Gear reducer with tandem drives to the output

A cone drive, high output speed reducer, having a low clearance for low profile applications. An input shaft drives a helical idler pinion which in turn drives two other helical idler pinions. The two other idler pinions are each mounted on a separate shaft carrying a cone drive worm. The two worm shafts turn in unison, and the worms are each meshed with a separate worm gear. The two worm gears are operatively mounted on an output shaft. One of the helical idler pinions is provided with an adjustment means for equalizing the load sharing. That is, to provide equal loads on each of the helical pinions for load sharing throughout the twin drive gearing units of the speed reducer. The speed reducer may be provided with either an air cooling system or a water cooling system.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to gear reducers, and more particularly, to a cone 
drive, low clearance, high output speed reducer. The invention is 
specifically concerned with speed reducers for applications requiring 
unusually low profile, along with high horsepower and output torque 
capacity, such as applications in coal mining equipment wherein the 
requirements of coal mining are such as to call for the lowest possible 
profile in such equipment. 
2. Description of the Prior Art 
It is well known in the speed reducer art to employ means for transmitting 
power from a driving element to a driven element through a plurality of 
intermediate gear units, with each gear unit transmitting a portion of the 
power or taking a portion of the load. Examples of such prior art speed 
reducers are disclosed in U.S. Pat. Nos. 1,499,617, 2,014,138 and 
3,338,109. A disadvantage of the aforecited prior art speed reducers is 
that they have a high profile in order to employ the necessary gearing to 
provide a high horsepower output. A further disadvantage of the prior art 
speed reducers is that they have not satisfactorily solved the problem of 
equally dividing or sharing the load between plural intermediate gear 
units. One prior art structure for solving the load sharing problem 
involves the use of specially designed torsionally resilient shafts, or 
some form of torsionally resilient coupling. Another prior art 
construction for this purpose includes a special rocker mechanism for 
producing relative movement between intermediate gears or elements to take 
up the slack or backlash between the gears. However, such previous 
constructions are complicated and expensive and are not durable or 
reliable for heavy loads. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, the cone twin drive speed reducer 
utilizes one input shaft and two gear sets which concentrate and convey 
the combined torque into a single output shaft. The speed reducer is 
provided with internal structural provisions for equalizing or sharing the 
load between the two gear sets. 
The input shaft is adapted to be operatively connected to a suitable 
electric drive motor. The input shaft drives a helical idler drive pinion 
which in turn drives a pair of meshing helical idler driven pinions. There 
is no ratio change between the drive and driven pinions. The input shaft 
and idler pinions are operatively mounted in a suitable housing in which 
is also mounted a pair of cone drive worms operatively mounted on suitable 
shafts supported in the housing. The cone drive worm shafts are mounted in 
the left and right side of the housing and are driven in synchronism, and 
they are in turn respectively meshed with a pair of gears that are fixedly 
mounted on an output shaft which is operatively mounted in the housing. 
The axis of rotation of the input shaft is parallel to the axes of 
rotation of the two worm shafts. The output shaft is disposed at right 
angles to the axis of rotation of the two worm shafts and can be 
selectively extended through either side of the housing. 
The overall input torque applied to the input shaft results in a 
distribution of torque through the two worm shafts to the two gears on the 
output shaft, where it is recombined into the output shaft. A problem that 
is inherent in situations where power is split between two flow paths is 
in trying to get both halves of the drive unit to share the load. If the 
two gear sets are not equally loaded, that is, if one is slightly ahead of 
the other in terms of position, then it will take most, if not all of the 
load, and the other gear set will simply trail along. In order to overcome 
this problem of load sharing, the twin drive speed reducer of the present 
invention is provided with an adjustment means which is built into one of 
the helical idler driven pinions, and which allows this idler pinion to be 
rotated and locked in place with respect to its respective worm shaft on 
which it is mounted. The helical idler driven pinion adjustment means 
functions to insure that the two driven helical pinions are equally loaded 
up when their respective worms make contact with the gears on the output 
shaft, in order to get an optimum degree of distribution of loading 
between the two worm shafts. An adjustment feature or load sharing feature 
is provided by having one of the helical idler driven pinions bolted on a 
hub or spider, which is in turn splined to its respective worm shaft. The 
adjustable helical idler driven pinion is bolted to the hub in such a way 
that it is possible to rotate it with respect to the hub through a small 
angle. The rotation of the helical idler pinion relative to the hub is 
accomplished by having slotted or enlarged holes formed through the pinion 
to permit rotation of the pinion relative to the attachment bolts for 
fixedly attaching the idler pinion to the hub after the desired rotation 
adjustment. 
The cone twin drive speed reducer of the present invention is particularly 
adapted for low profile applications, such as applications in the low 
profile mining industry. In one embodiment, the overall height of the 
speed reducer was about eighteen inches, as compared to the prior art 
speed reducers of approximately twenty-four inches in height, which are 
capable of producing the same torque and power. The speed reducer of the 
present invention may be provided with either an air cooling system or a 
water cooling system. 
Other features and advantages of this invention will be apparent from the 
following detailed description, appended claims, and the accompanying 
drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the drawings, and in particular to FIGS. 1 and 2, the 
numeral 10 generally designates a cone twin drive speed reducer made in 
accordance with the principles of the present invention. The speed reducer 
10 includes a suitable housing having a bottom wall 11 on which are 
integrally formed a pair of oppositely disposed mounting base flanges 12 
and 14. The base flanges 12 and 14 are provided with suitable mounting 
bolt holes 13 and 15, for mounting the speed reducer in a desired 
location. 
As shown in FIG. 2, the speed reducer housing includes a front wall 16 
through which is operatively mounted an input shaft 17. As shown in FIGS. 
1 and 3, the speed reducer housing includes a housing left side wall 20 
and a right side wall 21. The numeral 22 designates the housing rear wall. 
The numeral 23 in FIG. 2 designates the housing top wall rear portion, and 
the numeral 24 designates the housing top wall front portion. As shown in 
FIG. 1, the top wall front portion 24 is provided with integral cooling 
fins 25. As shown in FIG. 2, the housing rear wall 22 is provided with 
cooling fins 26. As shown in FIG. 1, the left and right side walls 20 and 
21 are provided on their outer surface with cooling fins 27 and 28. As 
shown in FIG. 1, the housing bottom wall 11 is also provided on its lower 
outer surface with cooling fins 29. 
As shown in FIG. 2, the input shaft 17 is rotatably mounted by a pair of 
suitable roller bearing means, generally indicated by the numeral 32, in a 
journal member 33 that is operatively mounted in an opening 31 formed 
through the front wall 16. The journal member 33 is provided with a 
mounting flange 34 on its outer end, which is secured by suitable machine 
screws 36 and dowels 37 to the front wall 16 and housing top wall front 
portion 24. As shown in FIG. 1, the journal mounting flange 34 is provided 
on its outer surface with a plurality of integral cooling fins 35. As 
shown in FIGS. 1 and 2, the input shaft 17 extends outwardly of the 
journal member 33 and through a suitable retainer plate 40 which 
operatively supports a wiper seal 39 that is mounted around the input 
shaft 17, and which is in operative engagement therewith. The retainer 
plate 40 is secured in place on the outer face of the journal flange 34 by 
suitable machine screws 41. As shown in FIG. 2, an opening 42 is formed 
through the journal flange 34, and it is enclosed by a suitable cover 
plate 43 that is secured in place by suitable machine screws 44 (FIG. 1). 
As shown in FIG. 2, the speed reducer 10 is provided with an air cooling 
system which includes a single cooling fan 47 that is provided with a hub 
48. The hub 48 is operatively mounted by a set screw 49 on the input shaft 
17, in a position spaced outwardly from the retainer cover 40. The fan 47 
is enclosed by a suitable shield or hood 50, which encircles the fan 47. 
The hood 50 has a top portion and integral side portions, but it is open 
at its inner end so as to direct a flow of air over the front, sides and 
top wall portions of the speed reducer housing, and over the 
aforementioned cooling fins 25 through 29. The input shaft 17 extends 
outwardly through an opening 46 formed through a front integral wall 
portion of the fan hood 50. The fan hood 50 is secured on its two sides to 
the left and right walls of the speed reducer housing by suitable machine 
screws 51. The fan hood front wall is provided at each of the lower 
corners therof with a suitable lug 52 which is secured by a suitable 
machine screw 53 to the base flange 14. 
As shown in FIG. 2, the input shaft 17 is provided with an enlarged 
diameter shoulder 54 which abuts the outer side of the cup of the outer 
bearing means 32. The inner side of the cup of the inner bearing means 32 
is seated against a suitable spacer washer 57. A helical idler drive 
pinion or gear 55 is fixed by a suitable key 56 on the inner end of the 
input shaft 17. The idler pinion 55 is retained on the input shaft 17 by a 
suitable lock nut 58. 
As best seen in FIG. 4, the idler drive pinion 55 meshes with and drives a 
pair of laterally spaced apart helical idler driven pinions 61 and 62. The 
idler driven pinions 61 and 62 are operatively mounted on a pair of 
laterally spaced apart worm drive shafts, generally indicated by the 
numerals 59 and 60, respectively. As shown in FIG. 3, the outer end of the 
worm shaft 59 is provided with a splined portion 64 which is operatively 
mounted in a splined bore 63 formed axially through the idler driven 
pinion 61. The worm shaft 59 further includes an enlarged diameter 
shoulder 65 which is adjacent the splined shaft end portion 64, and which 
is rotatably mounted in a suitable roller bearing means, generally 
indicated by the numeral 66. The roller bearing means 66 is operatively 
mounted in a bore 67 which is formed through an internal transverse 
vertical wall 68. The roller bearing means 66 is retained in place in the 
bore 67 by a suitable bearing retainer ring 69 which is secured in place 
by a plurality of suitable machine screws 70. 
The outer end of the worm shaft 59 has a reduced diameter threaded portion 
71, on which is operatively mounted a suitable lock nut 74. The idler 
driven pinion 61 is provided with an integral inwardly extended hub 73, 
which seats against one end of a metal spacer sleeve 72. The inner end of 
the spacer sleeve 72 is seated against the outer side of the bearing cup 
of the bearing means 66. The inner side of the cup of the bearing means 66 
sits against a shoulder formed on the outer side of an enlarged diameter 
portion 76 on the worm shaft 59. A cone drive worm 75 is integrally formed 
on the worm shaft 59, in a position inwardly of the shoulder 76. 
The idler driven pinion 62 is adjustably mounted on the worm shaft 60 by 
the following described structure. As shown in FIGS. 3 and 5, the idler 
driven pinion 62 is adjustably mounted on a hub or spider which is 
generally indicated by the numeral 77. 
The spider 77 is provided with an outer annular shoulder 78 and an integral 
inwardly positioned annular pilot or flange 79. As best seen in FIG. 5, 
the idler driven pinion 62 is provided with a stepped axial bore which 
includes an outer axial bore 80 that terminates at its inner end at a 
larger diameter annular recess 81. The diameter of the annular recess 81 
is made to a close tolerance relative to the outer periphery of the 
annular spider pilot 79 for rotation thereabout for adjustment purposes. 
The axial bore 80 is made to a slightly larger diameter than the outer 
diameter of the spider shoulder 78 to provide a slight clearance. The 
spider pilot 79 is provided with a plurality of evenly spaced, annularly 
disposed threaded holes 85 which are each adapted to communicate with a 
bore or slot 82 in the pinion 62. The bores 82 are of a larger diameter 
than the threaded holes 85. 
The pinion 62 is secured to the spider 77 by a plurality of bolts 83, which 
in the illustrative embodiment, comprise a total of four bolts. As shown 
in FIG. 5, the threaded bodies 84 of the bolts 83 extend through the 
enlarged bores 82 into threaded engagement in the individual threaded 
holes 85 in the spider pilot 79. The bores 82 are made to a size larger 
than the diameter of the threaded end 84 of the bolts 83. For example, if 
a half inch bolt is employed for the bolts 83, then the bores 82 are made 
to a larger diameter, as for example, to a five-eighths inch diameter. It 
will be understood that the bores 82 may also be elongated to form slots 
in an annular direction, so as to permit rotational adjustment of the 
pinion 62 relative to the spider 77. The pinion 62 is set to a desired 
adjusted position as described in detail hereinafter. Briefly, the pinion 
62 is adjusted to the desired position relative to the spider 77, and the 
bolts 83 are tightened. A pair of dowel holes 86 are then drilled and 
reamed through the pinion 62. Simultaneously, a pair of dowel holes 87 are 
formed through the attached pilot 79 of the spider 77. As shown in FIG. 3, 
a suitable dowel pin 93 is operatively mounted in each of the pair of 
aligned dowel holes 86 and 87. It will be seen that the dowel pins 93 
function to carry the rotational torque between the pinion 62 and the 
spider 77, while the bolts 83 apply clamping pressure only to clamp the 
pinion 62 to the spider 77. 
The adjusting of the pinion 62 relative to the spider 77 can be repeated 
after use of the speed reducer to take up any wear, in the manner 
described more fully hereinafter. 
As shown in FIGS. 3 and 5, the outer end of the worm shaft 60 is provided 
with a splined portion 89 which is operatively mounted in a splined bore 
88 formed axially through the spider 77. The worm shaft 60 further 
includes an enlarged diameter shoulder 90 (FIG. 3) which is adjacent the 
splined shaft end portion 89, and which is rotatably mounted in a suitable 
roller bearing means, generally indicated by the numeral 94. The roller 
bearing 94 is operatively mounted in a bore 100, which is formed through 
the internal transverse vertical wall 68. The roller bearing means 94 is 
retained in place in the bore 100 by a suitable bearing retainer ring 97, 
which is secured in place by a plurality of suitable machine screws 98. 
As shown in FIG. 3, the outer end of the worm shaft 60 has a reduced 
diameter threaded portion 92, on which is operatively mounted a suitable 
lock nut 91. The idler driven pinion 62 is provided with an integral, 
inwardly extended hub or shoulder 96, which seats against one end of a 
metal spacer sleeve 95. The inner end of the spacer sleeve 95 is seated 
against the outer side of the bearing cup of the bearing means 94. The 
inner side of the cup of the bearing means 94 sits against a shoulder 
formed on the outer side of an enlarged diameter portion 101 on the worm 
shaft 60. A cone drive worm 99 is integrally formed on the worm shaft 60, 
in a position inwardly of the shoulder 101. 
As shown in FIG. 2, the rear end 102 of the worm shaft 60 is rotatably 
supported by a suitable roller bearing means, generally indicated by the 
numeral 103. The bearing means 103 is operatively supported by a suitable 
bearing retainer member 104 which is operatively mounted in an opening 105 
in the housing rear wall 22. The bearing retainer member 104 is secured in 
position by suitable machine screws 106. 
The lower interior portion of the speed reducer housing forms a reservoir 
for lubricating oil. The numeral 107 in FIG. 2 designates a reservoir 
drain plug. The numeral 108 designates a reservoir fill inlet plug. The 
numeral 118 in FIG. 1 also designates a plug for a reservoir port plug. 
The numeral 119 in FIG. 1 designates a fitting for a reservoir oil level 
indicator. 
The cone drive worms 75 and 99 are meshed with the cone gears 111 and 112, 
respectively. As shown in FIG. 1, the cone gears 111 and 112 are 
integrally formed on the hubs 115 and 116, and they are fixed to the 
output shaft 130 by suitable keys 113 and 114. The inner sides of the gear 
hubs 115 and 116 seat against the shoulders formed by the enlarged 
diameter central shaft portion 117 on the output shaft 130. The ratio 
between the worm 75 and the worm gear 111 is the same as the ratio between 
the worm 99 and the worm gear 112. 
As shown in FIG. 1, the output shaft inner end 120 is rotatably supported 
by a suitable roller bearing means, generally indicated by the numeral 
121. The roller bearing means 121 is operatively supported by a suitable 
bearing retainer plate 122 which is secured in place to the housing side 
wall 20 by suitable machine screws 123. A suitable spacer washer 124 is 
seated between the outer side of the cone gear hub 115 and the adjacent 
inner end of the cup of the bearing means 121. A similar spacer washer 125 
is seated between the outer side of the cone gear 116 and the adjacent 
inner end of the cup of a roller bearing means, generally indicated by the 
numeral 127. The roller bearing means 127 operatively supports the front 
end of the output shaft 130. The bearing means 127 is operatively 
supported by a suitable bearing retainer plate 128 which is mounted in an 
opening 132 in the housing wall 21, and secured to the housing wall 21 by 
a plurality of suitable machine screws 129. The bearing retainer plate 128 
carries a suitable wiper seal 131 which is operatively mounted around the 
shoulder 126 formed on the putput shaft 130. 
FIGS. 7 and 8 illustrate a second embodiment of the invention, and the 
parts of this embodiment which are the same as the parts of the embodiment 
of FIGS. 1 through 6, have been marked with the same reference numerals 
followed by the small letter "a". The embodiment of FIGS. 7 and 8 
illustrate the provision of a modified type of air cooling means, as well 
as a water cooling means. It will be understood that the water cooling 
means could be used separately, as well as in combination with the air 
cooling means. 
As shown in FIG. 8, a fan 133 is mounted on a shaft extension 134 of the 
worm shaft 59a by a suitable set screw 135. A similar fan 133 is also 
mounted on the other worm shaft 60a (not shown). A fan hood or shroud, 
generally indicated by the numeral 136, is mounted around the pair of fans 
133 for directing the flow of air inwardly over the speed reducer housing. 
The shroud 136 may be attached to the housing by any suitable means, as by 
a plurality of attachment straps 138 which are attached to the bearing 
retainer members 104a by suitable machine screws 137. An inlet opening 139 
is formed in the outer end wall of the hood 136. 
A pair of coolant coils 142 and 145 are mounted in the lower end of the 
speed reducer housing for cooling the lubricating fluid in the housing 
reservoir. The coolant coil 142 is provided with an inlet fitting 143 and 
an outlet fitting 144. The coolant coil 145 is provided with an inlet 
fitting 146 and an outlet fitting 147. It will be understood that the 
inlet fittings 143 and 146 would be connected to a suitable source of 
coolant, as for example, a source of cooled water. 
In use, the idler driven pinion 62 would be adjusted to achieve load 
sharing between the gear sets by the following procedure. The output shaft 
130 would be locked in a stationary position by any suitable means. For 
example, a suitable clamp means could be provided to clamp the output end 
of the shaft 130 in a stationary position. The input shaft 17 is then 
turned clockwise to bring the worm threads of worm 75 into contact with 
the gear teeth of gear 111, as shown in FIG. 4 and FIG. 7. That is the 
input shaft 17 is turned until the teeth of idler drive pinion 55 and 
idler driven pinion 61 and the teeth of worm 75 and gear 111 are all in 
simultaneous contact. FIG. 7 and FIG. 9 show in an exaggerated view of 
tooth A on idler drive pinion 55 having a driving face designated as (1) 
and a non-driving face designated as (2). The driving face (1) of tooth A 
is in direct contact with the driven face (1) of driven tooth B on idler 
driven pinion 61. Then the input shaft is clamped in a stationary position 
by any suitable apparatus. 
As shown in FIG. 2 and FIG. 5, with the four bolts 83 released or loose, 
the spider 77 and the right side cone drive worm 99 are turned 
counterclockwise as viewed in FIG. 4 and FIG. 7 to the worm threads 99 are 
moved into contact with gear teeth 112. The idler helical pinion 62 then 
is turned clockwise or in the opposite direction as the rotation of the 
worm 99 to bring the gear teeth of idler driven pinion 62 shown in FIG. 3 
into contact with the idler driving pinion teeth 55. FIG. 7 and FIG. 9 
show in an exaggerated view tooth A on idler drive pinion 55 having a 
driving face designated as (1) and a non-driving face designated as (2). 
The driving face (1) of tooth A' is in direct contact with the driven face 
(1) of driven tooth C on idler driven pinion 62. The idler driven pinion 
62 is held in this preloaded position and tightened to the spider 77 by 
the four bolts 83. The means for holding the input shaft 17 is then 
removed and the lock nut 91 is removed from the right side worm shaft 60. 
Punch pricks or marks are then made on one of the ends of the splines on 
shaft end 89 and its mating space on the helical gear spider 77 for 
location purposes. The adjustable helical gear 62, together with its 
spider 77 which is bolted to gear 62, is then removed as a unit from the 
splined shaft 89. The dowel holes 86 and 87 are then drilled and reamed 
through the pinion 62 and spider 77, respectively. The pair of dowel pins 
93 are then pressed into the pairs of mating drill holes 86 and 87 for 
locking the helical idler drive pinion 62 to the spider 77. Safety wires 
are then used to connect the bolts 83 together. The assembly of the pinion 
62 and the spider 77 is then reinstalled on the right side worm shaft 60 
and the aforedescribed punch marks matched. The lock nut 91 is reinstalled 
and the means for holding the output shaft 130 is removed. The last 
described procedure for adjusting the pinion 62 relative to the spider 77 
may be employed after the speed reducer has been used to take up any 
unequal load distribution that may have developed through a period of use. 
The twin drive cone reducer of the present invention is especially adapted 
for low profile equipment applications, as for example, the requirements 
of low profile equipment for coal mining. The speed reducer 10 is 
constructed and arranged to take advantage of the strength of two 
individually smaller units and combine them into one output, and thereby 
provide a resultant torque and power equal to a speed reducer that 
normally would be higher in profile. The principle of operation of the 
speed reducer 10 includes a single input shaft 17 which is adapted to be 
driven by any suitable electric drive motor. The input shaft 17 drives the 
helical idler drive pinion 55, as shown in FIG. 4. The drive pinion 55 
drives and meshes with the left hand helical idler driven pinion 61 and 
the right hand idler driven pinion 62. The pinions 61 and 62 are 
operatively mounted on the left and right hand worm shafts 59 and 60, 
respectively. The pinions 61 and 62 are at a one-to-one ratio with the 
drive pinion 55. The worm shafts 59 and 60 are provided with worms 75 and 
99, respectively, which mesh with and drive the pair of worm gears 111 and 
112. It will be understood that other ratios may be used between the drive 
pinion 55 and the driven pinions 61 and 62. For example, a ratio of 11/2 
to 1, 2 to 1, and up. It will be understood that the ratio between one 
cone gear set would have to be the same for the other cone gear set. 
It will thus be seen that the overall input torque supplied to the input 
shaft 17 results in a distribution of the torque through the two worms 75 
and 99, and then to the two gears 111 and 112, and then it is recombined 
into one output shaft 130. Experience has shown that one of the 
advantageous features of the speed reducer 10 is that if one gear unit is 
loaded more heavily than the other, there is a tendency for it to wear 
because it is running at a higher load. However, this reduces the load on 
that gear unit, thereby providing a sharing between the two gear units of 
the speed reducer 10. This feature is advantageous because the load 
sharing function tends to improve as the speed reducer is used, whereas 
the prior art devices tend to lose their load sharing ability with 
extensive use. 
While it will be apparent that the preferred embodiments of the invention 
herein disclosed are well calculated to fulfill the objects above stated, 
it will be appreciated that the invention is susceptible to modification, 
variation and change. 
That is, the invention disclosed describes that with the output shaft 
rotation to be in a counterclockwise direction coincident with a clockwise 
direction of the input shaft, tooth contact on the idler drive pinion and 
both idler driven pinions will be simultaneously coincident with drive 
tooth faces marked (1), as shown in FIG. 9. Conversely, with a clockwise 
output shaft direction and a coincident counterclockwise direction of the 
input shaft, tooth contact on the idler drive pinion and both idler driven 
pinions will be simultaneously coincident with drive tooth faces marked 
(2). To reverse the direction of the shaft the process must be redone; 
that is, the spider must be loosened and idler drive pinion 62 moved in 
the reverse direction in order that the teeth on the idler drive pinion 
and both idler driven pinions are in simultaneous contact. This procedure 
insures that the driven tooth faces on both idler driven pinions are in 
simultaneous mesh or contact with the driving tooth faces, or same sides 
of the teeth, on the idler drive pinion, such as shown in FIG. 7 and FIG. 
9. That is, the reverse is true only after the adjustment is made; the 
whole sequence must be reversed to take up the backlash in order to 
equalize load sharing in the other direction.