have, within limits, operated successfully, their use has been seriously impeded due to the fact that either compressed air or electricity must be brought to the tool at the location of the underwater work. The pneumatic or electrically operated underwater tools have not only been difficult to handle by an operator, they have also been characterized by low power and danger to the operator, particularly when electricity is used as the motivating media. The present invention is directed to a hydraulically operated underwater tool which is capable of efficient operation at great depths and which is characterized by a substantially torque-free reaction, which reaction is selectively adjustable and controllable by the operator using the tool in the performance of underwater work.

SUMMARY OF THE INVENTION The general object of the invention is to provide a most efficient means of performing underwater work, and one of the specific advantages of the present invention is that it utilizes a tool which is torque free and therefore requires little or no effort on the part of the operator to hold a tool in the correct operating position.

Another object of the invention is the provision of a tool which includes means for enabling it to be selectively adjusted, under water, by an operator, whereby to provide its own thrust in whatever direction is required, in order to more effectively accomplish the work being done.

Still another object of the invention is to provide a tool having the hereinabove characteristics which tends to maintain correct linearity when driven at high speeds due to the gyroscopic effect of the drive rotor.

Still another object of the invention is to provide a tool which will operate with equal speed and efficienty in forward and reverse directions.

Another importznt advantage is that the tool of the present invention is water lubricated by the media in which it is used and therefore requires no other lubricant of any kind whatsoever.

Still another object of the invention is to provide an underwater hydraulically operated tool which is designed in such a manner as to be conveniently sup ported by an operator and wherein the control means are not only within easy reach but comprise part of the tool support means normally grasped by an operator in using the tool.

DESCRIPTION OF THE INVENTION These and other objects are attained by the means described herein and as disclosed in the accompanying drawings in which:

FIG. 1 is a perspective view of an underwater or submarine tool embodying the teachings of the present invention.

FIG. 2 is a view similar to FIG. 1 with the elements comprising the driving mechanism shown in disassembled or exploded relationship.

FIG. 3 is an end view of the rotor disc, comprising part of the drive assembly.

FIG. 4 is a sectional view taken on line 4-4 of FIG. 3.

FIG. 5 is a perspective view of the FIG. 4 element shown in association with other elements which cooperate therewith for enabling an operator to change the direction of rotation of the drive rotor.

FIG. 6 is a perspective, exploded view of the housing elements, including means for regulating torque reaction forces.

FIG. 7 is a perspective, exploded view on an enlarged scale showinga manual control mechanism comprising a detail of the present invention.

FIG. 8 is a perspective view illustrating a waterhammer dampening means.

FIG. 9 is a perspective view of a modification of the device of FIG. 1, embodying the present invention.

FIG. 10 is a side view of a second modification of the tool of the present invention.

With particular reference to FIG. 1, the numeral 20 denotes generally a tool embodying the teachings of the present invention and wherein the numeral 22 denotes a hose or other suitable conduit through which a fluid media, such as water, is introduced under pressure as by means ofa pump or the like, not illustrated.

Conduit 22 may be secured by means of a clamp 24 to one member 26 of a swivel coupling which includes a second member 28 the discharge end of which may be secured by means of a clamp or connector denoted generally by the numeral 30, to the inlet end of the tool. At its forward end, the tool may carry an arbor 31 to which maybe secured a suitable chuck or holder for any conventional form of bit, cutter, or impact element, that may be required during use of the tool. Such a chuck or holder is shown at C upon FIG. 10, carrying a common form of drill it 32 by way of example. More broadly considered, element 32 is regarded as a workengaging implement of any suitable type or kind, and may be applied to the tool of FIG. 1.

With further reference to FIGS. 1 and 2, the numeral 34 indicates a valve actuator whereby pressured fluid from hose 22 may be directed to a rotor 36, which rotates arbor 31 and the work engaging implement thereto attached, As shown in FIGS. 1 and 2 by way of example, actuator 34 is normally elevated in closed valve position, but may be manually depressed by the hand or thumb of a diver-operator to initiate actuation of the rotor and implement-carrying arbor 31. Ordinarily, the divers fingers will grasp the hand-hold 38, while his thumb depresses the valve actuator 34 as required.

In a preferred form of the invention, there is provided an upstanding sling or loop member 40, made preferably of a soft flexible material such as leather, rubber, plastic, or the equivalent, through which the operator may thrust his fore-arm or some portion thereof, (see FIG. 10), to support and guide the tool while drilling, cutting, shaping or otherwise operating upon a workpiece. The sling may be properly located to achieve balance and maneuverability of the tool to best advantage; and the distance from the sling to handle 38 and actuator 34 may be greater than depicted by FIG.

1, if desired. A fixed bracket or guard 42 may support the valve actuator and handle 38.

In the example illustrated by FIGS. 1 through 8, the primary body member of the tool comprises an elongate rigid tube 44 (FIG. 8), adapted for connection with

swivel coupler

26, 28 according to FIG. 8. Tube 44 preferably is provided with a spring loaded pressure relief valve of any appropriate type. As shown, a typical relief valve comprises one or more

arcuate plates

46, 46 apertured for mounting upon a stud 49 fixed to tube 44, the plates normally being held against the

relief openings

48, 48 by spring means 50,52, to normally preclude loss of pressured fluid through

openings

48, 48. In the event of water hammer surges occasioned by sudden release of valve control member 34, the relief valve will cushion the resulting shock.

The inner end of tube 44 carries a flange 54 which is bolted to a throttle valve housing 56 containing a butterfly valve 58 which is normally closed. Valve 58 can be opened by depressing the actuator 34, thereby to permit a flow of pressured fluid through tube 44 and valve housing 56. This flow results in turning the rotor 36, as will be explained.

Throttle valve housing 56 comprises an upper sector 60 and a lower sector 62 adapted to embrace a tubular valve cage or seat element 64, the latter being fixed to body tube 44 at flange 54 in coaxial alignment therewith.

Parts

60 and 62 are clamped about element 64 by means of screws 66. Part 60 is provided with an internally threaded opening 68 for reception of a threaded end 70 on handle 38.

Handle 38 is secured to bracket 42 by screws 72 which flank a longitudinal bore 74 of the handle. Bore 74 loosely accommodates a tubular actuator stem 76 having formed in its side wall a pair of opposed

spiral slots

78, 78, said slots being receptive of a fixed pin 80 which is anchored in a transverse drill hole 82 of handle 38. Pin 80 and slots 78 enforce rotation of stem 76 whenever the stem is axially moved, rotation of the stem being limited to 90 degrees by the length of

slots

78, 78. Actuator head 34 is pivoted atop the stem 76 by means of a screw 84 threaded into the upper open end of the stem. A plug 86 is threaded into top opening 88 of head 34, to lock the screw 84.

The open lower end of stem 76 is loosely receptive of a pin 92 which slides longitudinally therein, said pin being rendered non-rotatable within the stem bore by the action of a transverse pintle 94 of pin 92 traveling in a side wall slot 96 of stem 76. Pin 92 has a lower end normally anchored in a top opening 98 of valving member 58, by means of a pintle 100 which enters

transverse openings

102 and 104 respectively, of the valving member 58 and pin 92. Thus, reciprocatory movement of actuator stem 76 is translated into rotary movement of valving member 58 limited to 90 degrees by

spiral slots

78, 78. A spring 106 which acts upon the lower end of stem 76, constantly urges the stem toward its upper limit of travel, at which limit the valving member 58 is seated in the closed position shown, FIG. 7.

Reverting to FIG. 2, the numeral 108 indicates a bearing tube which constitutes a fixed axial extension of primary body tube 44. Bearing tube 108 is nonrotatable, and extends forwardly of throttle vale housing 56.

A turbine housing 110 surrounds bearing tube 108 and is concentric thereto. Housing 110 is fixed to either the primary body tube 44 or the throttle valve housing 56, so as to be a stationary part of the assembly. In accordance with FIGS. 1 through 6, the turbine housing is bell shaped and comprises a conical wall 112, a narrow cylindrical wall portion 114, and a mounting flange 116 adapted for bolting to housing 56 or body tube 44. A flange 118 on the wall portion 114 provides means to support a forward cover member 120.

The enlarged cylindrical wall portion 114 is provided with a multiplicity of exhaust apertures 122 disposed about the periphery of said wall portion. A control band 124 similarly apertured as at 126, surrounds the wall portion 114 and may be rotated upon a common axis to place the apertures 126 thereof in registry or out of registry with the wall apertures 122, thereby to regulate flow of fluid outwardly through the wall apertures. Band 124 may be rotationally adjusted by means of a handle 128, and the extent of rotation may be limited by a stationary pin 130 (FIG. 6) working in a slot 132 of band 124. The band may be adjusted to close all the housing apertures 122, if desired.

In addition to the exhaust apertures 122, housing 110 is provided with one or more other exhaust apertures 134 each terminating in an adjustable nozzle 136. By preference, two such nozzles and associated apertures are provided. The apertures 134 and nozzles 136 preferably are carried by the conical wall 112 of the turbine housing, and the nozzle mounts 138 are swivel or rotational mounts which permit directing the nozzle discharge at various angles to the major axis of the tool. In support of this purpose, the nozzles may be bent or curved as shown.

In the light of the foregoing explanation, it will be understood that a diver using the tool under water may twist the nozzles 136 into a position such as that suggested by FIG. 1, for emitting a jet or stream of water rearwardly in aid of a forward propulsion of the tool bit against a workpiece; or if desired, the nozzles may be adjusted to emit jets more or less tangential to housing 110, with a tendency to induce bodily rotation of the tool about its major axis in a direction counter to the torque produced by contact of a rotary implement acting upon a workpiece. The tool as a whole may thereby be rendered torque-free in practice, to facilitate handling and expedite the work performed.

The nozzles preferably are adjustable about their mounts 138 over a range of 360, so that forward and rearward propulsion, and/or torque reaction forces may be selected by the operator at his discretion. As is evident, the force of the jets emitted by the nozzles may be increased or decreased by closing or opening to various degrees the radial exhaust apertures 122 under the control of control band 124.

For activating the bit arbor 31, there is provided the rotor 36 previously mentioned. Rotor 36 includes a hub 140 having an inner hollow cylindrical end portion 142, and an outer end portion 144 having an axial bore 146. The inner end portion 142 surrounds and rotates upon bearing tube 108, the bearing surfaces being lubricated solely by water fed into housing 110 through said beara ing tube.

A disc 148 fixed upon hub 140, is provided with one pair of

passageways

150, 150 extending radially from the bore of end portion 142 and terminating in

rotor nozzles

152, 152. A second pair of

passageways

154, 154 extend radially from the bore of end portion 142, and terminate in

rotor nozzles

156, 156. Nozzles 156 are arranged to emit a stream of water tangentially of the disc periphery, in a direction such as to produce counterclockwise rotation of the rotor, viewed from the front of the apparatus. On the other hand, nozzles 150 are arranged to emit a tangential stream in a direction such as to produce clockwise rotation of the rotor.

Means is provided for the introduction of pressured water selectively to

passageways

150, 150, or to

passageways

154, 154. Such means may comprise a selector valve 158 (FIG. 5), having a solid shaft 160 provided at one end with a valve head 162. The valve head consists of a hollow cup fixedly mounted upon shaft 160, said cup being open at one end and having a cylindrical side wall provided with diametrically opposed port openings I64, 164 in communication with the interior of the cup.

Valve 158 is supported loosely within hub 140, with its shaft 160 resting in hub bore 146. By rotating the valve 158 90, its

ports

164, 164 may be placed in register with either pair of

passageways

150, 150, or 154, 154.

Valve shaft 160 at its free end is transversely drilled and tapped as at 166 to accommodate the screwthreaded ends of

screws

168, 168 which pass loosely through 90-

degree radial slots

170, 170 in hub portion 144. These screws, in cooperation with

slot

170, 170, limit rotation of valve head 162 to ensure registry of

ports

164, 164 with the

passageways

150, 150, or with the

passageways

154, 154, depending upon the direction of rotation imparted to shaft 160. A cylindrical external collar 172 loosely surrounding a portion of the rotor hub, and slotted at 174 in correspondency with the slots 170, provides a simple hand piece and lock whereby the diver may manipulate valve 158 to reverse rotation of arbor 31 and a bit carried thereby.

The cylindrical outer end portion 144 of hub 140 constitutes a journal rotatable in a bearing 176 fixed upon cover member 120, and is water-lubricated from the interior of housing 110. Cover member 120 may be secured to housing flange 118 by a series of screws or equivalent fasteners 178, FIG. 1.

The modification illustrated by FIG. 9 suggests the use of

angular torque nozzles

236, 236 mounted for manipulation in the manner of nozzles 136, but having no connection with the interior of rotor housing 210. The primary body tube 244, which corresponds to tube 44 of FIG. 8, supplies pressured water to the housing 210 and the rotor therein, according to previous explanation; but the

nozzles

236, 236 are supplied from body tube 244 through separate

external branch pipes

212 and 214 which connect with the swivel mounts 216, 216 of the nozzles. Flow of pressured water through the branch pipes and nozzles may be controlled by means of separate valves associated with said branch pipes and regulated by means of valve operators or hand wheels 218.

In FIG. 9 the throttle valve housing is denoted 256, and may incorporate a throttle valve having an actuator 34 corresponding to the throttle valve and actuator of FIG. 7. With the use of external branch supply pipes and control valves according to FIG. 9, it is unnecessary to control the rotor exhaust through apertures 222 of housing 210. Housing 210 will of course carry a rotary arbor and a bit holder in the manner of FIG. 10, and the .tool may also incorporate a sling such as is depicted at 40 of FIG. 1.

In the FIG. 10 modification, the tool is distinguished by the use of a large slow speed rotor in housing 310, and chuck arbors 331 at opposite ends of the tool. The input hose 322 feeds pressured water to the tool at one side rather than at the rear thereof. A sling 340 is provided, corresponding to the sling 40 of FIG. 1, and the tool may be guided also by means of a handle 338. One or more torque reaction nozzles 336 perform as do the nozzles of FIG. 1, to render the tool torque-free and thereby facilitate and expedite the underwater work to be performed.

In FIG. 10 as well as in the other forms of the invention, the arbor carrying the chuck may be rendered rapidly reciprocative by incorporating a conventional impact unit well known in the art, so that the tool may be used for cutting rivets or penetrating a workpiece by impact or hammering impulses. The impact unit mentioned is available in various forms, and includes means to convert rotary movement of the rotor-driven arbor to a rapid succession of hammer blows or impacts deliverable to the bit or cutting implement.

OPERATION OF THE DEVICE To prepare the device of the invention for use, a chuck and a suitable bit are applied to the arbor 31, and connection is made to the hose or conduit 22 which delivers water under pressure to the primary body member 44. The device may then be lowered to the underwater work site, where the diver-operator will insert his forearm into sling 40 and grasp the handle 38 for guiding the tool into desired position upon the workpiece.

By depressing the throttle valve actuator 34, water under pressure is directed into rotor 36 and housing 110, the rotor serving to actuate the bit or cutting implement carried by the arbor. As the bit or implement engages the work, torque force may be generated tending to bodily rotate the tool in the hands of the operator. 'Io negate the torque so generated, the operator may close or partly close the housing exhaust apertures 122 by adjustably rotating the control band 124, thereby to induce emission of a jet stream of water through

nozzles

136, 136; then by adjusting the angularity of jet discharge at the nozzles, the operator may counter balance the bit torque so as to render the tool torque-free in operation.

By adjusting the nozzle angularity, and the position of control band 124 to establish a desired jet force at the nozzles, the operator can not only overcome the driving torque, but can also cause the nozzle jets to propel the tool bodily toward the workpiece, causing turn exhausts to the body of water supplying the pump. There is n hazardous electric current needed at the too].

When necessary or desirable, the operator may make an easy underwater adjustment at collar 172, to effect a reverse rotation of rotor 36 and the bit driven thereby.

What is claimed is:

1. A hydraulically operated underwater power tool, which comprises in combination: an elongate housing having a major axis and opposite end portions; a rotor within the housing, nd means supporting the rotor for rotation on an axis substantially parallel to said housing axis; hydraulic means for rotating said rotor, including a pressured liquid supply means; means driven by said rotor for actuating a work-engaging implement; torque reaction means carried by the housing, to exhaust pressured liquid in a direction counter to the torque generated by said rotor and/or said implement in contact with a workpiece, for substantially stabilizing said tool against forces tending to rotate the tool housing relative to the workpiece, hand grip means on the tool housing to be grasped by the hand of an operator, and a sling secured to said housing adjacent said hand grip means in a position to engage the forearm of an operator and hold the tool substantially parallel to the forearm of an operator while the hand of the operator is grasping the hand grip means to enable the operator to suspend the tool at work piece-engaging position.

2. The tool as defined by claim 1, wherein said rotor is in the form of a turbine rotor in that it discharges pressured liquid from the periphery thereof substantially tangentially of said periphery.

3. The tool as defined by claim 1, wherein said liquid supply means includes the water in which the underwater power tool is immersed while operating.

4. The tool as defined by claim 1, wherein is included means for reversing the direction of rotation of said workpiece engaging implement.

5. The tool as defined by claim 1, wherein is included means for regulating the speed of rotation of said rotor and of said work-engaging implement.

6. The tool as defined by claim 1, wherein is included means under the control of an operator, for regulating the torque reaction force while the tool is submerged.

7. The tool as defined by claim 2, wherein is included means for reversing the direction of rotation of said workpiece engaging implement.

8. A hydraulically operated underwater power tool, which comprises in combination: an elongate housing having a major axis and opposite end portions; a rotor within the housing, and means supporting the rotor for rotation on an axis substantially parallel to said housing axis; hydraulic means for rotating said rotor, including a pressured liquid supply means; means driven by said rotor for actuating a work-engaging implement; torque reaction means carried by the housing, to exhaust pressured liquid in a direction counter to the torque generated by said rotor and/or said implement in contact with a workpiece, for substantially stabilizing said tool against forces tending to rotate the tool housing relative to the workpiece, said torque reaction means comprising at least one nozzle means carried by said housing, for discharging liquid from said pressured supply means into the underwater environment of the power tool, at an angle to said housing axis.

9. The tool as defined by claim 8, wherein is included means for regulating the flow of pressured liquid through said torque reaction means.

10. The tool as defined by claim 8, wherein said nozzle is operator-adjustable to alter the angularity of liquid discharge relative to said housing axis.

11. The tool as defined by claim 10, wherein the nozzle is adjustable to discharge liquid in a direction such as to impel the work-engaging implement toward or from the workpiece.

12. The tool as defined by claim 8, including conduit means remote from said rotor for supplying pressured liquid to'said nozzle means.

13. The tool as defined by claim 12, wherein said conduit means is located externally of said housing, and said conduit means includes a valve to regulate the delivery of pressured fluid to said nozzle means.

14. The tool as defined by claim 13, wherein is included a second valve independently operative to regulate the delivery of pressured fluid to said rotor, for varying the rate of rotor rotation.

15. The tool as defined by claim 12, wherein is included a manifold located between said rotor and said liquid supply means, for feeding pressured liquid to said.

conduit means.

16. A hydraulically operated underwater power tool, which comprises in combination: an elongate housing having a major axis and opposite end portions; a rotor within the housing, and means supporting the rotor for rotation on an axis substantially parallel to said housing axis; hydraulic means for rotating said rotor, including a pressured liquid supply means; means driven by said rotor for actuating a work-engaging implement; torque reaction means carried by the housing, to exhaust pressured liquid in a direction counter to the torque generated by said rotor and/or said implement in contact with a workpiece for substantially stabilizing said tool against forces tending to rotate the tool housing relative to the workpiece, and means under the control of an operator, for regulating the amount of pressured liquid exhausted through said torque reaction means to regulate the torque reaction force while the tool is submerged.

17. The tool as defined by claim 16, wherein is included a sling supported by said housing to accomrotor-driven means is adapted to carry two work-engaging implements.

21. The tool as defined by claim 20, wherein the means last mentioned comprises a shaft having opposite ends extending in opposite directions from said housing, said shaft ends each including means to support a work-engaging implement.

22. The tool as defined by claim 21, wherein is included a sling supported by'saidhousing to accommodate the forearm of an operator in suspending the

Claims

1. A hydraulically operated underwater power tool, which comprises in combination: an elongate housing having a major axis and opposite end portions; a rotor within the housing, nd means supporting the rotor for rotation on an axis substantially parallel to said housing axis; hydraulic means for rotating said rotor, including a pressured liquid supply means; means driven by said rotor for actuating a work-engaging implement; torque reaction means carried by the housing, to exhaust pressured liquid in a direction counter to the torque generated by said rotor and/or said implement in contact with a workpiece, for substantially stabilizing said tool against forces tending to rotate the tool housing relative to the workpiece, hand grip means on the tool housing to be grasped by the hand of an operator, and a sling secured to said housing adjacent said hand grip means in a position to engage the forearm of an operator and hold the tool substantially parallel to the forearm of an operator while the hand of the operator is grasping the hand grip means to enable the operator to suspend the tool at work pieceengaging position.

12. The tool as defined by claim 8, including conduit means remote from said rotor for supplying pressured liquid to said nozzle means.

15. The tool as defined by claim 12, wherein is included a manifold located between said rotor and said liquid supply means, for feeding pressured liquid to said conduit means.

17. The tool as defined by claim 16, wherein is included a sling supported by said housing to accommodate the forearm of an operator in suspending the tool at work piece-engaging position.

18. The tool as defined by claim 17, wherein is included a manually operative valve in proximity to said sling, for controlling flow of pressured liquid to said rotor.

19. The tool as defined by claim 16, wherein is included a manually operative valve for controlling flow of pressured liquid through said hydraulic means.

20. The tool as defined by claim 16, wherein said rotor-driven means is adapted to carry two work-engaging implements.

22. The tool as defined by claim 21, wherein is included a sling supported by said housing to accommodate the forearm of an operator in suspending the tool at workpiece-engaging position; and a tool guiding handle supported by the housing adjacent to said sling.