US3678524A

US3678524A - Heavy duty vacuum cleaner

Info

Publication number: US3678524A
Application number: US20909A
Authority: US
Inventors: Wilfred C Nise; Dale E Lowder
Original assignee: Studebaker Corp
Current assignee: Cooper Industries LLC; Studebaker Corp
Priority date: 1970-03-19
Filing date: 1970-03-19
Publication date: 1972-07-25
Anticipated expiration: 1989-07-25
Also published as: CA923260A

Abstract

A first frame is supported by wheels and a second frame is pivotally connected at one of its ends to the first frame on the axis of rotation of those wheels. Also secured to the first frame are a rotating horizontal-axis brush and other conventional features of a sweeper with vacuum. The free end of the second frame is supported by casters. Wedges are mounted at either side and on the top of the free end of the second frame. A threaded shaft is mounted on the first frame such that it passes over those wedges and carries blocks which engage the inclined surface of the wedges. The blocks travel across these inclined surfaces when the shaft is rotated, since they are restrained by channels from rotation with the shaft. The travel of the blocks adjusts the spacing between the first and second frames to raise and lower the first frame and its equipment with respect to the surface being treated while the angular relationship between the second frame and the floor remains substantially unchanged.

Description

United States Patent Nise et al.

11 1 3,678,524 1451 July 25,1972

[54] HEAVY DUTY VACUUM CLEANER [72] Inventors: Wilfred C. Nise, Spring Lake; Dale E.

Lowder, Muskegon, both of Mich.

Clark Floor Machine Company Division of Studebaker Corporation, Muskegon, Mich.

[22] Filed: March 19, 1970 [21] App]. No.: 20,909

[73] Assignee:

[52] U.S.Cl ..15/49, 15/351, 15/354 [51] Int. Cl ..A47l 11/00, A471 5/34 [58] Field of Search ..15/49-52, 98, 99,

2,691,791 10/1954 Humphrey ..15/354 UX Primary Examiner-Leon G. Machllin Attorney-Price, Heneveld, Huizenga & Cooper [57] ABSTRACT A first frame is supported by wheels and a second frame is pivotally connected at one of its ends to the first frame on the axis of rotation of those wheels. Also secured to the first frame are a rotating horizontal-axis brush and other conventional features of a sweeper with vacuum. The free end of the second frame is supported by casters. Wedges are mounted at either side and on the top of the free end of the second frame. A threaded shaft is mounted on the first frame such that it passes over those wedges and carries blocks which engage the inclined surface of the wedges. The blocks travel across these inclined surfaces when the shaft is rotated, since they are restrained by channels from rotation with the shaft. The travel of the blocks adjusts the spacing between the first and second frames to raise and lower the first frame and its equipment with respect to the surface being treated while the angular relationship between the second frame and the floor remains substantially unchanged.

17 Claims, 6 Drawing Figures HEAVY DUTY VACUUM CLEANER BACKGROUND This invention relates to an improvement in means for controlling the spacing between a floor treating element and the floor.

Almost any type of cleaning machine utilizes a floor treating element such as a brush or its equivalent in performing its function. Examples include floor scrubbers, polishers,

types of machines.

In controlling the relative elevation of the brush means, it is always desirable that the degree of contact between the brush means and the surface being cleaned remain constant throughout the length of the brush means. Most elevation control mechanisms require the use of frames which are very sturdy from side to side in order to achieve this uniform contact. This is because the control is located on one side of the machine and its action must be transmitted to the other side by the sturdy frame. If the frames are structurally inadequate, the degree of contact will be irregular and may even vary during operation if the structure of the frame permits it to warp or to rock on the control mechanism.

Many elevation control mechanisms are not suitable for use on machines where it is desireable to use casters as an integral part of the control mechanism. Such mechanisms do not allow the caster pintles to remain perpendicular to the surface being cleaned. The result is that the degree of contact between the brush and the surface being cleaned varies, depending on whether the machine is being moved forwardly or rearwardly.

Other mechanisms are designed with the control activation element, such as a knob or lever, located at the rear of the machine. These mechanisms are unacceptable for use in a variety of machines such as those having large bulky bags or handles. Furthermore, rear activated control mechanisms frequently necessitate the use of very sturdy and heavy control frames.

' SUMMARY OF THE INVENTION This invention comprises generally a first frame means and a second frame means pivotally connected to it. A brush means is mounted on the first frame means at some distance from the pivot axis between the two frame means. A support means is mounted on the second frame means, also at some distance from the aforementioned pivot axis. There is a cam means between said first and second frame means located at a distance from the aforementioned pivot axis. An activating means is provided for activating said cam means whereby a variation can be achieved in the angular relationship between the first and second frame means.

Thus, one object of this invention is to provide an elevation control mechanism which is simple, effective and economical in construction.

Another object is to provide a mechanism which effectuates a uniform degree of contact between the brush means and the surface being cleaned, without the necessity of using a very heavy-duty frame.

This invention also allows one to use casters to support the second frame means since it keeps the caster pintles generally perpendicular to the surface being cleaned.

This invention further provides a mechanism which is adaptable for use with a side-mounted activating means, such as a knob mounted on the side of the machine rather than on its rear. Further,the cam and wedge system is utilized with a minimum of force applied to the actuation knob or handle.

Finally, the use of elaborate lever mechanisms and the like are eliminated.

BRIEF DESCRIPTION OF THE DRAWINGS These andother objects and advantages of the invention can be visualized by reference to the appended drawings wherein:

FIG. I shows a bottom perspective view of a heavy-duty sweeper;

FIG. 2 shows aside view of a heavy-duty sweeper with a portion being broken away;

FIG. 3 shows a perspective of the machine with the front being broken away along Ill-Ill of FIG. 2,- and with the vacuum hose and impeller housing not shown;

FIG. 4 shows a fragmentary elevation taken along Ill-Ill of FIG. 2;

" FIG. 5 shows an elevation of an arm end and wedge taken on line V--V of FIG. 4; and

FIG. 6 shows an elevation of an arm end, wedgeand cam taken on line VI-VI of FIG. 4.

PREFERRED EMBODIMENTS The invention is here embodied in a heavy-duty sweeper with vacuum pick-up. Besides the conventional elements found in such an apparatus, it includes a first frame 10, (FIG. 1) a second frame 20 pivotally secured thereon, a pair of wedges 30 on the free end of second frame 20, threaded shaft 40 onfirst frame 10, a pair of blocks or cams 50 (FIG. 2) on threaded shaft 40 and a pair of channel members 60 on first frame 10.

First frame 10 includes a platform 11, having sides l2-and back 13 both depending downwardly therefrom (FIGS. 1, 2 and 3). The bottom edges of sides 12 slope upwardly from front to back. Extending across the front of frame 10 is a housing 14 in which a brush 2 is mounted]. Frame 10 can readily be fabricated in any suitable manner such as being a casting or formed from sheet material.

Rotatably attached to each side 12 of frame 10, near the rear thereof, is a large wheel 3 (FIGS. 1 and 3). Each axle 3a of each of said wheels 3 is secured to a side 12 and extends inwardly therefrom. It is sufficiently long that it extends through the hub of wheel 3and provides a stub shaft upon which second frame 20 is rotatably mounted.

Mounted on platform 11 are other conventional elements such as a motor 4, an impeller housing 5 and a vacuum hose 6 (FIGS. 1 and 2). These elements are enclosed by a cover 7. A handle 8 is secured to the rear of frame 10 and extends upwardly therefrom. .Mounted on handle 8 is a bag 9 which receives litter from impeller in housing 5. All of these elements (except the mounting of the second frame) cooperate in a conventional fashion and do not of themselves form of this invention.

Second frame 20 (FIGS. 1 and 2) comprises a U-shaped member including a pair of arms 21 and a cross piece 22. Each arm 21 is U-shaped in cross section. The ends of the arms 21 are joined through cross piece 22 which is rigidly secured to both arms as by bolting or welding. A caster 23 is connected to each arm 21 adjacent the cross piece 22. The non-joined ends of arms 21 are each pivotally mounted on the inwardly extending stub shaft of axle 3a.

Wedge members 30 can best be seen in FIGS. 3, 4 and 5. Each includes an attachment flange 31 (FIG. 5) whereby it is rigidly secured to the end of an arm. 21 adjacent cross piece 22. A wall 32 extends upwardlyfrom attachment flange 31 at right angles thereto and is triangular inconfiguration (FIGS. 3 and 4). Then a flange or ramp 33,. comprising an inclined plane extends outwardly from wall 32 at right angles thereto. Ramp 33 has an open ended slot 34 in its uppermost end to provide clearance for the hereinafter described shaft 40.

The threaded shaft 40, shown best in FIGS. 1, 3 and 4 passes through the left wall 12 of frame 10,. as viewed in FIGS. 1, 2 and 3. Shaft 40 passes over the wedges 30 mounted on the a part ends of arms 21. Knob 42 is fastened on that end of shaft 40 which is outside wall 12 and a washer is fixed to shaft 40 just inside of wall 12. In this fashion, shaft 40 is fixed against axial movement. The opposite end of shaft 40 is rotatably mounted in bracket 41 which is integrally secured to the underside of platform 11, near the right wall 12 of frame 10.

Each of the two blocks 50 includes two flat sides 53, two ends 54, a generally flat top 55 and a rounded nose portion 52 (FIGS. 3, 4 and 6). A threaded opening 51 passes through block 50 between ends 54, whereby two such blocks 50 are threaded onto shaft 40. The blocks 50 are free to travel over the surface of ramp 33. The travel of right block 50 is limited by bracket 41 on one side and by a cotter key 43 or equivalent stop on the other side. The travel of left block 50 is limited by cotter keys 43 or equivalent stops located on either side thereof on shaft 40.

Each of the two channels 60 includes a top 61 and side walls 62 (FIG. 6). Each channel 60 is approximately equal in length to the distance which a block 50 is free to travel. Each channel 60 is integrally mounted to the underside of platform 11 of frame as by welding top 61 thereto. Each channel 60 is located such that its side walls 62 embrace a block 50. Thus, each side wall 62 is located closely adjacent a side 53 of each block 50, such that each block 50 is restricted against rotation when shaft 40 is rotated. Rounded nose 52 of each block 50 thus always stays in contact with a ramp 33 of wedge 30.

OPERATION Thus, both first frame 10 and second frame are supported at their back ends by the large wheels 3. In effect, they are pivotally joined together through the axles 3a of wheels 3. The front end of second frame 20 is supported by casters 23. The front end of first frame 10 is supported by the front end of second frame 20 through the blocks 50 and wedges 30. The blocks 50 and wedges 30 form a cam means between first frame 10 and second frame 20 whereby the angle between first frame 10 and second frame 20 can be increased or decreased. Since the orientation of second frame 20 with respect to the surface being cleaned remains constant, an increase in the aforesaid angle will raise the front of first frame 10 and accordingly, brush 2 which is located on the front of first frame 10. Similarly, a decrease in the aforesaid angle will lower brush 2. More specifically, the rounded nose S2 of each block 50 engages ramp 33 of a wedge member 30. When knob 42 is turned, shaft 40 is rotated. However, it is fixed against axial movement. When shaft 40 rotates, each block 50 is held against rotation by the side walls 62 of each channel member 60. Therefore, both blocks to move either simultaneously the same distance laterally of the machine, left or right, depending upon the direction the shaft 40 is rotated. As the blocks 50 move, they slide along ramps 33 of their respective wedges 30. Because the noses 52 are rounded, friction between the blocks 50 and the wedges 30 is minimized.

As blocks 50 are moved towards the uppermost ends of ramps 33, second frame 20 is pivoted about its pivot axis, and the distance between the front of first frame 10 and the free end of second frame 20 is increased. Since second frame 20 is supported at one end on the axles 3a of wheels 3, and at the other end on casters 23, the orientation of second frame 20 with respect to the surface being cleaned remains constant. Consequently the distance between brush 2, which is located at the front of frame 10, ahead of frame 20 and at a rather substantial distance from the pivot axis between first frame 10 and second frame 20, and the surface being cleaned will be increased.

As blocks 50 are moved towards the lowermost ends of wedges 30, the distance between the front of first frame 10 and second frame 20 decreases and consequently brush 2 moves closer to the surface being cleaned. In order to eliminate the need for blocks 50 having substantial distance between their tops 55 and their rounded noses 52, notches 34 are cut into the uppermost ends of ramps 33 such that shaft 40 can settle into those notches 34 without engaging the wedges 30 when the blocks 50 are located at the lower ends of the ramps 33.

The mounting of one cam means, Le. a block 50 and wedge 30, on the left side of the machine, and another cam means located on the right side of the machine insures uniform contact between the entire length of brush 2 and the surface being cleaned, regardless of the relative height of brush 2 with respect to the surface being cleaned. Blocks 50 are adjusted initially on shaft 40 such that the distance between the

frames

10 and 20 is constant throughout the width of frame 20. In effect then, the weight of first frame 10 is supported at two points, one on either side of its center of gravity. These two points are substantially spaced from each other. This insures uniform contact between brush 2 and the surface being cleaned.

As previously pointed out, the orientation of arms 21 with respect to the surface being cleaned remains constant, regardless of the relative positions of cams 50 with respect to wedges 30. Also, the pintles of casters 23 are mounted vertically in arms 21. This insures that the height of brush 2 with respect to the surface being cleaned will be constant regardless of whether the cleaner 1 is being moved forwardly or rearwardly. If the angular relationship of arms 21 changed with changes in the distance between the free ends of

frames

10 and 20, then the pintles of casters 23 would not necessarily remain vertically oriented. Consequently, the distance between the free end of second frame 20 and the surface being cleaned would vary, depending on whether the cleaner was being moved forwardly or rearwardly. correspondingly, the elevation of the front frame 10, and of brush 2, would vary depending on the direction of travel.

Thus, it is preferable that the pivoted ends of arms 21 be pivoted on the axis of rotation of wheels 3. However, this is not absolutely necessary, provided that arms 21 are sufficiently long that the change in orientation of the pintles of casters 23 varies only slightly with changes in the respective positions of blocks 50 and wedges 30. If on the other hand, the arms 21 are short, then the angular orientation of arms 21 with respect to the surface being cleaned will vary too greatly with changes in the respective positions of blocks 50 and wedges 30.

Thus, it can be seen that this invention provides a unique means for controlling the degree of elevation of a brush from the surface being cleaned. In addition, it teaches a means whereby the degree of contact between that brush and the surface being cleaned remains constant throughout the length of the brush. Furthermore, the degree of contact between the brush and the surface being cleaned remains constant regardless of the direction in which the cleaner is traveling.

Furthermore, these ends are achieved without the need for heavy-duty frames, complicated lever mechanisms, and other bulky mechanisms. Finally, friction in the system is minimized.

It is understood that the above is merely a preferred embodiment of my invention and that many changes and alterations can be made thereof without departing from the broader aspects and spirit of the invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows.

1. A floor-treating machine having a floor-treating element and means for regulating the relative elevation of said floortreating element comprising: a first frame and a second frame; said first and second frame pivotally mounted with respect to each other; said floor-treating element being mounted on said first frame at a point spaced from the pivot axis between said first and second frames; floor engaging means for supporting said machine mounted on said second frame; means for controlling the angular spacing between said first frame and said second frame at a point spaced from said pivot axis comprising at least one block mounted to one of said first frame and said second frame and a corresponding wedge mounted on the other of said first and second frames; means for rectilinearly sliding one of said block and wedge with respect to the other thereof for varying the angular spacing between said first frame and said second frame and thereby varying the relative elevation of said floor-treating element with respect to the surface being cleaned.

2. The floor-treating machine described in claim 1 wherein said second frame extends substantially the full width of said first frame and has a floor contacting support on each side thereof adjacent its free end, a pair of said blocks and a pair of said wedges mounted at said free end of said second frame, one of said blocks and one of said wedges being adjacent each side of said second frame; said sliding means comprising means for simultaneously sliding the slidable one of said pair of blocks and wedges to the same extent on both sides of said machine, thereby varying the distance between said floortreating element and said surface being cleaned uniformly across the width of said machine.

3. The floor-treating machine described in claim 2 wherein said floor-treating element is mounted near one end of said first frame and said pivotal mounting between said first frame and said secondary frame is spaced therefrom towards the opposite end of said first frame from said floor-treating element.

4. The floor-treating machine of claim 1 in which a second support means for said machine is secured to said first frame near one end thereof, said fioor treating element being mounted near the end of said first frame opposite from said support for said first frame; said second frame being pivotally mounted to said first frame at one end of said second frame; said support means forsaid second frame comprising casters affixed to the opposite end of said second frame from said pivotal mounting; the distance between said pivoted end of said second frame and said castered end of said second frame being sufficiently long that the orientation of said second frame with respect to the surface being cleaned remains generally constant regardless of the angular spacing between said frame means.

5. The floor-treating machine of claim 2 in which a second support means for said machine is secured to said first frame near one end thereof, said floor-treating element being mounted near the end of said first frame opposite from said support for said first frame; said second frame being pivotally mounted to said first frame at one end of said second frame; said support means for said second frame comprising casters affixed to the opposite end of said second frame from said pivotal mounting; the distance between said pivoted end of said second frame and said castered end of said second frame being sufiiciently long that the orientation of said second frame with respect to the surface being cleaned remains generally constant regardless of the angular spacing between said frame means.

6. A floor-treating machine having a floor-treating element and means for regulating the relative elevation of said floortreating element comprising: a first frame and a second frame; said first and second frame pivotally mounted with respect to each other; said floor-treating element being mounted on said first frame at a point spaced from the pivot axis between said first and second frames; floor engaging means for supporting said machine mounted on said second frame; means for camming disposed between said first frame and said second frame at a point spaced from said pivot axis for controlling the angular spacing between said first frame and said second frame; means for actuating said cam means for varying the angular spacing between said first frame and said second frame and thereby varying the relative elevation of said floor-treating element with respect to the surface being cleaned and support means rotatably mounted on said first frame; said pivotal mounting between said first and second frames being concentric with the axis of rotation of said rotatable support.

7. A floor-treating machine having a floor-treating element and means for regulating the relative elevation of said floortreating element comprising: a first frame and a second frame, said second frame extending substantially the full width of said first frame; said first and second frame pivotally mounted with respect to each other; said second frame including a floorcontacting support on each side thereof adjacent its free end; said floor-treating element being mounted on said first frame at a point spaced from the pivot axis between said first frame and said second frame; floor engaging means for supporting said machine mounted on said second frame; and means for camming disposed between said first frame and said second frame at a point spaced from said pivot axis for controlling the angular spacing between said first frame and said second frame, said camming means comprising a pair of cams at said free end of said second frame, one of said earns being adjacent each side of said second frame; means for actuating said cam means comprising means for simultaneously activating said pair of cams to the same extent on both sides of said machine for varying the angular spacing between said first frame and said second frame and thereby varying the relative elevation of said floor-treating element with respect to the surface being cleaned in a uniform manner across the width of said machine and support means rotatably mounted on said first frame; saidpivotal mounting between said first and second frames is concentric with the axis of rotation of said rotatable support.

8. The floor-treating machine described in claim 7 in which said cam means includes an inclined ramp and ramp engaging block, one of said ramp and said block being movable with respect to the other for varying the position of said block along said ramp.

9. The floor-treating machine described in claim 5 wherein the movable ones of said pair of wedges and said pair of blocks are mounted on a common threaded shaft and are simultaneously shifted an equivalent distance by rotation of said shaft; said machine including holding means adjacent each said movable one of said wedge and block such that said movable one of said wedge and block is held against rotation when said threaded shaft is rotated.

10. The floor-treating machine described in claim 8 wherein the movable one of said ramp and said block of both said cam means are mounted on a common threaded shaft and are simultaneously shifted an equivalent distance by rotation of said shaft; said machine including holding means adjacent the movable one of said ramp and block of both said cam means such that said movable one of said ramp and block is held against rotation when said threaded shaft is rotated.

11. The floor-treating machine of claim 4 in which said casters have pintles mounted in said second frame perpendicular to said floor; said pintles maintaining said perpendicular relationship to said supporting surface throughout the range of actuation of said earns.

12. The floor-treating machine of claim 5 in which said casters have pintles mounted in said second frame perpendicular to said floor; said pintles maintaining said perpendicular relationship to said supporting surface throughout the range of actuation of said earns.

13. A cleaner or the like having a floor-treating element and means for regulating the relative elevation of said floor-treating element comprising: a first frame; a rotatable support mounted on said first frame; a second frame having a pair of arms connected by a cross member; each of said arms being pivotally connected to said first frame concentrically with the axis of rotation of said support; a support member mounted on each of said arms at a point spaced from their pivotal mounting; said floor-treating element mounted on said first frame at a point spaced from said axis of rotation; said second frame having a ramp located on each of said arms at a point spaced from said axis of rotation; a threaded shaft mounted on said first frame and extending over both of said ramps; each of said ramps having a surface inclined with respect to said threaded shaft; two block members threaded on said shaft and held against rotation with respect thereto, each being adjacent one of said ramps and engaging said inclined surface thereof.

14. The device of claim 13 in which each of said ramps has an open ended slot at the upper end of said inclined surface such that said ramp will not engage said threaded shaft even with said block at the lower end of said inclined surface.

17. The device of claim 16 in which holding means for said blocks is provided, said holding means being a channel member fixedly mounted adjacent each of said block members; said channel member having a pair of opposite walls, one on each side of said block member and spaced closely adjacent thereto.

Claims

2. The floor-treating machine described in claim 1 wherein said second frame extends substantially the full width of said first frame and has a floor contacting support on each side thereof adjacent its free end, a pair of said blocks and a pair of said wedges mounted at said free end of said second frame, one of said blocks and one of said wedges being adjacent each side of said second frame; said sliding means comprising means for simultaneously sliding the slidable one of said pair of blocks and wedges to the same extent on both sides of said machine, thereby varying the distance between said floor-treating element and said surface being cleaned uniformly across the width of said machine.

4. The floor-treating machine of claim 1 in which a second support means for said machine is secured to said first frame near one end thereof, said floor-treating element being mounted near the end of said first frame opposite from said support for said first frame; said second frame being pivotally mounted to said first frame at one end of said second frame; said support means for said second frame comprising casters affixed to the opposite end of said second frame from said pivotal mounting; the distance between said pivoted end of said second frame and said castered end of said second frame being sufficiently long that the orientation of said second frame with respect to the surface being cleaned remains generally constant regardless of the angular spacing between said frame means.

5. The floor-treating machine of claim 2 in which a second support means for said machine is secured to said first frame near one end thereof, said floor-treating element being mounted near the end of said first frame opposite from said support for said first frame; said second frame being pivotally mounteD to said first frame at one end of said second frame; said support means for said second frame comprising casters affixed to the opposite end of said second frame from said pivotal mounting; the distance between said pivoted end of said second frame and said castered end of said second frame being sufficiently long that the orientation of said second frame with respect to the surface being cleaned remains generally constant regardless of the angular spacing between said frame means.

6. A floor-treating machine having a floor-treating element and means for regulating the relative elevation of said floor-treating element comprising: a first frame and a second frame; said first and second frame pivotally mounted with respect to each other; said floor-treating element being mounted on said first frame at a point spaced from the pivot axis between said first and second frames; floor engaging means for supporting said machine mounted on said second frame; means for camming disposed between said first frame and said second frame at a point spaced from said pivot axis for controlling the angular spacing between said first frame and said second frame; means for actuating said cam means for varying the angular spacing between said first frame and said second frame and thereby varying the relative elevation of said floor-treating element with respect to the surface being cleaned and support means rotatably mounted on said first frame; said pivotal mounting between said first and second frames being concentric with the axis of rotation of said rotatable support.

7. A floor-treating machine having a floor-treating element and means for regulating the relative elevation of said floor-treating element comprising: a first frame and a second frame, said second frame extending substantially the full width of said first frame; said first and second frame pivotally mounted with respect to each other; said second frame including a floor contacting support on each side thereof adjacent its free end; said floor-treating element being mounted on said first frame at a point spaced from the pivot axis between said first frame and said second frame; floor engaging means for supporting said machine mounted on said second frame; and means for camming disposed between said first frame and said second frame at a point spaced from said pivot axis for controlling the angular spacing between said first frame and said second frame, said camming means comprising a pair of cams at said free end of said second frame, one of said cams being adjacent each side of said second frame; means for actuating said cam means comprising means for simultaneously activating said pair of cams to the same extent on both sides of said machine for varying the angular spacing between said first frame and said second frame and thereby varying the relative elevation of said floor-treating element with respect to the surface being cleaned in a uniform manner across the width of said machine and support means rotatably mounted on said first frame; said pivotal mounting between said first and second frames is concentric with the axis of rotation of said rotatable support.

11. The floor-treating machine of claim 4 in which said casters have pintles mounted in said second frame perpendicular to said floor; said pintles maintaining said perpendicular relationship to said supporting surface throughout the range of actuation of said cams.

12. The floor-treating machine of claim 5 in which said casters have pintles mounted in said second frame perpendicular to said floor; said pintles maintaining said perpendicular relationship to said supporting surface throughout the range of actuation of said cams.

15. The device of claim 13 in which stop means is located on said threaded shaft, at least one such stop means being located on either side of one of said block members to restrict the length of travel of said block member.

16. The device of claim 14 in which stop means is located on said threaded shaft, at least one such stop means being located on either side of one of said block members to restrict the length of travel of said block member.