Ring gear positioner

In a double planetary reduction final drive gearing arrangement for vehicles, a composite ring gear including two ring gear segments, and means for positioning and mounting the ring gear segments in the gearing arrangement, the composite providing a stepped reduction gear ratio and manufacturing economies and advantages.

BACKGROUND OF THE INVENTION 
The present invention relates generally to gear drive mechanisms for 
wheeled vehicles in the nature of heavy duty apparatus used for 
construction, earth working, earth moving and the like. 
More specifically, the invention relates to a double planetary drive 
assembly of large size and capacity for such vehicles, gears therein being 
of such size that a single ring gear, as sometimes heretofore used, can 
cause substantial difficulties in manufacture, primarily in shaping the 
ring gear teeth due to the very long shaper stroke required. Additionally, 
in large single ring gears, heat treating and the holding of required 
tolerances can also cause substantial difficulties. 
Examples of final drive assemblies constituting prior art are shown for 
example in U.S. Pat. No. 3,452,612, entitled WHEEL DRIVE MECHANISM, and 
assigned to a common assignee herewith; and as set forth in my copending 
application for patent entitled WHEEL FINAL DRIVE ASSEMBLY FOR VEHICLES, 
application Ser. No. 879,304, filed Feb. 21, 1978, and also assigned to a 
common assignee herewith. In this patented structure, a single ring gear 
is shown, and the foregoing problems can exist with increases in size. In 
my copending application a composite or two-piece ring gear is broadly 
shown and contemplated, as are mounting means in the gear arrangement or 
system. 
The present invention and application are directed to a composite, two 
component, or two piece, ring gear in a planetary system of the type in 
question. The present application discloses a construction which overcomes 
drawbacks and problems existing in prior known structures, and the 
structure further provides new and improved results as will appear 
hereinafter. 
It is accordingly a primary object of the present invention to eliminate, 
in so far as possible, drawbacks existent in prior known and used 
apparatus, and further to provide a ring gear structure in a planetary 
gearing arrangement or system of a substantial advance in the art, and 
having meritorious improvements both from the standpoint of manufacture 
and operating capabilities and characteristics. 
SUMMARY OF THE INVENTION 
The present invention accordingly is directed to a double planetary final 
drive of large size and capacity for use in heavy duty vehicles, and 
wherein a ring gear incorporated in the double planetary reduction final 
drive arrangement is a multiple component unit, the construction providing 
means to position and combine the two sections or components. 
In a final drive arrangement comprising a double planetary gear reduction 
assembly, a two piece or component ring gear is incorporated, and of a 
structure whereby the composite ring gear provides a stepped reduction 
gear ratio. Means are also provided to secure the two halves or components 
of the ring gear together in a stationary relationship. The fastening and 
securing means include clip or lock means that cooperate with the two ring 
gear components and structure therein, the clips being removably secured 
and accordingly the two pieces of the ring gear are separable and/or 
selectively mountable in the gearing arrangement. 
The present structure, including two relatively narrow ring gears joined 
together to form a composite single entity substantially reduces 
manufacturing problems, and a two ring gear planetary system has 
additional advantages in that different gear pitches can be used on the 
two segments, for example a finer pitch for a lighter loaded inner 
planetary. 
A further advantage of the present invention resides in economies of both 
weight and manufacturing, and the stepped reduction gear ratio, utilizing 
ring gear segments or pieces of different diameters, allows a greater 
range of ratios in a double planetary system.

DETAILED DESCRIPTION OF THE INVENTION 
FIGS. 1 and 2 disclose a type of vehicle with which a double planetary 
final drive assembly of large size and capacity is used. As shown, a 
wheeled front end loader 10 includes an engine compartment assembly 12, a 
bumper 14, an operator's platform 16, a guard rail 18 on platform 16, an 
operator's cab 20, a bucket 22 of a general type operable through 
hydraulic piston and cylinder means generally shown at 24, and an access 
ladder 26 to the operator's platform. The vehicle is equipped with wheel 
and tire units or assemblies 28 and 30. The vehicle is of a structure 
manufactured by the assignee of the present application. 
Wheel loaders manufactured by the assignee company, of a type to which the 
present invention is applicable, are generally discussed herein as a 
background for the present invention, and to show desirability of the 
present structure. The vehicles are of substantial size and weight, and 
the dimensions and specifications play a part in the design of the 
invention, as also manufacture and assembly thereof, while incorporating 
improved operating characteristics. 
FIG. 2 of the drawing discloses in greater detail the wheel assembly, only 
one of which is described herein in detail. The wheel assembly includes 
tire 32 mounted on a split rim 34, the wheel being generally designated 
36. Each of the wheels, four being used in four wheel drive units, or at 
least two in types of vehicles with which the invention is associated, are 
generally separately driven from a power train through a differential, the 
housing of which is indicated at 38, and from which extends a hollow 
differential axle housing 40 terminating in end flanges 42, bolted at 44 
to wheel brake hub 46. 
Axle drive shafts 48, shown in dotted lines, operatively connect the 
differential in the drive train to the wheel drive assembly in a known 
manner. 
The double planetary gear reduction assembly in the final drive arrangement 
is operatively mounted and positioned within the rim portion 34A of the 
split rim 34, and is generally designated 49 in FIG. 2. The gearing 
arrangement is operatively coupled to the drive axles 48 and to the 
individual drive wheels in a known manner, and as shown in greater detail 
for example in my copending patent application above identified, Ser. No. 
879,304. 
The final drive gearing arrangement, as described in greater detail in my 
copending patent application, includes a stationary fixed axle shaft 
support and housing 50 through which the axle shaft 48 extends, and which, 
by virtue of a toothed or splined end 52, is operatively connected into 
the gearing arrangement. The gear train includes a primary sun gear 54 
operatively engaged with the splining at 52, and this primary sun gear in 
turn is operatively engaged with planetary gears 56, which are operatively 
mounted in a usual manner on primary planet gear carrier 58. The planetary 
gears as usual are mounted on stub shafts 60. A clamp or retainer plate 62 
is bolted to the open end of axle housing 50. A bell shaped gear support 
member or ring gear hub 64 is splinedly connected at 66 to the exterior 
end of axle housing 50. 
A composite or two piece ring gear structure in accordance with the 
invention includes a first ring gear piece 68, and a second ring gear 
piece, segment, or component, 70 as shown. The first ring gear piece 68 is 
mounted to its hub 64 by the conventional method of tooth extension in a 
known manner. The hub 64 has teeth 72 machined on the outside diameter 
thereof that mate with internal teeth 74 of ring gear piece 68, and the 
ring gear piece is held in place on the hub by means of locks or locking 
plates 76, bolted at 78 to the hub, and which locks or plates 76 are 
seated in a groove 80. The gear piece or component 68 is assembled on, and 
secured to, hub 64 prior to assembly of the rest of the planetary gear 
system. This manner of mounting of the ring gear piece 68 to its hub is, 
as mentioned, the conventional method of tooth extension, and bolting in 
keeper plates. 
As previously pointed out, a double planetary final drive of large size and 
capacity, with a single ring gear, as shown for example in U.S. Pat. No. 
3,452,612, requires a proportionately very wide ring. This width causes 
difficulties in shaping of the ring gear teeth due to the very long shaper 
stroke required. Heat treating, and holding required tolerances, is also 
very difficult. The present invention obviates or overcomes these 
difficulties by providing a two piece ring gear construction, the two 
pieces being each of more narrow width, and thus overcoming manufacturing 
difficulties. The composite, however, provides the required width for 
operation, and strength, as also improved operating characteristic 
possibilities. 
The second ring gear component or piece 70, generally speaking, is mounted 
on and attached securely to first ring gear piece 68, as will appear more 
specifically hereinafter. This second ring gear component or piece 70 is 
operatively associated with the second planetary system, and interior 
teeth 82 of ring gear piece 70 are operatively engaged with teeth on 
secondary planet gears 84, operatively mounted on stub shafts 86, mounted 
on hub plate cover 90. 
The planetary gears 84 are in operative engagement with secondary sun gear 
92. As pointed out in greater detail in my copending patent application, 
this secondary sun gear is uniquely mounted in the gear train system or 
assembly. To this end the hub plate cover 90 which has a central opening 
therein, is secured by nut, bolt combinations at 94 to an annular portion 
96 of rotatable hub 98. The rotatable hub 98 in turn mounts the split rim 
34 by means of ring 100, with bolts or the like 102, 104. This hub 98 is 
driven through the gearing system by virtue of the secondary planetary 
gearing being mounted to hub plate cover 90. In assembly of the gearing 
system, preliminary to insertion and association of secondary sun gear in 
the gear train, a hollow inner hub part 106 is inserted through the 
central opening, and subsequently inner apertured central web 108 of 
secondary sun gear 92 is positioned, the secondary sun gear being 
supported in operative position by association with the secondary 
planetary gearing members as shown in FIG. 3. An outer hollow hub part 110 
is then inserted and joined to hollow hub part 106 by bolts at 112. The 
hollow hub part 110 is attached to hub plate cover 90 by bolts at 114. A 
spacer plug 115 is insertable through the hollow interiors of the hollow 
hub parts 106 and 110, and is then attached at 116 to the outer hub part 
110. The inner end of the spacer plug 115 operatively contacts the outer 
end of shaft 48, and serves to position it and the primary sun gear 54 
carried thereon, in the gear train. This structure is also described and 
shown in greater detail in my copending patent application. 
The second component or piece 70 of the composite ring gear is mounted to 
and held by ring gear piece 68 through a clipped off extension of the 
internal teeth 82 of ring gear piece 70. This structure is shown in detail 
in FIGS. 4 and 5. The internal teeth 82 have been clipped off in the 
region or area designated 117, adjacent an edge of the ring gear piece, 
with the clipped off teeth of shorter length being designated 118, and 
which are separated from the remainder of the teeth by a groove 120, for 
definition and separate teeth formation. The clipped off teeth 118 engage 
with shallow matching external teeth 122 provided on the exterior of ring 
gear piece 68 adjacent an edge thereof. A plurality of keeper plates 124 
are provided which extend partially into external slots 126 which are 
located on the outer diameter between the inner ends of shallow matching 
teeth 122 and the remainder of ring gear 68. Bolts 128 extend through the 
keeper plates 124 and removably mount and secure them on the end of ring 
gear component 70. These keeper plates removably secure and hold the two 
gear pieces 68 and 70 together, and provide, as an entity, the composite 
ring gear assembly. Bent over tabs 130 on the locking keeper plates 124 
prevent the bolts 128 from loosening. It is to be noted that this method 
and structure of jointing or joining allows the same radial flexing and 
floating as the mounting of the gear segment 68 to its hub 64 permits. 
As an alternative to the foregoing construction it is possible that the 
mounting and holding joint can be made of separate spline teeth, which may 
be desirable when the internal ring gear teeth 82 of gear segment 70 are 
of very coarse pitch. Such a structure is within the scope and teachings 
of the present invention, and can be readily provided. The number of 
keeper plates or locks can vary as necessary or desired. It is 
contemplated, for example, that in structures presently in use there may 
be four or six of these locks, although more or less can be used. 
The composite or two piece ring gear as shown and described has additional 
advantages. Different gear pitches can be used, a finer pitch being used 
for the lighter loaded inner planetary as an example. This can provide 
economies both of weight and manufacturing costs. The stepped ring gear 
diameters also allow greater ranges of ratios of the double planetary. 
While a preferred embodiment of the invention has been shown and described, 
manifestly minor changes can be effected in details of structure, without 
departing from the spirit and the scope of the invention, as defined in, 
and limited solely by the appended claims.