WO2003104682A1 - Self-tensioning motor mount for drive assembly - Google Patents

Abstract

A self-tensioning motor mount (22) having an anchorable base (24), a motor receiving platform (26) operatively engaged therewith so as to be pivotable about a pivot axis (28), and a pivot regulating mechanism (56) is provided. The pivot regulating mechanism (56) preferentially permits pivoting of the motor receiving platform (26), relative to the anchorable base (24), in a belt tightening direction, as opposed to a belt slackening direction. By such structure, an increase in belt tension during acceleration of a driven device (34), and a commensurate decrease in belt tension during sustained operation of the driven device (34) is permitted.

Description

SELF-TENSIONING MOTOR MOUNT FOR DRIVE ASSEMBLY

This is a regular application filed under 35 U.S.C. §111 (a) claiming priority under 35 U.S.C. §119 (e) (1), of provisional application Serial Nos. 60/387,348, 60/387,349, and 60/387,456, each having a filing date of June 10, 2002 and filed under 35 U.S.C. §111 (b) .

TECHNICAL FIELD

The present invention relates to an apparatus for use with motor assemblies, more particularly to a self-tensioning motor mount wherein a pivot regulating mechanism is provided to counteract pivot motion in a belt slackening direction in furtherance of minimizing drive assembly instability.

BACKGROUND OF THE INVENTION

It is commonly known to utilize a motor to drive a device by attaching a continuous belt between the motor and the device to be driven. One problem encountered with regard to motor assemblies that utilize drive belts is that when the motor begins to turn the belt, there is an increase in the tension of the belt, and once the motor is up to operating speed, the belt tension decreases. This problem increases and decreases the stretch of the belt, and over time reduces the life of the belt, occasionally breaking the belt when the tension becomes too great or when the belt becomes weakened from excessive stretching. Additionally, there are a wide range of other detrimental problems that may result from a design that permits significant changes in belt tension, or permits a loose fitting belt, such as, for example, noise, vibration and potentially harmonic resonance, uncoupling of the belt from the motor and/or driven device, and reduction in motor bearing life. Since maintaining proper belt tension allows for higher motor efficiency and longer belt life, anything that permits the belt to greatly slacken and/or stretch should be avoided.

One solution to these problems has been to provide an assembly wherein the motor pivots so that, as the belt drive slackens, the motor pivots away from the driven device, thereby tightening the belt. However, with a freely pivotable design, the motor is not prevented from pivoting toward the driven device, nor is the movement of the motor limited or otherwise regulated (e.g., restrained, damped, etc.) in any way. This typically results in the motor bouncing due to the alternating slacking and tightening of the belt drive acting between the drive and driven sheaves . In this way, the problem has changed from merely having a moving belt, to involving a moving belt and motor. With this arrangement, the problems of noise, vibration, and potentially harmonic resonance may also be evident in the motor itself. The most common causes for assembly instability is resonance with the belt rotational speed or natural frequency of the belts, the belt acting as a spring and the motor as a mass in a simple mass-spring system. With the motor adding mass to the moving system, stretching of the belt is exacerbate.

Heretofore known corrective measures for drive assembly instability, wherein a pivot base is used, have included the addition of restraining means to the pivot base so as to counteract or selectively counterbalance the tensioning effect of the pivot base (i.e., prevent or limit the motor from pivoting back toward the driven device) . For instance, U.S. Pat. No. 5,921,876 discloses a pivotal motor mount for tensioning a belt drive with a one-way restraint, thus permitting pivotal movement in only a tensioning direct. A series of clutch elements, positioned on the mount proximal to a driven device, oppose the forces that induce deleterious hop. As effective as such device may be at maintaining or maximizing drive tension, such design is not responsive to operational parameters effecting drive assembly dynamics and/or mechanics, for instance start-up versus full speed system torque, and its drive assembly implications. Thus, there remains a need to provide an improved pivot regulating mechanism, preferably a "smart" self-tensioning motor mount for a drive assembly which is responsive to system dynamics in furtherance of stable, low maintenance drive assembly operation. SUMMARY OF THE INVENTION

The present invention provides embodiments of a motor base for use with motors utilized with a continuous drive belt wherein one or more mechanisms are employed to slow/reduce the amount of movement of the motor and belt to thereby limit the tightening and slacking permitted by the belt, thus greatly reducing deleterious instability in the self-tensioning drive assembly due to belt skipping, hopping, etc. Embodiments of the present invention provide dampening, cushioning or other regulating mechanisms that control the movement of the motor in a belt tensioning direction and/or in an opposite belt slackening direction. A portion of the motor base of the present invention may be integrally part of a motor housing, or may be a separate unit. The motor base generally includes a pivotable motor receiving member, an anchorable base, and a pivot regulating mechanism.

The pivoting member, on which the motor is mounted or integrated therewith, is pivotally mounted to an anchorable base allowing the pivoting member to pivot relative to same. The movement or motion of the motor and pivoting member can generally be described as being in either a belt tensioning direction or in an opposite, belt slackening direction.

The pivot regulating mechanism is generally, but not necessarily, connected between the base and pivoting member for providing a counterbalancing or opposing force in at least one direction of pivotal movement of the motor. In this way, the regulating member provides a force against which the motor movement must overcome before the motor begins to move, and continues to provide a generally opposite force during the movement of the motor. Accordingly, the movement of the motor is slowed and the distance that the motor travels may be reduced. Further, in some embodiments, the regulating member may act to absorb some of the energy utilized to move the motor and pivoting member by converting mechanical energy into thermal energy. It is preferred that the pivoting member retain the ability to move from a first position to a second position, and substantially return to its initial first position while the regulating member is providing force during the movement of the pivoting member.

There are several advantages that use of a regulating mechanism can provide. For example, the amount of movement of the belt and motor is reduced and, therefore, stress on the material of the belt is reduced which lowers the risk of breakage of the belt and lowers the rate and extent of stretching of the belt. Additionally, by slowing the movement of the motor, the frequency at which the motor moves from its maximum distance from the driven device to its minimum distance is reduced and thereby the tendency for bouncing or harmonic oscillation of the motor is reduced. These and other features and advantages of the present invention will be apparent to those skilled in the art particularly through the drawings and their detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 generally illustrates a self-tensioning drive assembly, more particularly, a motor mounted upon a motor support structure having a pivotable platform;

FIGS. 2 illustrates physical relationships between select elements of the assembly components of FIG. 1;

FIG. 3 is an orthogonal overhead view of a motor support structure of the subject invention;

FIG. 4 is a top view of the motor support structure of FIG. 2;

FIG. 5 is an end view of the motor support structure of FIG. 3, taken along line 5-5 thereof;

FIG. 6 is an orthogonal overhead view of an alternate motor support structure of the subject invention;

FIG. 7 is a top view of the motor support structure of FIG. 5;

FIG. 8 is an end view of the motor support structure of FIG. 6, taken along line 8-8 thereof;

FIG. 9 is an orthogonal overhead view of further, alternate motor support structure of the subject invention;

FIG. 10 is a top view of the motor support structure of FIG. 8;

FIG. 11 is an end view of the motor support structure of FIG. 9, taken along line 11-11 thereof; FIG. 12 is an orthogonal overhead view of still a further, alternate motor support structure of the subject invention; and,

FIGS. 13A-D illustrate a stepwise functionality of the motor support structure of FIG. 13.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides embodiments of a self- tensioning motor support structure or mount for use with motors utilizing a continuous drive belt wherein a variety of pivot regulating mechanisms are employed to regulate (e.g., slow, reduce and/or counterbalance) the amount of movement of the belt and motor, in a belt slackening direction, thereby minimizing instability in a drive assembly incorporating same. Regulation or control of the self-tensioning mechanism is desirable and advantageous, having a direct and significant impact upon stable drive assembly operation, and thus reduced operational costs for such assemblies.

With general reference to FIGS. 1-3 (see also the embodiments of FIGS. 6, 9, & 12 having reference numerals +100, +200, and +300, for like structures respectively) , there is shown a characteristic self-tensioning drive assembly 16. The self-tensioning drive assembly 16 generally includes a driving device 18, such as a motor, having an output shaft 20, supported upon or by a driving device support structure 22 which preferably includes an anchorable base 24 and a motor receiving platform 26 operatively engaged therewith so as to be pivotable about a pivot axis 28. A drive 30 operatively joins the output shaft 20 of the driving device 18 with an input shaft 32 of the driven device 34, the drive 30 generally including a drive sheave 36, a driven sheave 38, and an endless loop 40 such as a belt. Directional movement of the motor 18, mounted in a manner so as to provide a self-tensioning drive assembly, may be generally characterized as being in either a belt tensioning direction (T) , a direction distal to the driven device, or, in an belt slackening direction (S) , a direction proximal to the driven device.

As previously noted, the driving device support structure 22 (i.e., self-tensioning motor mount) of the subject assembly 16 generally includes an anchorable base 24 and a selectively positionable platform 26, pivotable, with respect to the base 24, about a pivot axis 28. Preferably, but not necessarily, the driving device 18 is selectively affixed to the platform 26, the platform 26 being operatively engaged or engagable as previously outlined, or, more generally, as is well known to those of ordinary skill with same. It is to be understood that the platform may alternately be integrally formed with a housing of the driving device, or more generally, the functionality of the platform (i.e., pivoting or tilted support) may be incorporated into the driving device so as to eliminate such structure from the driving device structure as described .

The motor receiving platform 26 of the self-tensioning motor mount 22 generally, but not necessarily, includes a pair of spaced apart arms 42, each of the arms 42 being adapted so as to selectively receive or variably position the motor 18 therealong, as will be later discussed. An upper surface 44 of each of the platform arms 42 includes at least a single slot 46 into which is receivable a portion of the motor 18, or mounting hardware therefore, for securing same to the platform 26. A shaft 48 or equivalent structural linkage, through which the pivot axis 28 substantially passes, connects the arms 42 of the platform 26, and unites same with the anchorable base 24.

The anchorable base 24 of the self-tensioning motor mount 22 generally, but not necessarily, includes a pair of spaced apart brackets 50, each of the brackets 50 being adapted so as to selectively receive or variably position the motor receiving platform 26 therealong, as will be later discussed. The brackets 50, as shown, generally include platform engaging portions 52 and anchor receiving portions 54. Each of the platform engaging portions 52 of the brackets includes at least a single slot or guide into which a shaft receiving structure is received or insertable .

With particular reference now to FIG. 2, several physical relationships between the driving device 18 and the preferred driving device support structure 22, and/or inherent with each, are noted. Typically, and preferably, the driving device 18 is variably positionable with respect to the platform 26 of the self-tensioning motor mount 22, the platform 26 in turn being variable positionable with respect to the base 24 thereof. More particularly, the platform 26 of the driving support structure 22 is translatable with respect to the base 24 thereof so as to define a variable offset distance (Hpb) between the pivot axis 28 of the support structure 22 and the base 24 thereof (i.e., the pivot point of the platform relative to the base is variable) , and the driving device 18 is translatable with respect to the platform 26 upon which it is receivable so as to define a variable offset distance (Vpb) between the pivot axis 28 of the support structure 22 and the output shaft 20 of the driving device 18. Several inherent or fixed physical or spatial relationships are noted for the elements illustrated, more particularly, the height or thickness of the driving device support structure 22 (Rpb) (i.e., the distance between opposed parallel aligned exterior surfaces of the base and platform, or said another way, the distance between the "bottom" of base 24 and the "top" 44 of platform 26 when oriented so as to be parallel) ; the height of, or distance between, the pivot axis 28 relative to the bottom of the base 24 (Tpb) ; and, the height or distance between the driving device output shaft 20 centerline and the top 44 of the platform 26 (Dnema) . Critical to the self-tensioning motor mount of the subject invention, in all its embodiments, is a pivot regulating mechanism, preferably operatively disposed between portions of the anchorable base and the motor receiving platform. The pivot regulating mechanism is typically, but not necessarily, positioned so as to connect the motor receiving platform with the anchorable base. It is preferred that the pivot regulating mechanism provides an initial force which the motor movement must overcome.

The pivot regulating mechanism preferentially permits pivoting of the motor receiving platform, relative to the anchorable base, in belt tightening direction T, as opposed to belt slackening direction S, so as to thereby provide an increase in belt tension during acceleration of a driven device, and a commensurate decrease in belt tension during sustained operation of the driven device. The aforementioned general functionality of the pivot regulating mechanism is preferably achieved via utilization of dampening, biasing, and/or frictional elements. A detailed discussion of the pivot regulating mechanism follows with respect to the several embodiments of the self-tensioning motor mount of FIGS. 3, 6, 9, & 12.

Referring now generally to the embodiment of FIGS. 3-5, there is shown a pivot regulating mechanism 56 comprising at least a single shock absorber 58 (e.g., a piston-type mechanical, one-way, non-adjustable shock absorber, similar in design to those utilized in the automobile industry) disposed between portions of anchorable base 24 and the motor receiving platform 26. Generally, shock absorbers act to counteract the amount of force applied between two elements (i.e., structures), attached to the opposing ends of same, by converting some of the mechanical energy, used to provide the force, to thermal energy in the form of heat. Therefore, the amount of energy that is translated into movement of the elements is reduced.

Typically, and as illustrated, mechanical shock absorbers utilize a piston 60 mounted in a cylinder 62 filled with fluid. The cylinder 62 of the absorber 58 is shown mounted to a brace 64 of the anchorable base 24, with a free end of the piston 60 of the absorber 58 shown mounted indirectly to an arm 42 of the motor receiving platform 26. The attachment of the regulator components to the other motor mount components may be by any means known in the art. For example, as illustrated, one end of the regulating mechanism 56 is mounted to a portion of the platform 26, in this case brace 64, with a shoulder bolt 66. The shoulder bolt 66 may be attached to a cooperating nut or the brace 64 may be threaded to fix the shoulder bolt 66 in place.

The other end of the regulating mechanism 56, for example piton 60, is mounted to a bar 68, connected to arm 42 of platform 26, by shoulder bolt 66. In the embodiment shown, the motor support structure 22 has a pivot axle 48 with a bearing casing 70 attached thereon and the bar 68 mounted thereto.

It is preferred that the regulating mechanism be aligned with the direction of motor movement. For example, this may be accomplished by mounting the bar 68 perpendicular to the surface 44 of the pivoting arm 42 upon which the motor 18 is to be mounted, and by attaching the regulating mechanism to have connections to the bar 68 and support member 22, thereby allowing the regulating member to radially pivot with respect to both the support member 22 and the bar 68.

Additionally, shock absorbers, such as that shown in the figures, typically have a minimum and maximum extension length. As used in the present invention, these fixed dimensions can provide limits for the travel of the pivot member and, accordingly, can also limit the travel of the motor and the tension of the belt, and are therefore preferred. During the travel of the pivot member between the minimum and maximum limits of the regulating member, the regulating member converts some of the energy, used to move the pivot member, into heat and effectively slows movement of same.

The pivot regulating mechanism desirably may combine one or more similar or different dampening or biasing elements. Suitable shock absorbing elements may include, but not be limited to, mechanical and non-mechanical, adjustable and non-adjustable, and one-way or two-way devices. Furthermore, and as will be subsequently discussed, some elastomeric materials and more conventional spring designs may suitably provide a regulating or cushioning force adequate to counter balance heretofore known self- tensioning motor mounts .

The shock absorber slows the motion in its compression stroke, and allows free motion in the extension stroke. The extension stroke corresponds to the downward motion of the pivot base. At fan start-up, the additional torque required to accelerate the fan causes the motor to pivot freely downwardly, which maintains adequate belt tension to prevent belt slippage. As the fan reaches full speed, the shock absorber slows the return upward motion. Slowing the upward motion prevents motor hop. The subject design preserves one of the important benefits of the pivoting motor base, more particularly, the pivoting feature provides the additional belt tension required during fan acceleration, and then reduces the tension to adequate levels during normal operation. The benefit is an increase in belt life and reduce loads on the motors and fan bearings. Other anti-hop devices allow the base to pivot during start-up, but do not allow for any return motion, resulting in higher than necessary belt tension.

Referring now generally to the embodiment of FIGS. 6-8, there is shown a pivot regulating mechanism comprising a biasing web assembly 172 extending from a portion of the anchorable base 124. The web assembly 172 preferably includes a web or strap 174, and a energy dampening or tensioning assembly 176. A first end of the web 174 is fixed to a portion of the anchorable base 124, more particularly a brace 164 uniting the spaced apart brackets 150, so as to extend and wrap about the shaft 148 of the motor receiving platform 126. A free end of the web 174 is indirectly linked to the portion of the anchorable base 124 from which it generally extends via the tensioning assembly 176, which preferably includes a dampening element 178 (e.g., a spring as shown) and mechanism 180 for selectively adjusting the tension in the dampening element (e.g., a knob 182 threadingly received on a shaft 184 as shown). The tensioning assembly 176 permits a range of frictional engagement to be imparted to the shaft 148 of the motor receiving platform 126, via the web or strap 174, thereby slowing or preventing rotation the shaft, and thereby the motor receiving platform.

With motion in a belt slackening direction S, the fixed end of the webbing gets tighter and tighter as the shaft rotates, causing the webbing to tighten onto the shaft, increasing friction and slowing the motion. With motion in a belt tightening direction T, the spring expands as the webbing tries to get tighter, preventing the webbing from getting as tight and allowing easier, preferential motion in the that direction. In cases where belt resonance would cause belt hop, the webbing acts as a friction damper, reducing the amplitude of the vibration levels.

With regard to maintenance of a drive assembly utilizing the self-tensioning motor mount of FIGS. 6-8, belt installation/removal is quickly and easily achieved without the use of tools. To remove the drive components, the hand knob 182 of the tensioning assembly 176 is loosened, removing tension in the webbing 174 and thereby friction between the webbing 174 and the shaft 148. The motor receiving platform 126 is then rotated up until the belt(s) of the drive are loose enough to be removed. The hand knob 182 is then tightened to hold the motor receiving platform 126 in place. After removing the old belt(s) and installing new belt(s), the hand knob 182 is loosened until the motor receiving platform 126 just falls back into place. With the tensioning assembly 176 adjusted this way, motion will be free in the downward or belt tensioning direction, but restricted in the upward or belt slackening direction.

Referring now generally to the embodiment of FIGS. 9-11, there is shown a pivot regulating mechanism comprising at least a single wedge arm 286 interposed between the anchorable base 224 and the motor receiving platform 226 so as to limit pivot motion of the platform 226 in the belt slackening direction. As shown, a pair of wedge arms 286 are mounted or generally supported by a portion of the anchorable base 224, as by a shaft 286 traversing the spaced apart brackets 250 of same, so as to be pivotable about a pivot axis 290. The pivot axis 290 of the wedge arms 286 are substantially parallel with the pivot axis 228 of the motor receiving platform 226.

A free end of the wedge arm 286 is adapted so as to have at least a portion thereof received in an aperture or slot 292 in the arm 242 of the motor receiving platform 226. A spring or other biasing element 294 tethers the free end of the wedge arm 286 to the anchorable base 224. The wedge arms 286 are arranged at a steep angle with respect to the slot 292 of the platform 242, thereby allowing the pivot base 226 to rotate freely in the downward, belt tensioning direction. In the upward belt slackening direction, the arms 286 wedge against the margin of the slot 292 so as to prevent motion in said direction. The motor receiving platform of the self- tensioning motor mount thusly pivots downward during fan start-up, but the wedging action of the arms prevent any return upward motion. As a result, there is no reduction in belt tension as the motor comes up to full speed. Since free motion is allowed only in direction, hop due to belt resonance is eliminated. As in the previous embodiments, belt replacement requires no tools. To free up the pivot base so that upward motion is possible, the wedge arms are rotated away from the slot.

Referring now generally to the embodiment of FIGS. 12 & 13, there is shown a pivot regulating mechanism comprising at least a single cam arm 361 depending from the motor receiving platform 326, more particularly, the arms 342 thereof. The cam arms 361 are pivotably mounted near free ends of the arms 342 of the platform 326, more particularly, near free arm ends proximal to the driven device (i.e., the cam arms 361 are positioned on the platform 326 opposite the motor 318, or said another way, the cam arms 361 are positioned on one side of the pivot axis 328 of the platform 326, the motor 318 on the other side thereof) .

The cam arms 361 are weighted, or otherwise balanced so as to rotate (e.g., in a counterclockwise direction, see FIGS. 13A-13D) as the motor receiving platform 326 pivots in a belt tightening direction such that a camming surface 363 of the cam arm 361 maintains contact with the self-tensioning motor mount surface 365 (i.e., the surface or structure to/with which the anchorable base 324 is anchored) . The camming surface 363 of the arm 361 is shaped or otherwise configured so that as the motor receiving platform 326 pivots downward, a line from the cam arm pivot axis 367 to a contact point of the camming surface 363 with the base mounting surface 365 is most nearly perpendicular to same. Maintaining the point of contact as close as possible to perpendicular with the pivot axis 367; the cam arm maximizes the normal force, and thus the resulting friction, which works to resist any slipping of the camming surface 363 on the mounting surface 365.

Since various modifications can be made in my invention as herein above described, and many apparently widely different embodiments of same made within the spirit and scope of the claims without departing from such spirit and scope, it is intended that all matter contained in the accompanying specification shall be interpreted as illustrative only, and not in a limiting sense.

Claims

What is claimed is:

1. A self-tensioning motor mount comprising an anchorable base, a motor receiving platform operatively engaged therewith so as to be pivotable about a pivot axis, and a pivot regulating mechanism for preferentially permitting pivoting of said motor receiving platform, relative to said anchorable base, in a belt tightening direction, as opposed to a belt slackening direction, so as to thereby provide an increase in belt tension during acceleration of a driven device, and a commensurate decrease in belt tension during sustained operation of the driven device.

2. The self-tensioning motor mount of claim 1 wherein said motor receiving platform includes a pair of spaced apart arms.

3. The self-tensioning motor mount of claim 2 wherein said anchorable base includes a pair of spaced apart brackets.

4. The self-tensioning motor mount of claim 3 wherein each of said spaced apart arms are adapted so as to selectively receive a motor therealong.

5. The self-tensioning motor mount of claim 3 wherein each of said spaced apart arms are adapted so as to variably position a motor therealong .

6. The self-tensioning motor mount of claim 5 wherein each of said spaced apart brackets are adapted so as to selectively receive said spaced apart arms therealong.

7. The self-tensioning motor mount of claim 5 wherein each of said spaced apart brackets are adapted so as to variably position said spaced apart arms therealong.

8. The self-tensioning motor mount of claim 7 wherein said pivot regulating mechanism extends from a portion of said anchorable base .

9. The self-tensioning motor mount of claim 8 wherein said pivot regulating mechanism comprises an energy dampening element.

10. The self-tensioning motor mount of claim 8 wherein said pivot regulating mechanism comprises a biasing element.

11. The self-tensioning motor mount of claim 8 wherein said pivot regulating mechanism comprises a friction imparting element.

12. The self-tensioning motor mount of claim 8 wherein said pivot regulating mechanism comprises at least a single shock absorber.

13. The self-tensioning motor mount of claim 12 wherein said shock absorber links a portion of said motor receiving platform with said anchorable base.

14. The self-tensioning motor mount of claim 13 wherein said shock absorber resists pivot motion in a compression stroke, and permits pivot motion in an extension stroke.

15. The self-tensioning motor mount of claim 8 wherein said pivot regulating mechanism comprises a biasing web assembly extending from a portion of said anchorable base.

16. The self-tensioning motor mount of claim 15 wherein said motor receiving platform further includes a shaft.

17. The self-tensioning motor mount of claim 16 wherein said shaft links said spaced apart arms of said motor receiving platform.

18. The self-tensioning motor mount of claim 17 wherein said spaced apart arms are fixed to said shaft.

19. The self-tensioning motor mount of claim 18 wherein said biasing web assembly includes a elongate web fixed at an end thereof to a portion of said anchorable base so as to extend therefrom.

20. The self-tensioning motor mount of claim 19 wherein said elongate web extends so as to wrap about said shaft for frictional engagement therewith.

21. The self-tensioning motor mount of claim 20 wherein said elongate web is resiliently united, distal said fixed end thereof, with a portion of said anchorable base.

22. The self-tensioning motor mount of claim 20 wherein the resilient union is adjustable so as to selectively change resiliency.

23. The self-tensioning motor mount of claim 8 wherein said pivot regulating mechanism comprises at least a single wedge arm depending from said arm of said motor receiving platform.

24. The self-tensioning motor mount of claim 23 wherein said at least a single wedge arm is pivotable with respect to said arm of said motor receiving platform.

25. The self-tensioning motor mount of claim 24 wherein said at least a single wedge arm has a camming surface for engagement with a surface to which said anchorable base is affixed.

26. A motor base, comprising; a. a pivoting member pivotally mounted to a support member for movement of said pivoting member relative to said support member in a belt tensioning direction and an opposite belt slackening direction; and, b. means for providing a force responsive to at least one direction of pivotal movement, said means joining said support and pivoting members .

27. The motor base of claim 26 wherein said means for providing a force responsive to at least one direction of pivotal movement does so in said belt slackening direction.

28. The motor base of claim 26 wherein said means for providing a force responsive to at least one direction of pivotal movement comprises at least one shock absorber.

29. The motor base of claim 26 wherein said means for providing a force responsive to at least one direction of pivotal movement is selectively adjustable.

30. The motor base of claim 26 wherein said means for providing a force responsive to at least one direction of pivotal movement is attached between said pivoting and support members such that said pivoting member can pivotally move from a first position to a second position, and return to said first position, said means for providing a force responsive to at least one direction of pivotal movement providing cushioning force during at least a portion of the pivotal movement of said pivoting member.

31. The motor base of claim 26 wherein said pivoting member is a portion of a motor housing.

32. A motor, comprising; a. a motor housing pivotally mounted to a support member for pivotal movement relative to said support member and around a pivot axis, said movement being in a belt tensioning direction and in an opposite belt slackening direction; and b. a pivot dampening mechanism, connected between said support member and said motor housing, for providing a force in at least one direction of pivotal movement.

33. A motor base, for use with a motor used to drive a continuous belt connected to a driven device, said motor base comprising; a. a pivoting member adapted to receive a motor, said pivoting member pivotally mounted to a support member for pivotal movement of said pivoting member relative to said support member and around a pivot axis, said movement being in a belt tensioning direction and in an opposite belt slackening direction; and b. a pivot cushioning mechanism, connected between said support and pivoting members, for providing a cushioning force in at least one direction of pivotal movement.