GB2242954A - A gear for use in a gear box wherein the gear has a shoulder on each tooth - Google Patents

Abstract

A gear for use in a gear box wherein a driving face of each tooth includes a shoulder located intermediate the axial ends thereof which divides the face into a leading face and a trailing face relative to the driving direction of rotation, both the leading face and the trailing face being adapted to drive an adjacent gear, so that said adjacent gear, which is mounted to be axially movable is, when in driving engagement with the trailing face, prevented by the shoulder from moving axially to engage the leading face until the adjacent gear clears the shoulder. The gear is preferably made up of two gears joined together, one of which gears has thicker teeth than the other. <IMAGE>

Description

A GEAR FOR USE IN A GEAR BOX This invention relates to a gear for use in gear boxes and transmissions, particularly those used in winches having multiple speeds or gear ratios in one direction of drum rotation.

The present specification is divided out of our UK patent specification 2206934 which describes and claims a multispeed gear box.

According to the present invention there is provided a gear for use in a gear box wherein a driving face of each tooth includes a shoulder located intermediate the top and bottom of the gear which divides the face into a leading face and a trailing face relative to the driving direction of rotation, both the leading face and the trailing face being adapted to drive an adjacent gear, so that said adjacent gear, which is mounted to be axially movable is, when in driving engagement with the trailing face, prevented by the shoulder from moving axially to engage the leading face until the adjacent gear clears the shoulder.

Reference is now made to the accompanying drawings, in which: Figure 1 is a side view of a winch; Figure 2 is the winch of Figure 1 with the housing removed to reveal the internal gear trains; Figure 3 is a top view of the winch of Figure 2 taken along the line III-III; Figure 4 is a side view of the winch in Figure 2 taken along the line IV-IV; Figure 5 is a partial side view of the winch in Figure 2 taken along the line V-V in Figure 3 showing the relationship between the gears on the drive shaft and the traveler gear in the lower position; Figure 6 is a partial side view taken along the line VI-VI in Figure 4 of the lift mechanism positioning the traveler gear in the lower position shown in Figure 5;; Figure 7 is a partial side view taken along the line Vil-Vil of Figure 3 showing the relationship between the traveler gear in the lower position and the output gear shaft; Figure 8 is a partial side view of the winch in Figure 2 showing the relationship between the drive shaft gears and the traveler in the upper position; Figure 9 is a partial side view of the lift mechanism positioning the traveler gear in the upper position shown in Figure 8; Figure 10 is a partial side view showing the relationship between the traveler gear in the upper position and the output gear shaft, Figure 11 is a partial side view taken along the line XI-XI of Figure 3 showing the relationship between the drive shaft and the output gear shaft;; Figure 12 is a partial side view taken along the line XII-XII of Figure 3 showing the relationship between the drive shaft and the reduction gear; Figure 13 is a top view of the gear in Figure 12 taken along the line XIII-XIII; Figure 14 is a partial side view taken along the line XIV-Xlv of the drive shaft and the reduction gear shaft; and Figure 15 is a partial top view of the top drive shaft gears and the traveler gear, revealing the retaining shoulder.

The winch 1 shown in Figure 1 is adapted for manual operation; however, the winch is equally adaptable for motor-driven operation. The winch 1 comprises a base 2 and drum 3 which is rotatably supported on the base 2. Also shown is a crank 4 and a crank handle 5. The winch is provided with a receiving socket at its top to receive the end of the crank for locking rotatable connection. A line 6 is being pulled-in as shown in phantom.

Turning now to Figure 2, there is shown the base 2, the drum 3, and the internal gear housing 7. The internal gear housing 7 seats within the base 2 and is secured to the base with bolts 8. The gear housing 7 terminates at its upper end in a drive shaft sleeve 9 for housing the centrally located drive shaft A. Roller bearings 10 are positioned between the drive shaft A and the drive shaft sleeve 9.

Roller bearings 11 and 12 are positioned between the rotating drum 3 and the drive shaft sleeve 9.

The gear housing 7 supports four shafts, the drive shaft A, the traveler gear shaft B, the reduction gear shaft C, and the output shaft D. The drive shaft A carries gears Al, A2, A3, and A4, numbering from top to bottom. The traveler gear shaft B carries a traveler gear B1 which is axially movable between a lower and an upper position. The reduction gear shaft C carries two gears, C1 and C2, numbered from top to bottom. Finally, the output gear shaft D carries three gears, D1, D2 and D3 from top to bottom, with Dl. being the output drive gear which meshes with the drum's internal ring gear 13.

The winch 1 shown in the drawings has three speeds or gear trains. The first and third speeds are respectively determined by the position of the traveler gear B1. First speed is achieved when gear B1 is in the up position as shown in Figure 8 and meshes with gear Al and gear D2.

The gears on each shaft are connected to their respective shafts as follows. Gears Al and A2 are unidirectional gears, meaning that in the preferred embodiment they will rotate directly with the shaft when the shaft is rotated in the clockwise direction. In other words the shaft, when rotating clockwise transfers its rotational power to gears Al and A2. However, by means of a ratchet and pawl mechanism or other unidirectional mechanism, known to the art, when the shaft A rotates counterclockwise, it does not transfer power to the gears Al and A2. Gear A3 is unidirectional and only turns with the drive shaft A when the shaft rotates in a counterclockwise direction. When the shaft A rotates in a clockwise direction, gear A3 is free to rotate subject to whatever power input it receives from another gear.Gear A4 on drive shaft A is fixed to the shaft and rotates directly with the shaft in either direction.

Turning now to traveler gear shaft B and gear B1, this gear rotates freely about shaft B and only rotates subject to the power input it receives from other gears.

Reduction gear shaft C carries two gears, C1 and C2.

Gear C1 is free to rotate in either direction around the shaft subject to the input of other gears. Gear C2 is unidirectional and will be driven by gear C1 when C1 rotates counterclockwise, and is free from C1 when gear C1 rotates clockwise. In that event, gear C2 is driven by other gears.

Gear C2 will drive gear C1, when it rotates counterclockwise.

The output gear shaft D carries three gears, Dl, D2 and D3. The gear D1 is the output drive gear and it meshes with the internal ring gear 13 integrally affixed to the inside rim of the drum 3. It is understood that although a winch is utilised the gear box described could be utilised to drive a variety of outputs. The gear D1 is freely rotatable about the output gear shaft D; however due to the design and relationships of all the shafts, gears, and gear trains, the output gear D1 always rotates in the same direction regardless of which direction the drive shaft A is rotated, which is clockwise in the embodiment described herein. The clockwise rotation of the output gear D1 will accordingly cause the drum to rotate in a clockwise direction.It will be apparent to those skilled in the art that in many situations it could be desirable to have the drum rotate in a counterclockwise direction, and the winch can be simply and easily modified using the same parts to accomplish this result, such as by merely reversing the orientation of the unidirectional mechanisms.

Gear D2 is integral with output drive gear D1 and has a sleeve 14 which extends down and around the output gear shaft D and provides the internal shaft collar 15 for gear D3. The gear D3 is mounted on the shaft D through a unidirectional pawl and ratchet mechanism 16 shown in Figure 7.

The function of gear D3 and its pawl and ratchet mechanism 16 is to transfer power from gear D3 to the output drive gear D1 when the gear D3 is driven in a clockwise direction.

When the gear D3 is driven counterclockwise relative to its internal shaft collar 15, the gear rides over the pawls and is disengaged from gears D2 and D1. Also when gear D2 is driven, the internal shaft collar 15 rotates at a speed faster than gear D3 thus effectively overriding the gear D3.

FIGS. 5-10 illustrate the operation of the traveler gear lift mechanism 20. In FIG 6, it is shown that the lift mechanism 20 is fixedly attached to the gear housing 7 via a stationary arm 21. At the distal end of the stationary arm 21, a cam-operated lever 22 is pivotally supported. at 23. The lever 22 comprises a cam follower 24 and a lift arm 25. The cam follower 24 and the lift arm 25 are independently pivoted at 23. The cam follower 24 is provided with a perpendicular extension 26 in which is mounted an adjustment screw 27 whose terminal end abuts the bottom of lift arm 25 in order to define the angular relationship between the cam follower 24 and the lift arm 25. The adjustment screw 27 provides continuous adjustment for the lift arm 25.

The lift arm 25 comprises a semi-circular stirrup member 28 with internally extending pins 29. The pins 29 are retainingly received in the circular channei 31 of collar 30 which is integral with traveler gear B1. In other embodiments, the collar could be separate from the gear Bi.

The purpose and benefit of having cam follower 24 and lift arm 25 independently pivoted at 23 is that when collar 30 is integrally attached to the traveler gear B1, it allows the lift mechanism 20 to be moved to its lower position and to leave the traveler gear B1 in its upper position, as described hereinafter. In the alternative, if it were desired to have cam follower 24 and lift arm 25 fixed to one another at a fixed angle, then it would be preferable to separate the collar 30 from the gear B1 so that they are separately movable on the shaft B.

The traveler gear lift mechanism 22 includes a controller mechanism which allows the winch operator to position the traveler gear B1 in either the up or down position. The controller mechanism includes a rotatable cylindrical knob 40 which extends externally from the base 2 and is adapted to be manually rotated in any direction. A cam 41 is integrally affixed to the distal end of the knob 40. The knob 40 is housed in a cylindrical knob housing 42. Manual rotation of the knob 40 moves the cam 41 which in turn moves the cam follower 24. In one cam position the traveler gear B1 is in the up position as seen in FIGS. 8, 9, and 10, and in an other position, the traveler gear B1 is in the lower position as seen in FIGS. 5, 6, and 7.

Also seen in FIGS. 5-10 is a spring 19 which is positioned around shaft B above gear B1 between the housing 7 and the gear B1. This spring 19 serves to bias the gear B1 downwardly. The use of such a biasing means eliminates the need to rely on gravity to move gear B1 down, and thus permits the winch to operate in any orientation.

Although the embodiment of the lift mechanism 20 shown in the drawing is the- preferred embodiment, it will be recognized by those skilled in the art that other embodiments of a gear lift mechanism are possible and included in the term lift mechanism.

Now will follow a description of how the winch can be operated in three speeds, as well as in any combination of two speeds.

The winch is operated in the first speed by moving the traveler gear B1 to the upper position, and then rotating the drive shaft A in the clockwise direction.

As discussed above, in the arrangement of this embodiment, the drum 3 will rotate at a fast speed in the clockwise direction. This fast rotational speed provides the smallest mechanical advantage and is useful when the line load is small and it is desirable to pull in the line as quickly as possible.

The first speed is obtained through the following gear train. The drive shaft A rotates clockwise which through the unidirectional mechanism in gear Al drives gear Al clockwise. Gear Al driyes gear B1 in a counterclockwise direction. Gear B1 drives gear D2 in a clockwise direction. Since gear D2 and D1 are integral, gear D1 will also rotate in a clockwise direction. Gear D1 is the output drive gear and it will drive the drum, through the ring gear 13, in a clockwise direction at the fastest speed.

The second speed is activated by reversing the direction of rotation of the drive shaft. Because gears Al and A2 are unidirectional, they will no longer drive gear B1. However, gear A3, a unidirectional gear, is driven in a counterclockwise direction and will in turndrive unidirectional gear D3 in a clockwise direction.

Gear D3 will drive output gear D1 in a clockwise direction which drives the drum in a clockwise direction. The second speed is a medium speed which provides a greater mechanical advantage than the first speed, and accordingly a slower drum rotation speed for a given drive shaft rotation speed.

If the traveler gear is held in its upper position in engagement with the first speed gear train, a second reversal of the drive shaft to a clockwise rotation will return the winch to the first speed. This arrangement will allow the winch to operate between first and second speed only upon successive reversals of drive shaft rotation. However, if during the operation of the winch in second speed, it is desired to switch to third speed, the traveler gear lift mechanism is operated to lower the traveler gear B1 to its lower position. This disengages the gear B1 from the first speed gear train (i.e., 31 from D2). Then upon the second reversal of rotation of the drive shaft back to a clockwise rotation, the third speed is engaged.

The third speed is obtained as follows. Shaft A rotates in a clockwise direction which drives gear A4 in a clockwise direction. Gear A4 drives unidirectional gear C2 in a counterclockwise direction. Gear c2, through shaft C, drives gear C1 in a counterclockwise direction. Gear C1, in turn, drives gear D3 in a clockwise direction which through shaft D drives output drive gear D1 clockwise which causes the drum 3 to rotate clockwise.

If desired, the winch can be operated between second and third speeds only by leaving the traveler gear B1 in its lower position, and by first rotating the drive shaft counterclockwise for second speed operation and then reversing the drive shaft rotation to clockwise rotation for third speed operation. Successive reversals of the drive shaft rotation will shift the winch speed back and forth from second to third.

An additional feature of the preferred winch is provided by the construction and design of gears Al and A2. As shown in FIG. 15, gears Al and A2 have the same pitch (i.e., same number of teeth); however, the gear teeth on gear A2 are thicker. The respective teeth on gears Al and A2 are arranged such that in the preferred embodiment, the counterclockwise-facing sides of the teeth on gears Al and A2 are flush, whereas the clockwise-facing surfaces of the gear teeth are not flush, the thicker teeth of gear A2 provide a small leading shoulder 18.In operation, when the traveler gear B1 is in its upper position and the drive shaft is being rdtated in a clockwise direction, the shoulder 18 provided by the thicker teeth on gear A2 will retain the traveler gear B1 in its upper position and prevent 'it from moving down to the lower position while the gears are being rotated. It will be appreciated that the width of the shoulder 18 is made sufficient to avoid accidental displacement of the traveler gear B1, and a shoulder width of about 1-2 millimeters will prevent most accidentical displacements. See FIG. 15.It can be seen that if it is desired to have the traveler gear B1 move down to its lower position out of engagement with the first speed gear train, the traveler gear lift mechanism is raised to lift the traveler gear B1 to its upper position. There, a slight rotation of the drive shaft in the clockwise direction will position the shoulder 18 beneath the traveler gear B1 so as to retain the gear B1 in the upper position. The lift mechanism can then be lowered without traveler gear B1 being lowered, and the traveler gear B1 is now set for automatic shifting to its lower position by any counterclockwise rotation of the drive shaft such that the shoulder 18 is removed from underneath the gear Bl.

It is preferable, to form gears Al and A2 separately, and to provide guide pin holes through both gears Al and A2 to receive guide pins 17 which will properly align the gear teeth so that the shoulder is properly positioned for clockwise first speed rotation.

If it is desirable to have the drum rotate counterclockwise or to provide counterclockwise first speed rotation, a second set of guide pin holes can be provided in the gears Al and A2 to position the retaining shoulder on the other side of the gear tooth space.

In essence the gear A2 can be replaced by a lip extension at the same location at the bottom of the gear Al tooth space, in view of the fact that gear A2 serves no driving function. However, it is preferred to provide gear A2 with or without the retaining shoulder or lip because although. it may be a "dummy gear", it serves a guiding function. It serves a guiding function in that the gear A2 meshes with the teeth in gear B1 and thus times the gear B1 to synchronize the smooth upward movement back into engagement with gears Al and D2.In other words, if it were desired not to provide the shoulder 18 or lip to retain the traveler gear B1 in its upper position without the aid of the lift mechanism 20, it would still be desireable to provide gear A2 having teeth which were completely flush with the teeth of gear Al to provide the timing and synchronization function.

In such a case the gear Al and gear A2 would in reality be one axially long gear whereby when traveler gear B1 is in its upper position meshing with the top portion of the gear Al, the first speed gear train would be engaged, and when traveler gear B1 is in its lower position meshing with the lower portion of gear Al, gear B1 would be out of engagement with the first speed gear train.

It will be appreciated from the above that this winch will operate at three speeds upon two reversals of the drive shaft rotation. If desired, the winch can be operated as a two speed winch, alternating between the first and second speeds, the first and third speeds, or the second and third speeds.

To operate the winch between only the first and second speeds, one merely has to leave the traveler gear lift mechanism in the upper position so that upon a second reversal of drive shaft rotation, the winch returns to first speed operation.

To operate the winch between only second and third speeds, the traveler gear mechanism is placed in the lower position so that the traveler gear B1 never is placed in the upper first speed position in engagement with the first speed gear train. Then, the drive shaft is first rotated counterclockwise to operate the winch in second speed and upon a first reversal of the drive shaft, the winch will be in third speed; and then upon a second reversal, the winch will return to its second speed.

In order to operate the winch in first and third speeds only, the winch is operated as if for normal first, second, and third speed operation; however, upon completion of first speed operation, the winch is placed in third speed without reversal of the rotation of the drive shaft and passing through second gear by stopping the rotation of the center drive shaft and allowing the traveler gear 31 to drop into its lower position.

Depending on the design of the gears, and the width of the shoulder, it may require a small amount of back and forth movement to facilitate the dropping of the traveler gear B1.

It should be understood that although a preferred embodiment has been disclosed other embodiments obvious to those skilled in the art could be designed.

Claims (4)

1. A gear for use in a gear box wherein a driving face of each tooth includes a shoulder located intermediate the top and bottom of the gear which divides the face into a leading face and a trailing face relative to the driving direction of rotation, both the leading face and the trailing face being adapted to drive an adjacent gear, so that said adjacent gear, which is mounted to be axially movable is, when in driving engagement with the trailing face, prevented by the shoulder from moving axially to engage the leading face until the adjacent gear clears the shoulder.

2. The gear according to Claim 1, wherein the gear is comprised of two conventional gears having the same number of teeth and positioned one on top of the other, the teeth of one gear are thicker than the teeth of the other, and means for aligning the two gears so that the thicker teeth of the one gear forms the shoulder of the leading face.

3. The gear according to Claim 1, further including a second gear which is in driving engagement with the first gear and is mounted to be axially movable relative to the first gear so that it can be alternately driven by the leading face or the trailing face of the first gear.

4. The gear according to Claim 1, wherein the gear is made entirely of the same material.