US2205671A

US2205671A - Weight balancing mechanism

Info

Publication number: US2205671A
Application number: US222431A
Authority: US
Inventors: Ira C Sarber
Original assignee: FINNELL SYSTEM Inc
Current assignee: FINNELL SYSTEM Inc
Priority date: 1938-08-01
Filing date: 1938-08-01
Publication date: 1940-06-25
Anticipated expiration: 1957-06-25

Description

June 1940- C. SARBER 2,205,671

WEIGHT BALANCING MECHANISM Filed Aug. 1, 1938 3 z f5 v i a Z;

WI -LL.

11v VENTOR [7'62 5ar 11 A z rolezws ys Patented June 25, 1940 WEIGHT BALANCING l Ira c. Sarber, Elkhart, Ind, assignoruto Finnell System, Inc., Elkhart, Ind; a corporation of Indiana Application August 1, 1938, Serial No. 222,431 1 I Claims.

This invention relates'to weight counterbalancing devices particularly suitable for floor scrubbing machines. i

The main objects of this invention are to provide an improved counterbalancing device adapted to maintain a substantially constant or uniform pressure on the bristles of a floor scrubber regardless of the amount of wear of the bristles; to provide a weight counterbalancing device which is of simple construction and free of mechanical troublesso as to give 'satisfactoryservice over a long period of time; and to provide a weight counterbalancing device which is readily adjustable to accommodate varying conditions and specified requirements. I

An allustrative embodiment of this invention is shown in the accompanying drawing, in which:

Fig. 1 is a fragmentary view, partly in elevation and partly in section, of a floor scrubbing machine equipped with the improved weight balancing unit.

Fig. 2 is an enlarged sectional view, taken on the line 2-2 of Fig. 1, looking in the direction indicated by the arrows.

Fig. 3 is a fragmentary view showing one arm of the bell crank and its axis of pivotalsupport with relation to the center from which the arcuate cam slot therein is formed.

In the construction of power driven floor scrub so bing machines, it has been found most satisfactory to build the electric driving motor and gear freely swingable in a vertical plane. In this ma nner, the floor scrubbing brushes are maintained in contact with the floor at all times regardless of the unevenness thereof.

However, in the manufacture of the larger sizes of floor scrubbing machines, an electric motor of considerable size and weight is required order to have suflicient power for rotating the relatively large scrub brush unit. The weight of such a heavy motor and gear box, restingupon the bristles. of the scrubbing brushes, has a tendency to bend them over and therefore the necessity has arisen for providing the motor and brush unit with suitable counterbalancing means which will tend to relieve the brush bristles of a portion of their load and at the same time permit" a required weight or pressure thereon so as to secure an effective and desirablescrubb ing action of the brush bristles.

In other words, scrubbing brushes'of this character do not operate to the best advantage if too much weight is placed thereon. On the other hand,-there must be enough weight on the bristles to cause them to perform and work in an efficient manner. Furthermora'provision must be made for automatically maintaining this desired amount of weight upon the brush bristles as the s PATENT OFFICE.

bri stleswear away and become shorter during long periods of use.

In the construction shown in the drawing, the 'front end of afloor scrubbing machine frame In is shown provided with a wheel or roller l I, which is adapted to rest upon and traverse/the floor being scrubbed, the wheel ll being journaledon a shaft 12. The shaft l2 also pivotally supports the rear'end of a forwardly extending arm l3, the front end ofwhich is rigidly attachedto an electric'moto'r 14, so as to be freely swingable in a ver tical plane. The motor I4 is provided with a gear reduction case [5 rigidly connected thereto, which, through suitable reduction gears, not shown, permits the motor M to rotate a vertically disposed shaft [6 which depends from theunder side of the gear box l5.

Thelower end of the driving shaft I6 is con-I ll andmountings for the brushes l8"are shown in the 'co-pending application of Walter S. Finn'ell, Serial No. 211,633, filed June 3, 1938, and

assigned to the assignee of the present invention. Means are provided for partially counterbalancing the weight of the motor l4 and its unitary reduction gear and case and comprise a bell crankj member'generally designated 20, which-is pivotally supported on a pin 2| so as to swing in a 'verticalplane parallel tothe plane'of movement of the motor and brush unit. The pin 2| is rigid- 1y mounted-at its opposite ends at the top end of an upstanding'bracket 22, the lower end 23 of which is'welded or otherwise rigidly secured to a forwardly extending arm 24 of the frame 10.

The bell crank 20 is provided with two arms, one 1 of which, 25, is provided with a transversely extending conical shaped aperture 26 through which extends one end of a rod 21. The end of the rod 21 extending therethrough is provided with a semi-spherical head 28 which rests against the topsurface of the arm 24 and permits limited swinging movement of the rod 21 within the conical shaped aperture 26. The other end of the rod 27 is threaded into one end of a turnbuckle 29, the other end of which threadably receives one end of a rod 30. The other end of the rod 30 is pivoted at 3| in an upstanding clip 32 which is rigidly secured to the top of the motor M. The two rods 21 and 30 with the connecting turnbuckle 29 provide an adjustable link connection between the bell crank arm 25 and the motor and brush unit.

The other arm 33 of the bell crank member 2|] is provided with an arcuate slot 34, the radius of which is taken from a center point offset with respect to the axis of pivotal movement of the bell crank, i. e., offset with respect to the axis of the bell crank pivot pin 2|, as shown most clearly in Fig. 3 of the drawing, thus forming a cam slot.

The slot 34 receives and the side walls thereof snugly embrace a roller 35 which is journaled on one side of and at the top end of a substantially vertically disposed rod 36. The rod 36 extends through an aperture in the top end of an inverted cup shaped cylindrical member 37 which houses a helical compression spring 38. One end of the compre sion spring 38 bears against the under side of the closed upper end of the cup 37, and the other end thereof bears against a washer all, which is adjustably positioned relative to the rod 36 for varying the tension on the spring, by a nut 56 which is threaded on the lower end of rod 35. The cup member 31 is welded or otherwise rigidly secured to the bracket 22 and positioned so that the axis of the rod 36 is offset or in spaced relation to the axis of pivotal support of the bell crank member 29.

In the operation of this device suitable tension is placed on the spring 38 by the nut 40, and the motor unit is connected to the arm 25 of the bell crank in proper relation to the length of the bristles of the brush if! by adjustment of the turnbuckle 29. In this position the roller 35 is near the left hand end of the cam slot 34. As the bristles wear off of the brushes during the normal use thereof, the motor unit and brush holding unit, lowers toward the floor, at which time the bell crank is rotated clockwise, as viewed in the drawing, whereupon the cam slot 34 raises the rod 3i; and further compresses the compression spring 38.

Although but one specific embodiment of this invention has been herein shown and described, it will be understood that numerous details of the construction shown may be altered or omitted without departing from the spirit of this invention as defined by the following claims.

What is claimed is:

1. In floor scrubbing machine, a frame, a scrubbing brush movably connected to said frame and tending to move downwardly by force of gravity, a weight balancing device for said brush mounted on said frame, including a bell crank pivotally supported by said frame, a link connecting one arm of said bell crank to said brush, the other arm of said bell crank having a cam slot therein, and yielding means acting between said frame and cam slot tending to rotate said bell crank in a direction to counterbalance the weight of said brush.

2. In a floor scrubbing machine, a frame, a scrubbing brush movably connected to said frame and tending to move downwardly by force of gravity, a weight balancing device for said brush mounted on said frame, including a bell crank pivotally supported by said frame, an adjustable link connecting one arm of said bell crank to said brush, the other arm of said bell crank having a cam slot therein, and yielding means acting between said frame and cam slot tending to 1'0- tate said bell crank in a direction to counterbalance the weight of said brush.

3. In a floor scrubbing machine, a frame, a scrub brush pivotally connected to said frame so as to tend to swing downwardly by force of gravity, a device mounted on said frame for counterbalancing the weight of said brush, said device including a bell crank pivoted on said frame, a link connecting one arm of said bell crank to said brush, the other arm of said bell crank having an arcuate slot therein, the center from which said slot is formed being offset with respect tothe axis of pivotal support of said bell crank, anti yielding means acting between said frame and cam slot tending to rotate said bell crank in a direction to counterbalance the weight of said brush.

4. In a floor scrubbing machine, a frame, a scrub brush pivotally connected to said frame so as to tend to swing downwardly by force of gravity, a device mounted on said frame for counterbalancing the weight of said brush, said device including a bell crank pivoted on said frame, a link connecting one arm of said bell crank to said brush, the other arm of said bell cranl: having an arcuate slot therein, the center from which said slot is formed being offset with respect to the axis of pivotal support of said bell crank, a rod slldably mounted on said frame and having axial movement relative thereto, a roller pivoted on said rod and embraced by the side walls of said cam slot, and a helical compression spring bearing between said frame and said rod for causing said roller .to bear against a wall of said cam slot and thereby tend to rotate said bell crank in a direction to counterbalance the weight of said brush.

5. In a floor scrubbing machine, a frame, a scrub brush pivotally connected to said. frame so as to tend to swing. downwardly by force of gravity, a device mounted on said frame for counterbalancing the weight of said brush, said device including a bell crank pivoted on said frame, a link connecting one arm of said bell crank to said brush, the other arm of said hell crank having an arcuate slot therein, the center. from which said slot is formed being offset with respect to the axis of pivotal support of said bell crank, a rod slidably mounted on said frame and having axial movement relative thereto, the axis of said rod being offset with respect to the center of pivotal connection of said bell crank and with respect to the center about which said cam slot is formed, a roller pivoted on said rod and embraced by the side walls of said cam slot, and a helical compression spring bearing between said frame and said rod for causing said roller to bear against a wall of said cam slotand thereby tend to rotate said bell crank in a direction to counterbalance the weight of said brush.

IRA C. SARBER.