Power transmitting device for an oil well pump

A power transmitting device for an oil well pump of the type which utilizes a rotating power source and provides an input capable of operating a pair of cranks for driving a reciprocating pump. The power transmitting device includes a first speed reducer having an input shaft with a pinion bevel gear mounted thereon with the input shaft being operably connected to the power source. The first speed reducer also includes a ring bevel gear in meshing engagement with the pinion bevel gear which is fixedly mounted on a intermediate location of a rotatable output shaft. The output shaft operates a second speed reducer at each end thereon which is capable of providing an output which can be directly coupled to the cranks. The invention includes a method of manufacturing utilizing a number of existing components.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a power transmitting' device for use in an oil 
well pump and, more specifically, to such a device which provides speed 
reduction from a single input shaft which is driven by a rotating power 
source to two output shafts which are capable of driving a crank means to 
provide the power to a reciprocating pumping device of the oil well pump 
and to a method for making the same. 
2. Description of the Prior Art 
It is common in the oil industry to utilize reciprocating oil well pumps of 
the type which are powered by a rotating power source. Typically, the 
power source is an electric motor although diesel driven engines or the 
like could also be utilized. Because electric motors and engines operate 
more efficiently at higher speeds and the reciprocating motion of the pump 
is at a significantly lower speed, some speed reduction is required in the 
transmission of power from the power source to the reciprocating pump. 
Although some reduction in speed can be produced at the output of the 
motor through a belt and pulley or chain drive means, it has been found 
preferable to include a power transmitting device which includes 
significant speed reduction between the power source and the pump. 
U.S. Pat. Nos. 1,972,660; 1,979,803; 3,183,728; 3,427,887; 3,621,723; 
3,706,234; 3,867,846 and 4,051,736 disclose oil well pumps of the type 
mentioned above and, because of the forces required to operate the pumps, 
teach that it is advantageous to utilize a dual pitman or connecting rod 
configuration for balanced loading on the power transmitting device and 
other pump components. Each includes dual output shaft means from a power 
transmitting, speed reducing device which drive some type of crank arms 
for the operation of the pitmen. It is common to include counterweights on 
the crank arms for even loading during operation of the pump. However, the 
walking beam configurations to which the pitmen are connected are of 
various designs as are the means employed for coupling the power source to 
the input of the speed reducer. 
Although the speed reducers utilized in the oil well pumps disclosed in the 
patents mentioned hereinabove might differ, they each appear to utilize a 
single input shaft which drives a series of spur, helical or herringbone 
gears to transmit the power to the output shaft. The output shaft is 
parallel to the input shaft and has crank means mounted at each end 
thereof. While these types of power transmitting, speed reducers appear to 
be most common in recent oil well pump installations, there has heretofore 
been utilized other gear means for transmitting power from and reducing 
the speed of the power source. U.S. Pat. Nos. 1,821,216; 1,858,185; 
1,915,827; 2,161,298; 2,197,730; 3,208,291 and 3,221,569 include speed 
reducers having input shafts which are not parallel to the output shafts. 
A number of these speed reducers can be seen to include worm gear drives 
although the detailed operation of others is not fully disclosed. In any 
case, they each disclose that the output shaft is directly coupled to a 
single or dual crank means for the operation of the reciprocating pump. 
While any number of these devices might have been and continue to be 
successfully utilized in the oil pumping field, there remains a need to 
provide a power transmitting speed, reducing device which is reliable and 
inexpensive to provide. Obviously, any power transmitting speed, reducing 
device, which might be more efficient than the spur, helical, herringbone 
or worm gear devices used heretofore, would be desirable to reduce the 
design requirements and operating costs for the power source. 
Additionally, any such installation should include means for effectively 
maintaining or repairing the power transmitting, speed reducer device as 
quickly and conveniently as possible so there would be less interference 
with the operation of the oil well pump. 
SUMMARY OF THE INVENTION 
It is, therefore, an object of this invention to provide a power 
transmitting device for an oil well pump which is reliable and efficient 
and is capable of being easily maintained. 
It is a further object of this invention to provide such a power 
transmitting device which can be inexpensively manufactures. 
It is another object of this invention to be able to manufacture such a 
device as much as possible with existing components which have been 
extensively utilized under similar operating conditions and have a proven 
reliability. 
These and other objects of the invention are provided in a preferred 
embodiment thereof including a power transmitting device for an oil well 
pump of the type which utilizes a rotating power source and provides an 
output capable of operating crank means for driving a reciprocating pump 
means. The power transmitting device includes a first speed reducing means 
including an input shaft means having pinion bevel gear means mounted 
thereon with the input shaft means being operably connected to the power 
source. The first speed reducing means includes a ring bevel gear means in 
meshing engagement with the pinion bevel gear means and being fixedly 
mounted at an intermediate location on a rotatable output shaft means. 
There is included means for coupling each of the opposite ends of the 
output shaft means to the crank means. The invention can also include the 
provision of a second speed reducing means at the opposite ends of the 
output shaft means which includes an output hub to which the crank means 
can be directly coupled. The invention also includes a method of 
manufacturing the power transmitting device including the utilization of 
existing components.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
As seen in FIGS. 1 and 2, a typical oil well pump 10 is mounted on a base 
12 which can be made of concrete or other permanent structure or can be 
made of steel to allow the pump 10 to be capable of being moved to 
different sites. A samsom frame 14 extends upwardly from the base 12 and 
includes a saddle bearing 16 at the upper end thereof. The saddle bearing 
16 pivotally supports a walking beam 18 which has a mule head 20 mounted 
on its forward end. A bridle cable 22 is connected to the upper end of an 
oil well pump rod (not shown) in a manner well known in the oil industry. 
To impart reciprocal motion to the walking beam 18, a pair of pitmen or 
connecting rods 24 are joined at their upper ends through an equalizing 
connector 26 which is secured to the rear end of the walking beam 18. The 
lower end of each pitman 24 is pivotally joined to a crank arm 28 having a 
suitable counterweight 30. Each crank arm 28 is mounted for rotation at an 
end 32 to one of the outputs of a power transmitting device 34 supported 
by a frame 35. 
This invention is directed to the power transmitting device 34 which is 
shown in FIGS. 3, 4 and 5 and will be discussed in detail hereinbelow. 
However, it is sufficient for a general understanding of the oil well pump 
10 to know that a rotating power source 36 can be coupled through a pulley 
and belt or chain drive means 38 to a single input shaft of the power 
transmitting device 34. The power source 36, as shown in FIGS. 1 and 2, 
includes an electric motor, although a diesel or gas engine might be 
utilized in some installations. The electric motor has an output pulley 
mounted on the output end thereof. In the embodiment shown in FIGS. 1 and 
2, the pulley drives a belt means which is received around and drives a 
pulley directly coupled to the input shaft of the power transmitting 
device 34. It should be clear to those skilled in the art that some speed 
reduction can be obtained by the proper selection of the pulleys for the 
motor and the input shaft to the power transmitting device 34 but there 
are practical limitations including belt wear or life and the ability to 
transmit the power without slippage if there is too great a difference in 
the diameters of the pulleys. 
As thus described, most of the features of the oil well pump 10 are typical 
of those found in a number of installations presently being employed in 
the oil industry. However, one would normally expect to see the power 
source 36 oriented with its axle in general alignment with the axis of 
rotation of the crank arms 28 since the pulley and belt drive usually 
provide power to an input shaft which is parallel to the output shaft of a 
different type of power transmitting, speed reducing device than the 
device 34. As mentioned hereinabove, such a previously employed power 
transmitting, speed reducing device would likely include spur, helical or 
herringbone gears mounted on shafts with their axes in parallel to provide 
for the desired transmission of power and reduction of speed. However, the 
orientation of the power source 36, as shown in FIGS. 1 and 2, would be 
consistent with the utilization of a worm gear configuration as also 
disclosed in some of the patents mentioned hereinabove. 
In either case, as thus far described, the oil well pump 10 does not 
include any features, with the exception of the power transmitting device 
34, which are not generally known in the oil industry. It should be kept 
in mind that the oil well pump 10 is merely representative of any number 
of equally suitable configurations which can be utilized to employ the 
rotating motion of a crank arm to produce the reciprocating action needed 
to operate an oil well pump. Consequently, it will be seen that any number 
of configurations shown in the patents mentioned hereinabove could be 
readily adapted to utilize the power transmitting device 34 as a means for 
taking power from a single rotating power source and converting it to a 
slower rotating pair of output means which can provide power to a pair of 
crank arms. 
As seen in FIGS. 3, 4 and 5, the preferred power transmitting device 34 
includes an input shaft 40 which drives a first speed reducing means 42. 
The first speed reducing means 42 is directly coupled to a pair of output 
shafts 44 extending outwardly at each side thereof. Each output shaft 44 
is coupled at its outer end to a second speed reducing means 46. Each 
second speed reducing means includes a hub or output fitting 48 which can 
be directly coupled to a crank arm to produce the rotary motion which can 
then be converted to reciprocal motion in a manner described hereinabove. 
In other words, speed reduction provided by the preferred power 
transmitting device 34 is accomplished in two stages. The first speed 
reducing means 42 is centrally located in the power transmitting device 34 
and converts rotating torsional power from the input shaft 40 to the 
output shafts 44 which are not aligned with the input shaft 40. The output 
shafts 44 then supply torsional power to the second speed reducing means 
located at their outer ends to impart rotation to the crank arms about a 
common axis of rotation but at a significantly slower rotational speed 
than that produced by the power source. 
To properly support and provide lubrication for the first speed reducing 
means 42, the second speed reducing means 46 and other elements associated 
with the power transmitting device 34, the rotating elements are housed 
within a sealed container which includes a sufficient lubricating oil for 
splash lubrication or other lubricating means well known in the power 
transmitting field. Specifically, the first speed reducing means 42 is 
supported by and mounted within a housing 50. Output shaft housing 52 is 
mounted to extend to each side of the housing 50 to receive the output 
shafts 44 therein. The housing 50 and the shaft housing 52 combine to 
provide integrity for the power transmitting device 32. Additionally, the 
housings 50 and 52 include bearings for the support of the rotating 
members found in the power transmitting device 34 and sufficient fixed and 
running oil seal means to retain lubricant oil for the operation of both 
the first speed reducing means 42 and the second speed reducing means 46. 
The input to the power transmitting device 34 includes a pulley 54 which is 
driven by the power source and secured to an outward end 56 of the input 
shaft 40. The input shaft 40 is mounted for rotation at bearings 58 which 
are secured to and supported by the housing 50. A brake 60 is also mounted 
about the outer end 56 of the shaft 40 and provides a selectively operated 
means to insure against rotation of the power transmitting device 34 
during initial assembly or maintenance of the oil well pump. 
The inward end of the input shaft 40 includes a pinion bevel gear means 62 
which is in driving engagement with a ring bevel gear means 64 of the 
first speed reducing means 42. In the preferred embodiment, the first 
speed reducing means is not, in fact, technically a true bevel gear 
configuration in that the axis of rotation of the shaft 40 does not 
intersect the axis of rotation of the ring gear 64. Although it would be 
possible to utilize such a bevel gear arrangement to provide both for 
speed reduction and to convert the input rotation to rotation about a 
differently oriented axis, the preferred pinion gear 62 and ring gear 64, 
specifically shown in FIGS. 3 and 4, are of a hypoid-type which requires 
the input shaft 40 to be aligned above the axis of the ring gear 64 thus 
preventing any intersection of their axes. More technically, this could be 
described as a skew bevel gear arrangement with the hypoid-type of gears 
having a particular tooth design which has been commonly utilized in and 
accepted by the automotive industry for speed reduction and the 
transmission of power from one input shaft to two output shafts. As will 
be made clear hereinbelow, the hypoid-type pinion and ring gear 
configuration is considered the preferred because of its efficiency and 
the fact that it has been proven to be highly reliable and satisfactory in 
the automotive industry. Therefore, although the hypoid-type is the 
preferred, any number of bevel gear configurations might be utilized and, 
in fact, such a spiral bevel gear means has been satisfactorily employed 
in one embodiment. 
The ring gear 64 is formed on a casing 66 which is supported for rotation 
within the housing 50 at bearings 68. The casing 66 preferably includes a 
spider 70 having four outwardly extending posts rigidly retained thereby. 
The spider 70 has a splined central bore 72 which receives the splined 
inward ends 74 of each shaft 44. While this configuration is the 
preferred, it should be clear that any means for rigidly securing the ring 
gear to the inward ends of the shafts 44 would be acceptable. In fact, 
there is no requirement that the shafts 44 be independent, although this 
is desirable in the preferred embodiment for a number of reasons which 
will be discussed in detail hereinbelow. The ring gear 64 could be 
directly mounted at an intermediate location on a single shaft with its 
opposite ends extending outwardly of the ring gear 64. 
As thus described, the first speed reducing means 42 in one embodiment 
which has been satisfactorily employed in an oil well pump provides a 
speed reduction of 7.8 to 1. Although a greater amount of reduction may be 
obtained from a bevel gear configuration, a skewed bevel gear 
configuration or a hypoid-type gear configuration, the amount of reduction 
selected in the preferred embodiment is sufficient because of the 
existence of the second speed reducing means 46. However, as mentioned 
heretofore, if the power source were to be operated at a slower speed or 
if the pulley and belt configuration were to be so selected, it might be 
possible for the first speed reducing means to be utilized exclusively for 
reducing the speed in a power transmitting device. In other words, the 
shafts 44 could be employed to be directly coupled to a crank arm 
configuration for the operation of the oil well pump. 
However, in order to allow a higher operating speed for the power source, 
the preferred power transmitting device 34 employs the second speed 
reducing means 46 to further reduce the speed of the output shafts 44 and 
provide the hub 48 which can be directly coupled to the crank arm. The 
second preferred speed reducing means 46 is a planetary gear reducer. 
Specifically, the output shaft 44 has at its outer end a sun gear 76 of 
the second speed reducing means 46 rigidly mounted thereon. The second 
speed reducing means 46 also includes a ring gear 78 which is rigidly 
secured to the shaft housing 52 to prevent its rotation. Planetary gear 
means 80 is provided between the rotating sun gear 76 and fixed ring gear 
78 to respond to rotation of the sun gear 76 by the output shaft 44. In 
the preferred embodiment, the planetary gear means 80 includes three 
planetary gears 82 which are evenly spaced circumferentially about the sun 
gear 76 and are mounted to and supported by an end plate and spider 84 of 
the hub 48. The hub 48 is mounted for rotation at bearings 86 which are 
mounted on the shaft housing 52. As thus explained, the hub 48 is 
supported by and capable of rotating relative to the shaft housing 52 and 
is driven by the planetary gears 82 secured thereto. Consequently, the sun 
gear 76 is retained inwardly of each of the planetary gears 82 which are, 
in turn, retained in their location by their being mounted within the ring 
gear 78. 
As thus described, the preferred second speed reducing means 46 provides a 
speed reduction of 3.6 to 1. Therefore, the power transmitting device 
utilizes both the first speed reducing means 42 and the second speed 
reducing means 46 and provides an overall speed reduction of about 28 to 
1. One embodiment of the preferred power transmitting device 34 has an 
efficiency of 94% which compares favorably with any of the prior art 
devices mentioned hereinabove. It should be kept in mind that although the 
preferred second speed reducing means 46 is a planetary gear reducer, it 
might be possible to employ other types of reduction gears at the ends of 
the output shafts 44 without unduly reducing the overall efficiency. 
While explaining the preferred power transmitting device 34, it should be 
clear to those skilled in the art that various features could be modified 
while still satisfying the broad objective of the invention and without 
departing from the spirit of the invention as claimed. However, there are 
a number of features incorporated in the preferred power transmitting 
device 34 to satisfy of a number of other objectives of this invention. As 
mentioned hereinabove, any power transmitting, speed reducing device to be 
used in an oil well pump should be efficient, reliable and relatively 
inexpensive to provide. Although with the ever increasing demand for oil 
products, there has been and will continue to be a large demand for oil 
well pumps, the scale of production of a power transmitting device which 
can only be used in the oil industry would significantly add to the cost 
of such a device. In other words, while the potential market for such a 
power transmitting device in the oil industry might require sufficient 
production quantities to justify a unique design which requires capital 
inventment in heavy equipment industry, machinery and tooling, it would, 
obviously, be desirable to have a design which utilized existing 
components as much as possible. 
The utilization of components from an existing vehicle drive system used in 
the automotive industry would, obviously, be advantageous. Components 
extensively found and successfully employed in such a large, established 
industry would possess proven reliability and insure a valuable source of 
supply parts should they be necessary. From a production viewpoint, if 
parts or whole components presently being utilized in a vehicle drive 
system could be directly employed in a preferred power transmitting device 
34, there would be no need for initial capital expenditure in special 
equipment or tooling as might be required for a totally unique design. 
Therefore, while there is a significant demand for a new power 
transmitting device in the oil industry, if could in no way compare to the 
number of vehicle drive systems which are presently in production. The 
economic impact of providing various components for such a power 
transmitting device in the oil industry would be significantly reduced by 
the utilization of such components from the automotive industry. 
Furthermore, a number of characteristics found in the vehicle drive 
systems which have been incorporated to gain acceptance in and meet the 
approval of the automotive industry are also attractive for this type of 
application in the oil industry. 
As seen in FIG. 6, an existing, rather typical vehicle drive system 100 
includes a drive axle housing 102 with a centrally located differential 
104 of a type which is well known in the art. An input drive shaft 106 is 
capable of being coupled at its outer end 108 to a vehicle drive shaft 
from the transmission, transfer case, or other power transmitting device 
in the vehicle (not shown). The input shaft 106 can include a parking 
brake 110 mounted on the housing 104 to be selectively operated to prevent 
rotation of the shaft 106. A pinion gear 112 of the hypoid-type is 
utilized to drive a hypoid-type ring gear 114 of a differential casing 
116. A spider 118 is secured within the differential casing 116 and 
includes four differentially pinion gears 120 mounted for rotation 
thereon. The pinion gears 120 are in meshing engagement with a pair of 
side gears 122. Each side gear 122 includes a splined central bore 126 and 
is received upon the splined end 128 of a drive axle 124. 
As mentioned hereinabove, the preferred hypoid-type pinion and ring gears, 
which are commonly found in such differentials and have been 
satisfactorily and extensively employed in the automotive industry to 
efficiently transmit power from a single input shaft to a pair of output 
axles, inherently provides the desired speed reduction. These types of 
gears are considered to be more efficient than the helical, spur, 
herringbone or worm gear configurations mentioned hereinabove. While this 
pinion and ring gear configuration, as suggested above, might provide 
satisfactory speed reduction for some applications, there are other 
applications in the automotive industry requiring further speed reduction. 
Some heavy duty off-highway vehicles and other vehicles, such as fork lift 
trucks, are generally operated at a lower speed than the conventional 
automobile or heavy duty on-highway vehicles. For such a low speed 
operation, it is desirable to have a further reduction of speed at the 
wheel end of the vehicle. 
Accordingly, the existing vehicle drive system 100 also includes a 
planetary gear reducer 130 at the outward end of each drive axle 124. 
Specifically, the planetary gear reducer 130 would include a sun gear 132 
rigidly secured to the end of the drive axle 124 with a ring gear 134 
rigidly mounted to the axle housing 102. A planetary drive means 136 is 
secured to an end plate and spider 138 of a hub 140 to transmit the 
rotating power of the drive axle 124 the hub 140 causing it to rotate. The 
hub 140 is mounted at bearings 142 on the axle housing 102 for its 
rotation and support independent of the drive axle 124 and would have 
wheels and tires (not shown) mounted thereon to support and power the 
vehicle. Many different types of brakes 143 and suspensions 145 can be 
utilized to complete the drive axle system 100 as it would typically be 
seen on a vehicle. 
As thus described, it can be seen that the vehicle drive system 100 might 
appear to be capable of being directly utilized as a power transmitting 
device for an oil well pump. However, the differential action resulting 
from the inclusion of a differential would be undesirable because it is 
essential for the crank arms of an oil well pump to move simultaneously 
and to be as evenly loaded as possible. 
Although the typical vehicle drive system includes a differential 
mechanism, it should be kept in mind that there are occasions in the 
operation of a vehicle when differentiation is not desired. In the 
automotive field it is well recognized that spin out or excessive slipage 
of one of the vehicle wheels is unattractive since the spinning wheel can 
prevent power from being applied to the other wheel which might have 
traction and be capable of moving the vehicle. Therefore, it is quite 
common for vehicle drive systems similar to system 100, to include a means 
for selectively preventing the relative rotation of the drive axles 124. 
One such means includes a device for applying a braking force to the end 
of the differential casing to prevent it from rotating relative to one of 
the drive axles 124 and thus cause both drive axles 124 and the 
differential casing 116 to rotate together. There are many other means 
employed in and accepted by the automotive industry for accomplishing this 
objective. Since there are selective means for preventing the relative 
rotation of the drive axles 124, it should be clear that some means can be 
employed to modify or alter a differential to prevent the relative 
rotation of the drive axles 124 throughout operation of the vehicle drive 
system. 
With this possibility in mind, it can be seen that specific limited 
modification of a vehicle drive system of the automotive industry would 
enable it to be employed to provide a power transmitting means for an oil 
well pump. However, many such vehicle drive systems would be considered 
too long to be directly installed in existing oil well pump 
configurations. One practical limitation on existing pumps is the distance 
between the pitmen and, therefore, the length of the equalizing connector. 
The length is determined by the desire to be able to transport oil well 
pumps of this type. In other words, an oil well pump, such as the type 
shown in FIGS. 1 and 2, is often designed to be mounted on a large 
transport truck to be capable of being taken from one oil well site to 
another. Transporting in this manner requires the use of public highways 
and thus limits the overall width of such an oil well pump configuration. 
However, if the oil well pump is intended to be permanently installed on 
one site or is to be utilized at multiple sites in a large field without 
use of the public highways, it might be possible for any number of vehicle 
drive systems to be directly employed if the differentials are modified to 
prevent the relative rotation of the drive axles. In fact, some fork lift 
trucks have a short wheel base and include vehicle drive systems with an 
overall length consistent with this practical limitation for oil well 
pumps. 
Although it would be possible in some installations to directly employ an 
existing vehicle drive system with minimum modifications, the existing 
vehicle drive system does include some elements which can be eliminated 
and are eliminated in the preferred embodiment. Obviously, if a specific 
component can be designed to be better employed in an oil well pump 
configuration while reducing the overall cost of the power transmitting 
device, such a design would be attractive. Accordingly, rather than having 
a spider 118 having differential pinions 120 mounted thereon, the 
preferred embodiment utilizes a spider 70 which eliminates the 
differential pinion gears 120. Additionally, since the output shafts are 
not to be driven through a differential, there would be no need for side 
gears 122. As a result, the prefered power transmitting device 34 utilizes 
the spider 70 and includes a means for directly coupling the shafts 44 
thereto. 
Similarly, since, as mentioned hereinabove, the overall length in this 
application is less than the overall length of the vehicle drive system 
100, the existing drive axles 124 are not utilized but a specifically 
shorter drive shaft 44 has been selected. Because of the reduction in the 
length of the drive shaft 44 versus the length of the drive axle 124, the 
outwardly extending portions of the axle housing 102 which support the hub 
140 would be too long so that a shorter shaft housing 52 has been 
employed. 
It can, therefore, be seen that the preferred power transmitting device 34 
can be manufactured by using many existing components from the vehicle 
drive system 100. Specifically, the pinion gear 62 is identical to the 
pinion gear 112. The ring gear 64 is identical to the ring gear 114. 
Similarly, the casing 66 is identical to the differential casing 116. All 
of the components at the end of the shaft 44 are identical to those found 
in the vehicle drive system 100 so that the second speed reducing means 46 
and hub 48 are identical to the planetary gear reducer 130 and wheel hub 
140. Even the parking brake 110 can be directly utilized to provide the 
brake 60. Additionally, any number of bearings and seals which are found 
in the vehicle drive system 100 can be and are directly utilized in the 
preferred power transmitting device 34. 
As explained hereinabove, the preferred power transmitting device 32 can be 
efficiently and reliably employed in an oil well pump. However, there are 
also additional characteristics which make it particularly attractive and 
unique as a power transmitting device for this purpose. As mentioned 
above, the crank arms 28 can be directly coupled to the hubs 48. As seen 
in FIGS. 1 and 2, the crank arm 28 is mounted to the hub 48 at a large 
hole 150 therein which does not overlie or interfere with the end plate 
and spider 84 of the hub 48. As a result, any repair to the planetary 
reduction gears of the second speed reducing means 46 can be accomplished 
without uncoupling the crank arm 28 from the hub 48 or requiring its 
removal. A review of the prior art devices shown in the patents mentioned 
hereinabove, reveals that the crank arms are usually directly mounted to 
the output shafts. Consequently, any work to be done to the power 
transmitting devices in these prior art installations would require the 
removal of the crank arm and, therefore, significantly complicate 
maintenance or repair. In fact, power transmitting device 34 includes the 
same repair and maintenance capabilities as the vehicle drive system 100 
which is commonly employed and recognized as essential in the automotive 
industry. Any failure of rotating components in the vehicle drive system 
100 can be corrected without requiring the removal of the hubs 140. In 
fact, all of the internal components can be removed by extraction at the 
outer ends of the drive axle housing 102 or the differential cover. As a 
result, any failure of the rotating components within the power 
transmitting device 34 can be corrected without significant down time for 
the oil well pump. In fact, the input shaft 40, the ring gear 64, the 
shafts 44 and the operating gears of the planetary gear reducer could all 
be completely replaced in the field in about two hours. Should such 
repairs be necessary, it should be kept in mind that the utilization of 
many components which are currently being used in the automotive industry 
insures that satisfactory and reliable spare parts can be obtained. The 
availability of these components as spare parts in the automotive industry 
insures their availability for the oil industry. 
There is yet another advantage of looking to the automotive industry for a 
solution to the power transmitting problems in the oil industry. In the 
present explanation, it may have seemed that one particular form of the 
preferred embodiment could be utilized to satisfy oil well pump 
requirements. However, when providing a power transmitting device 32, an 
analysis of the forces required in the oil well pump and the speed 
reduction required for a given power source is taken into consideration. 
These requirements, as a practical matter, are different for different oil 
wells. Therefore, in the oil industry, there are usually provided a wide 
range of oil well pump configurations from which a selection is made to 
satisfy the particular job required. However, in the automotive industry 
there is also a wide range of vehicle drive requirements. It has been 
found that with the simple modifications mentioned above, a wide range of 
requirements for the oil well pump can be satisfied from the wide range of 
existing vehicle drive system configurations. Therefore, not only does the 
utilization of components from the automotive industry reduce the 
production and repair costs which would otherwise be required for a power 
transmitting device in the oil industry, but it also includes a wide range 
of such products so that a similar wide range of power transmitting 
devices can be properly employed in the oil industry. 
As thus explained, the preferred power transmitting device 34 can be 
readily and inexpensively provided for utilization in an oil well pump. 
The particular configuration of one speed reduction means with additional 
speed reduction means mounted at the ends thereof provides power 
transmission which is more efficient than many of the systems presently 
employed. Additionally, this configuration includes means for facilitating 
maintenance and the replacement of spare parts should they be required. 
While the embodiment presented hereinabove is the preferred embodiment, it 
has been made clear that a number of alterations could be made without 
departing from the spirit of the invention as claimed.