Ground wheel takeoff system for fertilizer spreaders or the like

There is disclosed a ground wheel takeoff drive system for fertilizer spreaders or the like including a gearbox being adapted to reside at least partly inside one of the speader's pneumatic tire and wheel cavities and having a hollow shaft journalled therein through which passes the axle on which the tire and wheel is mounted. The hollow shaft is secured to rotate with the ground wheel and a restraining element causes the gearbox to be restrained from rotation. The gearbox has a sprocket which is geared to be driven from the rotating hollow shaft, a remote control cable arrangement is connected to a gear lever on the gearbox which slides a driven gear in and out of engagement with a gear secured to the hollow shaft so that the gearbox sprocket motion may be disabled or enabled from a remote position; a sprocket chain is provided with suitable idlers for driving a sprocket wheel connected in a conventional manner to the gear drive mechanism for the fertilizer spreader.

The present invention relates to ground wheel takeoff drive systems used in 
unpowered wheeled vehicles to impart motion from the rotating ground wheel 
to conveyors, fans, paddles or other mechanisms on the vehicle. 
A common method of imparting motion to mechanisms on fertilizer spreaders 
or other such vehicles is to provide a driven wheel in frictional 
engagement with the rubber tire of the ground wheel. Such systems are 
quite workable in optimum conditions, but when the vehicle is used in wet 
fields or other adverse conditions the frictional engagement with the tire 
becomes unreliable and significant slippage can cause the driven mechanism 
to run at slower than the desired rate of speed. This results in 
inaccurate application of fertilizer or other improper functions of the 
apparatus. 
Typically, fertilizer spreaders do not have a rotating axle which can be 
utilized as a takeoff drive element but rather the vehicle wheels are 
freely rotating on a spindle secured to a nonrotating axle on a rocker 
suspension or other type of suspension. Thus some prior takeoff mechanisms 
which utilize a rotating axle would be unsuitable for adaptation to a 
ground wheel takeoff drive system for fertilizer spreaders or the like. 
Ground wheel takeoff drive systems for fertilizer spreaders or the like 
which rely on frictional engagement with a rubber tire are exemplified by 
U.S. Pat. No. 4,283,014 to Devorak (Granted Aug. 11, 1981). A hydraulic 
takeoff drive arrangement is disclosed in U.S. Pat. No. 3,019,025 to G. V. 
Young (Granted Jan. 30, 1962). 
The present invention overcomes the disadvantages of prior apparatus by 
utilizing a direct drive through a gearbox having a hollow shaft 
journalled therein which hollow shaft fits over the axle or spindle for a 
ground wheel. The hollow shaft has a flange which connects to the ground 
wheel hub causing the shaft to rotate therewith while the gearbox is held 
stationary by engagement with a stationary part of the vehicle. The 
internal gearing in the gearbox is arranged to be placed in an engaged or 
neutral position, and when in the engaged position a sprocket on the 
gearbox is rotated to drive a chain belt and a frame mounted sprocket and 
gear mechanism for a conveyor, impeller fans, etc. In this manner positive 
drive rather than frictional engagement is relied upon yet the mechanism 
involved is quite compact and resides for the most part in the central 
open space surrounded by the vehicle tire and rim. 
The chain drive is provided with an idler and thus movement of the axle to 
which the gearbox is mounted is readily compensated by the sprocket chain 
idler mechanism. The gearbox is preferably sealed and oil filled so that 
friction is minimized and little maintenance is required while the 
apparatus is still rugged and durable in adverse field conditions. 
Replacement of the sprocket chain when necessary is readily accomplished 
due to ready accessibility of the sprocket chain. 
In addition to providing the above features and advantages it is an object 
of the present invention to provide a ground wheel takeoff drive system 
for unpowered wheeled vehicles including a gearbox with a hollow system 
adapted to encircle the ground wheel axle and be secured to rotate with 
the ground wheel. 
It is another object of the present invention to provide a positive gear 
drive ground wheel takeoff arrangement for fertilizer spreaders or the 
like wherein the gearbox connected for imparting rotation for the wheel to 
a sprocket chain is secured generally within the outline of the ground 
wheel tire and rim. 
It is still another object of the present invention to provide a ground 
wheel takeoff drive system for fertilizer spreaders or the like with a 
gearbox secured within the ground wheel and rim and having a gear 
engagement lever connected through a remote operating system to permit the 
gearbox to be engaged and disengaged remotedly.

Referring now to drawings and particularly FIGS. 1 and 2, a fertilizer 
spreader is shown which is of generally conventional construction having 
impeller fans or paddles 11 for distributing the fertilizer and a conveyor 
12 for feeding fertilizer to the fans 11. A conventional gear mechanism 13 
is provided for driving conveyor 12 and fans 11. 
A sprocket and shaft 29 serves as the input to power the gear mechanism 13 
and sprocket 29 is engaged by chain belt 31 which is driven by sprocket 41 
on gearbox 21 of the ground wheel takeoff system. 
Because the ground wheel is mounted on a resilient suspension the distance 
between sprocket 41 and sprocket 29 may vary by several inches and an 
idler mechanism with two sprockets 25 and 26, an arm 23 pivoted at pin 24 
and a spring 27 for urging the arm upward keeps the slack out of chain 
belt 31 and maintains proper tension therein. 
Wheel 15 is mounted on an axle 50 which is nonrotating and is rigidly 
secured to suspension arm 52 of conventional construction, as seen in 
FIGS. 2 and 3. 
Axle 50 for wheel 15 passes through a hollow shaft 51 which is journalled 
in bearings 65 and 67 in gearbox 21. A flange 53 is provided on shaft 51 
which bears against a spacer ring 61 which in turn bears against the hub 
of wheel 15. By selecting a spacer 61 of appropriate width the position of 
gearbox 21 may be determined so that interferences with any part of wheel 
15 is avoided. Flange 53 and spacer ring 61 may be secured to wheel 15 by 
placing bolts 60 through existing holes or holes specially provided in 
wheel 15; nuts 59 engage bolts 60 to hold shaft 51 and flange 53 securely 
in place concentric with wheel 15. This also positions gearbox 21 which is 
thereby constrained to only rotational movement relative to shaft 51. In 
the illustrated embodiment a bar 62 is welded or otherwise secured to 
suspension arm 52 in a vertical position immediately adjacent gearbox 21 
thereby preventing rotational movement of gearbox 21 relative to 
suspension 52. 
Referring now to FIGS. 4 to 6, main gear 63 of gearbox 21 is keyed to 
hollow shaft 51 to rotate therewith and thus rotates within the housing of 
gearbox 21. 
The shaft 43 is mounted in bearings 71 and 73 and extends through bearing 
73 to the outside of the housing of gearbox 21. A seal for shaft 43 is 
shown schematically at 75. Seals for shaft 51 are shown schematically at 
77 and 79. The housing for gearbox 21 is rendered liquid-tight by seals 
75, 77 and 79 to provide a casing which may be fitted by oil for 
lubrication of bearings and gears. A conventional oil plug 99 gives access 
to the interior of gearbox 21 for adding or draining oil. Of course other 
conventional means could be provided for lubrication to the extent 
lubrication was necessary; alternatively bearings and other parts not 
requiring lubrication could be employed. 
A spur gear 81 is slidably mounted on shaft 43 and splined in a 
conventional manner to cause shaft 43 to rotate with gear 81. As shown in 
FIG. 4, gear 81 is disengaged from, and does not mesh with, gear 63. The 
position of gear 81 shown in phantom lines in FIG. 4 is the engaged 
position where the rotation of shaft 51 causes equal rotation of gear 63 
which in turn rotates gear 81 at approximately twice the rotational speed 
of shaft 51. Thus in the engaged position shaft 53 rotates at 
approximately twice the speed of shaft 51 while shaft 43 is freely 
rotating in the disengaged position for gear 81. 
As best shown in FIGS. 6 and 7, the sliding movement of gear 81 is 
controlled by yoke 85 which is moved laterally by lever 87 through shaft 
89 residing in opening 90 in the housing of gearbox 21. Opening 90 is 
sealed by bushing 91 and O-ring 92. 
Lever 87 is remotely actuated by a hollow-cable-wire motion transmitting 
device or by other suitable means (not shown). 
From the foregoing description and by reference to the drawings it will be 
seen that apparatus according to the invention provides a ground wheel 
takeoff mechanism which is very compact and can be easily installed, 
removed or replaced. The gearbox 21 is located above the vehicle axle so 
that it is not likely to be damaged by striking obstructions and it is not 
generally exposed to water, mud, vegetation or the like as the vehicle 
passes through rough or soggy terrain. At the same time the drive sprocket 
41 is accessible so that the drive chain can be readily removed for 
maintenance or replacement. 
The disengagable gear mechanism not only permits the remote starting and 
stopping of the conveyor and impellers, but also allows the vehicle to be 
transported forward or backward in a substantially freewheeling mode as if 
the power takeoff were not present. While a clutch could be utilized for 
disabling the takeoff drive, the illustrated gear mechanism is preferred 
because it eliminates any possibility of slippage in the engaged position. 
The gears are readily engaged and disengaged because the rotational motion 
of shaft 51 and gear 63 is relatively slow. 
Since the gearbox 21 resides generally within the outline of the oversized 
tires of wheel 15 no substantial widening of the wheel base of the 
fertilizer spreader or other vehicle is necessary to accommodate the 
gearbox mechanism. Of course the wheel takeoff mechanism of the invention 
completely eliminates slippage or mud clogging problems with other systems 
having friction wheels engaging the vehicle tires. Such problems are 
almost impossible to overcome with the friction drive mechanism due to the 
frequent use of such vehicles in wet and muddy fields. With the apparatus 
according to the invention muddy fields conditions create virtually no 
problems with the ground wheel takeoff drive system. It will be understood 
that chain and sprocket covers and other apparatus desired for operator's 
safety have not been illustrated, but may be employed as required in a 
conventional fashion. 
The particular gearing arrangement shown is quite suitable for the purpose, 
but any other equivalent gear mechanism could be substituted. Also the 
connection of the gearbox sprocket 43 to the fertilizer spreader 
geardriver mechanism 13 by way of chain belt drive could be replaced by an 
equivalent power drive mechanism such as gears and shafts or the like. 
Also the specific application of the ground wheel takeoff drive system for 
fertilizer spreaders is illustrative only, an equivalent mechanism could 
be applied to salt and sand spreaders for trucks or in any situation where 
a mechanical rotating power takeoff from a ground wheel is desirable to 
operate equipment on a moving vehicle. To a lesser extent the mechanism 
according to the invention would be suitable to transmit power in the 
opposite direction so that one or more wheels of the vehicle would be 
driven through the chain belt and gearbox from a power source on the 
vehicle. 
In addition to the variations and modification to the invention shown, 
described and suggested herein, other modifications will be apparent to 
those of skill in the art and accordingly the scope of the invention is 
not to be considered limited to the embodiments and modifications shown or 
suggested but is rather to be determined by reference to the appended 
claims.