US 3909987 A
A device for adjusting idler pulleys to insure proper alignment of two or more pulleys to prevent belt slippage. The device has a first adjustable member attached to a frame with a second adjustable member attached to the first. The first and second members are adjustable about mutually perpendicular axes. The idler pulley is supported on a shaft attached to the second member for rotation about a third axis, substantially perpendicular to the first two axes. An adjusting arm having a pair of substantially perpendicular slots controls rotation of the first member within limits.
Description (OCR text may contain errors)
United States Patent [191 MacCarthy, Sr.
[ Oct. 7, 1975 IDLER PULLEY ADJUSTMENT DEVICE  Inventor: Donald W. MacCarthy, Sr., 11227 E. Rincon Dr., Whittier, Calif. 90606  Filed: Dec. 18, 1974  Appl. No.: 534,036
 U.S. Cl. 51/148; 74/242.15 R  Int. Cl? B24B 21/00; B24B 23/06; B24B 25/00  Field of Search 51/135-148; 74/2428, 242.15 R
 References Cited UNITED STATES PATENTS 2,449,519 9/1948 Sutton 51/148 2,706,367 4/1955 MacCarthy.... 51/148 3,127,712 4/1964 Krogen et a1. 51/148 Primary Examiner-Othell M. Simpson Attorney, Agent, or Firm-Jessup & Beecher  ABSTRACT A device for adjusting idler pulleys to insure proper alignment of two or more pulleys to prevent belt slippage The device has a first adjustable member attached to a frame with a second adjustable member attached to the first. The first and second members are adjustable about mutually perpendicular axes. The idler pulley is supported on a shaft attached to the second member for rotation about a third axis, substantially perpendicular to the first two axes. An adjusting arm having a pair of substantially perpendicular slots controls rotation of the first member within limits.
5 Claims, 3 Drawing Figures waws? US. Patent 0a. 7,1975
IDLER PULLEY ADJUSTMENT DEVICE BACKGROUND OF THE INVENTION This invention relates to devices for adjusting idler pulleys and more particularly to devices for adjusting such pulleys used in a belt sanding machine.
This device is an improvement of the adjustment means disclosed in US. Pat. No. 2,706,367 and is par ticularly useful in machines having a sanding belt tightly wound on three co-planar pulleys. A frequent problem with sanders of these types is the slippage and loosening of the sanding belt due to misalignment of the pulleys. At times, if not corrected, the belt may even come off which could result in damage to a workpiece or even injury. For this reason it is important that the belt be accurately centered on properly aligned pulleys during operation of the sander.
It was found that accurate centering of the belt was sensitive to alignment of the pulleys. This knowledge resulted in the development of the invention described in the above-mentioned patent. The adjustment device disclosed in that patent has provided a satisfactory solution to the adjustment problem. However, it was re cently realized that improvements in the adjusting mechanism could be made.
Part of the mechanism included a finger having an off-center boss engaging an arm. The adjustment is not as simple as it could be because the adjusting finger can make a complete revolution of 360. Also the snug fit of the boss and arm can easily bind by being clogged with the dust from the sander.
Since only slight adjustments of the idler pulley are necessary, it was found that a flat adjustable arm using loose-fitting slots not only provided a much freer adjustment but also provided a convenient guide to limit the maximum adjustment. Also the device is easier to assemble and disassemble and has one less part.
It is one object of the present invention to provide an idler pulley adjustment device which has an adjusting arm with a slot for guiding and limiting maximum adjustment.
Another object of the present invention is to provide an idler pulley adjustment mechanism having an adjustment arm with mutually perpendicular slots which simplify assembly and disassembly and eliminate binding.
These and other objects will become apparent when the description is considered in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an end elevation of a belt sander in partial section illustrating the use of the adjustment device.
FIG. 2 is a perspective fragmentary view of the adjustment device as attached to a belt sander.
FIG. 3 is an exploded perspective view of the adjustment device as shown in FIG. 2.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a belt sanding machine is shown having an upright frame and a base 12 for attachment to a workbench. The sander has a drive pulley 14 and may have two idler pulleys, one of which is shown at 16. The pulleys l4 and 16 are substantially co-planar and are rotatably mounted on spaced horizontal axes. A sanding belt 18 is tightly wound on the pulleys l4 and 16. The drive pulley 14 is connected by a shaft 20 to a V-be lt pulley 22 which is coupled to any suitable drive means such as an electric motor.
In order to center and maintain belt 18 on the pulleys during operation of the sander, adjustment of one of the pulleys'to insure proper alignment is necessary. Accordingly means for adjusting idler pulley 16 is provided. The adjusting device provides adjustment of shaft 24 supporting pulley 16 about two axes.
The adjustment device is supported by a hanger 26 bolted to the frame 10. The hanger 26 has a hole through which the shaft 28 of a first adjustable member 30 passes. The shaft 28 terminates in a squared portion 32 which extends above the hanger 26. A second adjustable member in the form of a pulley support 34 is rotatably attached to the first adjustable member 30 by a pintle pin 36 passing through the two members. Shaft 24 is rigidly attached to pulley support 34 and idler pulley 16 is rotatably mounted by suitable roller or ball bearings not shown.
The first adjustable member 30 is secured in the hanger 26 by a nut 38. In between the nut 38 and hanger 26 is an elongated flat adjusting arm 40 which has a finger tab 42. The arm 40 is provided with a first lengthwise slot 44 which closely fits the squared portion 32 of adjustable member 30. A second slot 46 substantially perpendicular to slot 44 is provided to guide and limit adjustment of arm 40. A threaded shaft 48 passing through slot 46 into threaded hole 50 in frame 10 guides and limits the adjustment of the arm 40. After adjustment of the pulley 16, the arm 40 is secured against arcuate movement by tightening down locking knob 52 integrally attached to threaded shaft 48. Since both slots 44 and 46 are not tight fits, assembly and adjustment is simplified.
The adjustment of arm 40 is translated to a rotation adjustment of idler pulley 16 through the squared portion 32 of first adjustable member 30. Adjustment about the other axis is accomplished through handwheel 54 and threaded shaft 56 whose end butts up against pulley support 34 below pintle pin 36. The tension in belt 18 keeps the pulley support 34 constantly pressed against the end of shaft 56. Rotation of handwheel 54 moves shaft 56 in or out, causing pulley support 34 to rotate about pintle pin 36. To produce rotation of shaft 24 about a vertical axis, knob 52 has to be loosened and arm 40 arcuately adjusted by means of finger tab 42. When the adjustment is set, knob 52 is tightened down securing arm 40 against any movement.
Obviously many modifications and variations will become apparent to those skilled in the art. Therefore, within the scope of the appended claims the invention may be practiced other than as specifically cited.
What is claimed is:
1. A device for adjusting an idler pulley comprising:
an upright frame;
a first adjustable member rotatably attached to said frame for adjustment about a first axis, said first adjustable member having a square shoulder portion terminating in a round threaded shaft;
a second adjustable member rotatably attached to said first member for adjustment about a second axis substantially perpendicular to the first axis;
an idler pulley rotatably supported by said second member on a third axis substantially perpendicular to said first two axes;
an elongated flat adjusting arm having a first lengthwise slot in one end engaging the square shoulder portion of the first adjustable member, said arm having a second slot substantially perpendicular to the first; and
guide means passing through said second slot for limiting arcuate adjustment of said first member.
2. The device according to claim 1 wherein said guide means includes:
means for securing said adjusting arm against arcuate movement after adjustment.
3. A belt sanding machine comprising:
a drive pulley rotatably attached to said frame;
a first adjustable member rotatably attached to said frame, said first adjustable member having a square shoulder portion terminating in a round threaded shaft;
a second adjustable member rotatably attached to said first member for adjustment about a second axis substantially perpendicular to the first axis; an idler pulley substantially co-planar with said drive pulley and rotatably supported by said. second member on a third axis substantially perpendicular to said first two axes; a sanding belt around said pulleys; an elongated, flat adjusting arm having a first lengthwise slot in one end engaging the square shoulder of said first member, said arm having a second slot substantially perpendicular to the first; and guide means passing through said second slot for limiting arcuate adjustment of said arm. 4. The belt sanding machine according to claim 3 wherein said guide means includes:
means for securing said adjusting arm against arcuate movement after adjustment. 5. The belt sander according to claim 3 further including a second idler pulley rotatably attached to said frame.