Gear Reducing Device

1. Field of the Invention

This invention relates to gear reducing devices and more particularly, to a gear reducing device for application in sawmills and the like, which device is characterized by an input drive system and an output drive system located in a chamber or housing and separated by a rotating disc. The input drive system of the gear reducing device includes an input shaft having one end rotatably seated in axial alignment in one end of an output shaft and extending from the housing and driven by an electric motor and belt combination. A spur and pinion gear is secured to or shaped integrally with the input shaft and engages a pair of oppositely-disposed, larger input spur gears, each of which is provided with a fixed auxiliary spur gear, which input spur gears and auxiliary spur gears are rotatably mounted in spaced relationship on the disc. The auxiliary spur gears mesh with an output shaft spur gear that is keyed to the output shaft, which rotates independently of the input shaft, and, together with the input spur gears, drive the disc. The auxiliary spur gears are rotatably mounted along with the input spur gears, respectively, on a pair of auxiliary spur gear shafts which are press-fitted in spaced relationship along a diameter of the rotating disc, which is rotatably mounted on the output shaft. Accordingly, rotation of the input shaft at a selected speed effects planetary rotation of the input spur gears on the spur and pinion gear and the auxiliary spur gears on the output shaft spur gear. This rotation of the input spur gears around the spur and pinion gear also effects rotation of the disc on the output shaft in the opposite direction from the direction of rotation of the input shaft.

The output drive system of the gear reducing device includes an output spur gear keyed to the output shaft, a fixed gear spaced from the output shaft sprocket and mounted in fixed relationship to the housing and a pair of double spur gears rotatably mounted on the disc in spaced relationship and along a diameter in ninety degree disposed relationship with respect to the auxiliary spur gears, respectively. The fixed gear engages a common set of teeth in the double spur gears and the output spur gear engages an adjacent set of teeth in the double spur gears, respectively. Accordingly, rotation of the disc by operation of the input drive system effects rotation of the output spur gear and the output shaft, since the output spur gear is keyed to the output shaft. Rotation of the double spur gears drives the output shaft at a speed which is determined by the respective gear ratios of the spur and pinion gear, input spur gears, auxiliary spur gears, output shaft spur gear, output spur gear, fixed gear and double spur gears, respectively. The torque applied to the output shaft depends upon the relative number of teeth provided on the fixed gear and output spur gear, respectively, located in the output drive system.

2. Description of the Prior Art

Various devices are known in the art for achieving a mechanical advantage in gearing, power transmission, speed reduction and the like. Early U.S. Pat. No. 846,086, dated Mar. 5, 1907, to G. E. Bouvier, et al, entitled "Gearing", details a differential driving connection for decreasing the speed of bobbins in a fly-frame as the bobbins are filled and increased in diameter, in order to assure that the yarn on the bobbin will be wrapped with a desired degree of tension. U.S. Pat. No. 2,140,790, dated Dec. 20, 1938, to I.R. Davis, is entitled "Power Transmission". The power transmission mechanism is designed to develope maximum power using a pair of bevel gears coupled to a system of spur gears. U.S. Pat. No. 2,210,598, dated Aug. 6, 1940, to R. K. Pepper, et al, details a "Power Clutch Unit" adapted for use in connection with heavy duty, slow speed mechanisms such as Caterpillar tractors, power-operated shovels, trucks and the like. U.S. Pat. No. 2,312,908, dated Mar. 2, 1943, to F. R. Ibanez, details a "Mechanism for Transmitting Power" which includes chain-connected sprockets and meshing gears for speed reduction purposes. "Variable-Speed Gearing" is detailed in U.S. Pat. No. 2,582,620, dated Jan. 15, 1952, to G. Colucci. The device includes one pair of variable diameter pulleys driven by a V-belt or chain, where the tension is maintained in the chain or V-belt by the centrifugal force generated by rotation of the pulley system mounted on shafts carried by supports articulated to the axis of rotation of the pulley system. U.S. Pat. No. 2,653,490, dated Sept. 29, 1953, to E. Testori, details a "Progressive Variable Speed Drive Capable of Reverse Rotation". The system includes meshing gears and a V-belt and is designed to provide a progressive variable speed drive, by which it is possible to reach zero speed on the driven shaft while the driving shaft rotates at a selected speed. Reversal of the direction of rotation is also possible with the system. U.S. Pat. No. 3,130,608, dated Apr. 28, 1964, to L. H. Moran, details a "Chain-Type Speed Reducer" for transmitting power between rotatable members of the reducer and materially reducing the drive from a drive shaft to a driven shaft. The reducer employs a lever driven by the drive shaft for operating chains or the like circumferentially around a fixed sprocket to reduce the speed of the driven shaft. A "Variable Speed Power Transmission for Small Vehicles and the Like" is detailed in U.S. Pat. No. 4,048,871, dated Sept. 20, 1977, to N. G. Fyock. The transmission system includes primary and secondary transmissions connected in series, wherein a forward speed having a variable output depends upon the load placed on the input shaft to the primary transmission. The secondary transmission functions in one mode to reverse the direction of the output shaft, while the primary transmission operates to provide a variable gear ratio, depending upon the load placed upon the input shaft to the primary transmission. Other patents of interest are U.S. Pat. No. 2,122,330 dated June, 1938, to Stenzy; U.S. Pat. No. 4,044,633 dated August, 1977, to Lee; U.S. Pat. No. 3,979,971, dated September, 1976, to Generke, et al; U.S. Pat. No. 3,429,200, dated February, 1969, to Green; and U.S. Pat. No. 2,197,014, dated April, 1940, to Stenzy.

It is an object of this invention to provide a gear reducing device which utilizes an input shaft rotatably seated in one end of an output shaft, meshing input gears engaging the input shaft and output shaft on the input side of a rotating disc, and meshing output gears having a different number of teeth, connected to the output shaft on the opposite or output side of the disc, to create a mechanical advantage at the output shaft.

Another object of this invention is to provide a gear reducing device which utilizes an input shaft rotatably and linearly terminating in an output shaft coupled to a system of input gears located on the input side of a heavy disc or flywheel, to define an input drive system and output gears having a different number of teeth and located on the opposite side of the flywheel to define an output system, for driving the output shaft at a selected speed and torque.

Yet another object of this invention is to provide a gear reducing device which is characterized by an input drive mechanism having an input shaft carrying a spur and pinion gear that meshes with a pair of matching, oppositely-disposed input spur gears and auxiliary spur gears which are, in turn, rotatably attached to a rotating disc and mesh with an output shaft spur gear keyed to an output shaft rotatably receiving the input shaft in axial alignment. The output drive mechanism includes a pair of spaced double spur gears rotatably mounted on the disc and engaging an output spur gear having a first selected number of teeth and keyed to the output shaft and a fixed gear having a second selected number of teeth and secured to the housing of the gear reducing device, respectively, for creating low speed, high torque operation of the output shaft.

A still further object of this invention is to provide a new and improved gear reducing device which is characterized by a housing, all input shaft carrying a spur and pinion gear and journalled for rotation in one end of the housing and an output shaft journalled for rotation in the opposite end of the housing, one end of which input shaft is rotatably and axially seated in a corresponding end of the output shaft, and further including a disc or flywheel rotatably mounted on the output shaft and fitted with a pair of auxiliary spur gears for meshing with an output shaft spur gear keyed to the output shaft and a pair of input spur gears meshing with the spur and pinion gear, for driving the disc at a speed proportional to the speed of the input shaft. The disc is further provided with a pair of double spur gears engaging an output spur gear keyed to the output shaft and a fixed gear having a different number of teeth from the output spur gear and located on the output side of the disc, to determine the output shaft torque.

These and other objects of the invention are provided in a new and improved gear reducing device which is characterized in a preferred embodiment by a cylindrical housing having an input shaft journalled for rotation in one end and an output shaft journalled for rotation in the opposite end, which input shaft is rotatably and linearly seated in one end of the output shaft; a disc rotatably mounted on the output shaft; a spur and pinion gear mounted on the input shaft and meshing with oppositely-disposed input spur gears rotatably mounted along with a pair of auxiliary spur gears, on a pair of input spur gear shafts which are press-fitted into the disc in spaced relationship. The auxiliary spur gears are, in turn, meshed with an output shaft spur gear keyed to the output shaft, to complete an input drive system for effecting a rotational speed of the disc which is proportional to the rotational speed of the input shaft. The torque-producing output drive system of the gear reducing device is characterized by a pair of double spur gears rotatably mounted on the rotating disc in spaced, 90 degree disposed relationship with respect to the auxiliary spur gears and engaging an output spur gear having a first selected number of teeth and keyed to the output shaft, and a fixed gear having a second selected number of teeth and bolted to the gear reducing housing, respectively. Operation of the input shaft at a selected rotational speed effects rotation of the disc, the output spur gear and the output shaft at much reduced speeds, with a torque which is determined by the respective number of teeth located on the fixed gear and the output spur gear.

The invention will be better understood by reference to the accompanying drawings, wherein:

FIG. 1 is a front view, partially in section, of a preferred embodiment of the gear reducing device of this invention;

FIG. 2 is a rear view of the gear reducing device illustrated in FIG. 1, with the rear housing removed;

FIG. 3 is a sectional view taken along line 3--3 of the gear reducing device illustrated in FIG. 1;

FIG. 4 is a partial sectional view taken along line 4--4 of the gear reducing device illustrated in FIG. 2; and

FIG. 5 is an exploded simplified view of the gear reducing device illustrated in FIGS. 1-3.

Referring initially to FIGS. 1 and 4 of the drawings, the gear reducing device of this invention is generally illustrated by reference numeral 40. The gear reducing device 40 includes a cylindrical housing 1, fitted with an optional lifting hook 36 on the top thereof and enclosed at the front by an input cover plate 2 and at the rear by an output cover plate 4. Gaskets 33 serve to seal the input cover plate 2 and the outplate cover plate 4 on the housing 1, in order to enclose a pool of oil 44 in the lower portion of the housing 1. A base 39 is mounted on the lower portion of the housing 1 to maintain the gear reducing device 40 in an upright position, as illustrated. As further illustrated in FIG. 1, an oil filler plug 41 is threadably seated in the housing 1 for introducing the oil 44 into the housing 1. In a preferred embodiment of the invention the circular facing edges of the housing 1 are fitted with internally-threaded cover plate bolt apertures 34a, for receiving corresponding cover plate bolts 34 and removably securing the input cover plate 2 and the output cover plate 4 on opposite ends of the housing 1. An input shaft 11 is journalled for rotation in the input cover plate 2 of the housing 1 and extends through a pair of input shaft bearings 3, located in a bearing housing 3a, as further illustrated in FIG. 4. A snap ring 18 seats in a groove (not illustrated) provided in the input shaft 11 for rotatably securing the input shaft, 11 in the bearing housing 3a. Bearing housing bolts 3b serve to maintain the bearing housing 3a in position on the input cover plate 2 and protect the spaced input shaft bearings 3. The output cover plate 4 located on the opposite end of the housing 1 includes a projecting center portion which rotatably receives an output shaft 20, extending through an output shaft bearing 5, as illustrated in FIG. 3. A cover plate 4a closes the front end of the center portion projection and plate bolts 4b serve to removably secure the cover plate 4a on the projecting portion of the output cover plate 4, as further illustrated in FIG. 4. An output shaft key 20a is seated in the extending portion of the output shaft 20 for coupling a load (not illustrated) to the output shaft 20 in driving relationship.

As further illustrated in FIG. 3, an oil drain plug 43 is threadably seated in the lower portion of the input cover plate 2 for draining the oil 44 from the housing 1. Furthermore, an electric motor 7 is illustrated in phantom in close proximity to the housing 1 and includes a motor shaft 7a, which receives a motor shaft sheave 8. An input shaft sheave 10 is aligned with the motor shaft sheave 8 and fastened to the extending end of the input shaft 11 by means of an input shaft key 11a and a belt 9 connects the input shaft sheave 10 to the motor shaft sheave 8, as further illustrated in phantom in FIG. 3. Accordingly, operation of the electric motor 7 at a selected speed drives the input shaft 11 at a corresponding speed to operate the combination chain and gear reducing device.

Referring again to FIGS. 1, 3, 4 and 5 of the drawings, the input drive system of the gear reducing device 40 is characterized by a spur and pinion gear 12 having 16 teeth and secured to or formed integrally with the input shaft 11 inside the housing 1. An input shaft extension 31 defines that portion of the input shaft 11 which projects beyond the spur and pinion gear 12 and extends axially into a shaft extension bushing 32, provided in the output shaft 20, as hereinafter further described. A pair of input spur gears 13, each having 96 teeth adapted for meshing with the teeth on the spur and pinion gear 12, are engaged with the spur and pinion gear 12 in oppositely-disposed relationship, as further illustrated in FIG. 4. Each of the input spur gears 13 is rotatably mounted on a separate spur gear shaft 14 by means of a shaft clip 23, the opposite ends of which spur gear shafts 14 are press-fitted into corresponding shaft openings 35 of a rotating disc 16, which is, in turn, rotatably mounted on the output shaft 20 by means of a disc bearing 21. A separate auxiliary spur gear 15 is welded by means of welds 37, or otherwise attached to or integrally formed with, each of the input spur gears 13 between the input spur gears 13 and the rotating disc 16, as further illustrated in FIG. 4. Each of the auxiliary spur gears 15 is characterized by 44 teeth, which teeth mesh with corresponding teeth in the output shaft spur gear 19, attached to the output shaft 20 by means of a spur gear key 19a. In a preferred embodiment of the invention the output shaft spur gear 19 has 40 teeth adapted for meshing with the 44 teeth of the auxiliary spur gears 15 in driving relationship. Accordingly, from a consideration of the input drive system of the gear reducing device 40, it can be seen by reference to FIGS. 1, 4 and 5 that rotation of the input shaft 11 at a speed determined by the electric motor 7 and the relative sizes of the motor shaft sheave 8 and input shaft sheave 10, also rotates the spur and pinion gear 12, which causes the input spur gears 13 to traverse the spur and pinion gear 12 in oppositely-disposed, planetary fashion. This planetary motion of the input spur years 13 in concert causes the auxiliary spur gears 15 to rotate and traverse the output shaft spur gear 19 and this effects rotation of the rotating disc 16 in the opposite direction from the direction of rotation of the input shaft 11. For example, if the number of teeth provided on the output shaft spur gear 19 is the same as the number of teeth on the auxiliary spur gears 15, then the rotating disc 16 rotates one revolution for each revolution of both the output shaft spur gear 19 and the auxiliary spur gears 15. Accordingly, it is understood that the respective gear ratios provided in the spur and pinion gear 12, the input spur gears 13, the auxiliary spur gears 15 and the output shaft spur gear 19 determine the rotational speed of the rotating disc 16. Furthermore, it is also apparent that the resulting rotational speed of the output shaft 20 is much less than that of the input shaft 11, as further hereinafter described.

The output drive system of the gear reducing device 40 is detailed in FIGS. 2, 3 and 5 of the drawings and is designed to determine the torque of the output shaft 20. FIGS. 2 and 3 more particularly illustrate an output spur gear 29 having 20 teeth and fixedly attached to the output shaft 20 by means of an output shaft key 30, as illustrated in FIG. 3. Furthermore, a fixed gear 6, leaving 21 teeth, is attached to the output cover plate 4 of the housing 1 by means of gear mount bolts 6a, which extend through corresponding mount bolt apertures 6b, provided in the fixed gear 6, as more particularly illustrated in FIGS. 2 and 5. The fixed gear 6 is provided with a fixed gear bushing 17 for rotatably receiving the output shaft 20, as illustrated in FIG. 3. A pair of double spur gears 24 are mounted by means of double gear bushings 25 on a pair of double spur gear shafts 22 across a diameter of the rotating discs 16, in 90 degree relationship with respect to the auxiliary spur gears 15, respectively. Each of the double spur gears 24 is characterized by four pins 26, which strengthen the split, dual gear elements of the double spur gears 24. Twenty-one front teeth 24a are positioned in spaced relationship on the front segment of each double spur gear 24 and each double spur gear shaft 22 is press-fitted in corresponding shaft openings 35 in the rotating disc 16, as further illustrated in FIG. 3. The 21 front teeth 24a located on each front segment of each double spur gear 24 are positioned in engagement with the teeth of the output spur gear 29, which are 20 in number, while the 20 rear teeth 24b provided on the rear segment of each double spur gear 24 are engaged with the 21 teeth on the fixed gear 6. The rear teeth 24b of the rear segment of the double spur gears 24 thus engage correspondingly aligned teeth in the fixed gear 6, as further illustrated in FIGS. 2 and 3. Similarly, the front teeth 24a of the front segment of the double spur gears 24 engage the correspondingly aligned teeth in the output spur gear 29, as illustrated in FIG. 3. Accordingly, it will be appreciated that rotation of the rotating disc 16 at a speed determined by the rotational speed of the input shaft 11 and the respective gear ratios of the input spur gears 13, auxiliary spur gears 15 and output shaft spur gear 19, causes the output spur gear 29 and the output shaft 20 to rotate at a reduced speed, driven by the double spur gears 24. This output shaft rotation is effected at a specified torque as the rear teeth 24b and the front teeth 24a in the double spur gears 24 engage and traverse the corresponding teeth (which are unequal in number) in the fixed gear 6 and output spur gear 29, respectively.

Referring again to FIGS. 1, 3, and 5 of the drawings, as the input shaft 11 is viewed from the front and is driven in the counterclockwise direction by the electric motor 7, the motor shaft sheave 8, input shaft sheave 10 and belt 9, illustrated in FIG. 3, and the spur and pinion gear 12 rotate in the counterclockwise direction, as indicated by the arrow. Counterclockwise rotation of the input shaft 11 and the spur and pinion gear 12 causes the input spur gears 13, the teeth of which are engaged with the teeth of the spur and pinion gear 12, to rotate in the clockwise direction, as further illustrated by the arrows in FIG. 5. Since the two auxiliary spur gears 15 are fixed to the spur gears 13, respectively, and are mounted on the spur gear shafts 14, the auxiliary spur gears both also rotate on the spur gear shafts 14 in the clockwise direction, with the input spur gears 13, respectively. Furthermore, the auxiliary spur gears 15 engage the output shaft spur gear 19 on opposite sides and rotate in concert around the output shaft spur gear 19. Moreover, as heretofore described, the auxiliary spur gears 15 are rotatably mounted with the input spur gears 13 on corresponding spur gear shafts 14, the ends of which are rigidly seated in spaced shaft openings 35, located along a common diameter in the rotating disc 16. As further heretofore described, the rotating disc 16 is rotatably mounted on the output shaft 20 by means of a disc bearing 21 and rotates along with the auxiliary spur gears 15, which rotate in a clockwise path with the input spur gears 13, about the input shaft 11 and input shaft extension 31. This clockwise rotation of the rotating disc 16 also effects counterclockwise rotation of the spaced double spur gears 24, since the double spur gears 24 engage the output spur gear 29 and fixed gear 6, respectively. The output spur gear 29 thus also rotates in the clockwise direction to drive the output shaft 20, since the former is keyed to the latter, while the fixed gear 6 is bolted to the output cover plate 4. A desired torque is created in the rotating output shaft 20 by providing a different number of teeth in the output spur gear 29 and fixed gear 6, as heretofore described. By way of example, the output spur gear 29 has 20 teeth, while the fixed gear 6 is provided with 21 teeth, which disparity creates a most preferred torque in the output shaft 20.

It will be appreciated from further consideration of FIGS. 3 and 5 that the double spur gears 24 must each contain the same number of front teeth 24a and rear teeth 24b on the respective front and rear segments, respectively, since the front teeth 24a and rear teeth 24b of the double spur gears 24 engage both the teeth of the output spur gear 29 and fixed gear 6, respectively, and this gear ratio is a significant factor in determining the desired torque at the output shaft 20. Accordingly, for each revolution on the fixed gear 6, the double spur gear 24 rotates one revolution on the double spur gear shaft 22. Furthermore, the output spur gear 29 must have more or less teeth, and more preferably, one more or one less tooth, than the fixed gear 6, as described above, in order to effect the desired torque on the output shaft 20 as the gear reducing device 40 operates. Consequently, by way of example, if the output spur gear 29 has 20 teeth and the fixed gear 6 has 19 teeth, then the output spur gear 29 will rotate in the clockwise direction at a speed proportional to the counterclockwise rotational speed of the input shaft 11 and rotating disc 16 and with an optimum torque which is proportional to the difference in the number of teeth located on the output spur gear 29 and the fixed gear 6. Considering the gear reducing device 40 illustrated in the drawings and having the gear components described above, the motor shaft sheave 8 and input shaft sheave 10 are chosen such that the 1750 rpm rotation of the motor shaft 7a causes the input shaft 11 to rotate at a speed of 437 rpm. This causes the rotating disc 16 to turn at a proportional speed and the output shaft 20 to turn at a speed of 4.5 rpm at high torque. If the number of teeth provided on the output spur gear 29 and fixed gear 6 are increased to 40 and 39, respectively, then the speed of the output shaft 20 drops to 2.25 rpm, with increased torque. Similarly, the output shaft torque can be adjusted by varying the number of teeth on the auxiliary spur gears 15 and output shaft spur gear 19, which are engaged, as illustrated in FIG. 4. Typical gear teeth numbers for the engaged auxiliary spur gears 15 and output shaft spur gear 19 are as follows, in non-exclusive particular:

Referring again to FIGS. 1-4 of the drawings, in another preferred embodiment of the invention a series of oil drip tips 45 are provided in the top of the housing 1. The level of oil 44 in the housing 1 is maintained such that the input spur gears 13 and a portion of the double spur gears 24 are periodically dipped into the oil 44. This oil is splashed onto the oil drip tips 45 and drips into the various components of the gear reducing device 40 during operation.

While the preferred embodiments of the invention have been described above, it will be recognized and understood that various modifications may be made in the invention and the appended claims are intended to cover all such modifications which may fall within the spirit and scope of the invention.