Speed reducer

The present invention discloses a speed reducer or multiplier for use in a motor grader. The unique structure of the reducer allows the device to be easily inserted in the drive train of a grader and thereby improve the feasible ground speeds at which the grader can operate satisfactorily. The structure further allows the speed of the planetary reduction system to remain idle when not in use. Thereby increasing the efficiency and decreasing problems such as wear. This is accomplished by a shifting mechanism which causes at least two gears to be engaged or disengaged.

FIELD OF THE INVENTION 
The present invention relates to transmissions and more particularly, to 
speed reducers for use in the power train of a motor grader. 
BACKGROUND OF THE INVENTION 
Motor graders are principally designed to be used in road building, 
however, due to their large size and stability, they have been adapted for 
other uses such as bank grading, pavements planning, brush cutting and 
snow blowing. 
As one can appreciate, a grader loses power with age, due to wear, and no 
longer functions at maximum performance. This drop in power is 
particularly noticeable at lower engine r.p.m. and the operators tend to 
compensate for this reduction in power by increasing the engine r.p.m.'s 
and riding the clutch to avoid stalling the engine. 
Although older graders may not be as versatile as new machines, they still 
find spot duty doing many of the lighter jobs such as light roadgrading, 
snow removal etc. In most cases the loss of power could be overcome by 
rebuilding the engine, however, this is normally not a feasible solution 
as other components of the grader have also worn and the reliability of 
the grader would not justify this investment. A number of accessories such 
as snow blowers, pavement planners and pavement rippers are available for 
a grader, however, the grader must be capable of operating at low vehicle 
ground speed and hence, low r.p.m.'s which is not always possible, as the 
power output is low at these engine r.p.m.'s causing the engine to stall 
when the load is applied. 
The present invention overcomes this problem by introducing a speed reducer 
in the power train of the motor grader, such that the grader can operate 
at these reduced ground speeds while providing the required torque. When 
these characteristics are not required, the speed reducer may be 
disengaged returning the drive train to its original status. The device is 
particularly useful as the normal transmission ratios may be used for 
light functions and the speed reducer may be engaged when low ground 
speed, high torque functions are required. For example, the speed reducer 
would not be used when the grader is travelling to the job site, however, 
when on site the speed reducer would be engaged allowing the grader to 
fulfill the desired function. 
SUMMARY OF THE INVENTION 
The specification of the present invention discloses a speed reducer or 
multiplier comprising an input shaft, an output shaft, a planetary gear 
system and a movable power transfer member adapted to selectively engage 
either the input shaft and the output shaft whereby the planetary system 
freely rotates, or the output shaft and the planetary gear system. The 
arrangement is such that the engagement of said transfer member with the 
planetary gear system causes the engagement of the input shaft and the 
planetary gear system thereby changing the speed of the output shaft 
relative to the input shaft. The engagement of the transfer member with 
the input shaft causes the disengagement of the input shaft and the 
planetary system thus providing a non engaged free planetary system. 
The speed reducer according to this design uses a moving transfer member 
which causes the planetary system to be disengaged or engaged at two 
points. Because of this arrangement, the planetary system is allowed to 
freewheel when not engaged thereby, reducing wear and reducing the power 
consumed. 
The speed reducer allows an older motor grader to be modified increasing 
the range of ground speeds in which the grader can operate, thus 
increasing the versatility and useful life of the grader.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
As can be seen in FIG. 1, the speed reducer has an input shaft 1, an output 
shaft 2, a sliding power input member 3, a sun gear 4, planetary gears 5, 
a stationary ring gear 6, planetary gear frame member 8, power transfer 
member 10, power output gear 12 and shifting mechanism 14. 
The casing 20 of the speed reducer has been provided with bearings 21 for 
supporting and positioning the input shaft 1. The power input gear 3, the 
sun gear 4, and planetary gear supporting structure 22 are all carried on 
the input shaft 1. The sun gear and the support structure 22 are bearingly 
supported on this shaft whereas, the power input gear 3 is splined to the 
input shaft such that it can slide in the axial direction of the shaft but 
cannot rotate on the shaft. 
In the positions shown in FIGS. 1 and 3, the planetary gear system is 
coupled to the input and output shafts, thereby activating the speed 
reducer. In this position the power transfer member 10 has been moved 
forward and is meshing with gear 9 which is secured to the frame 8. The 
frame member 8 is connected and driven by the axes of the planetary gears. 
The power transfer member is engaging the power output gear 12 which will 
be the case regardless of whether the speed reducer is activated or the 
power is being directly transmitted through the speed reducer. 
Due to the position of the power transfer member 10, the power input member 
3 has been moved forward on the input shaft 1 such that gear 34 meshes 
with ring gear 30 which is fixed to the sun gear 4. As shown in the 
figures the power input members 3 has two gears, 32 and 34 of different 
diameters. Only one of these gears will be engaged at any one time, gear 
34 transmitting power from the input shaft to the planetary gear system 
and gear 32 transmitting power through the transfer member 10 to the 
output gear 12. 
As shown in FIGS. 2 and 3 a plate member 100 has been secured to the rear 
face of input member 3 enabling the power transfer member 10 to position 
the input member of the splined input shaft. When member 10 is moved from 
the direct drive position shown in FIG. 2 to the planetary gear system 
shown in FIG. 3 the gear teeth 11 of the transfer member 10 strike the 
plate member 100 forcing the input member 3 to slide on the input shaft 
activating the reducer by engaging gears 30 and 34 and disengaging the 
power transfer member 10 and gear 32. The system is returned to the direct 
drive position of FIG. 2 by moving the power transfer member in the 
opposite direction allowing gear teeth 13 to abut the plate member 100, 
moving the input member disengaging gears 30 and 34 and engaging gear 32 
with the power transfer member. 
The transfer member 10 comprises two coaxial ring gear portions 41 and 42 
having gear teeth 11 and 13 respectively. Separating the ring gear 
portions is an annular sleeve 43 having a diameter greater than outer 
diameter of gear 32 and having an axial length greater than the thickness 
of the teeth of this gear, such that gear 32 may turn within the annular 
sleeve when not engaged. 
The ring gear portion 42 is adapted to mesh with either input gear 32 or 
gear 9 secured to the frame member 8; gear 32 and gear 9 being of equal 
diameter. 
As shown in FIGS. 1 and 3, the transfer member 10 has been moved forward, 
forcing gear 34 of the power input member to mesh with the planetary 
system. In this mode, power transferred from the input shaft to the 
planetary system via gears 30 and 34, to the power transfer member via 
gear 9 and subsequently to the output shaft. 
In FIG. 2, the speed reducer is not activated and power is being directly 
transmitted to the output shaft 2. The transfer member 10 has been moved 
by the shift mechanism 14 such that the transfer member is no longer 
meshing with gear 9 and has now engaged gear 32 of the power input member 
3. The movement of the transfer 10 has also caused the power input member 
3 to move a similar axial direction, disengaging ring gear 30 and gear 34 
of the power input member. Power is now transmitted from the input shaft 
to the transfer member 10 via gear 32 and subsequently to the output 
shaft. 
Ring gear 30 and gear 9 of the frame member 8 have been disengaged thereby 
freeing the planetary gear system. It is only through this double 
disengagement caused by the movement of the power transfer member 10 and 
the subsequent movement of the power input member 3 combined with the sun 
gear bearingly supported on the input shaft that the planetary gear system 
may be isolated and not driven with the input shaft. 
As can be appreciated, all functions do not require this higher torque for 
a given speed, and thus the operator must be capable of selectively 
engaging the speed reducer. With double disengagement, the planetary 
system is completely free to rotate, however, due to the friction within 
the system the planetary gear system will have little movement when not 
engaged. 
Functions which require these improved torque characteristics at low speed, 
are often seasonal and therefore, there is no need to have the planetary 
system driven when the speed reducer is not activated, as power 
consumption and wear would increase. 
The torque available at a given ground speed is increased due to the 
transmission of forces within the gear system as well as due to the power 
characteristics of the engine. The speed reducer allows the engine to 
operate at higher r.p.m.'s for a given ground speed and more power is 
available as engine speed initially increases. Therefore more power and 
torque is available due to the characteristics of the engine and speed 
reducer. The increased engine speed also allows other equipment of the 
grader such as the heater to function properly which would not be the case 
if engine speed was low. Thus the speed reducer allows the engine to 
operate within its normal speed range while allowing the ground speed to 
be reduced for speciality jobs. It is normally anticipated that a speed 
reduction of approximately 3 to 1 will operate satisfactorily however, 
other reduction ratios are also possible. A torque arm (not shown) is 
secured to the casing of the speed reducer and secured to the grader 
locking the casing against rotation. 
The transfer member 10 is positioned by the shifting mechanism 14 
comprising a shifting fork 17 secured to connecting rod 19. The transfer 
member 10 has an outwardly facing annular groove for insertion of fork 17. 
The connecting rod will be controlled from the cab of the grader through a 
linkage mechanism allowing the operator to activate the system. The 
annular groove and shifting fork 17 provide a suitable connecting means 
allowing the transfer member to rotate while also allowing the fork member 
to be fixed with respect to rotation. 
In its present application, the speed reducer will normally be positioned 
between the output of the engine and the transmission of the grader and 
therefore, the output shaft 2 has been adapted with a splined free end for 
direct engagement in the transmission of the grader. It is also noted that 
to avoid extensive modification costs the reducer has been designed to be 
as small as possible and only requires a gap of approximately 10 inches 
for insertion. 
In adapting the motor grader, the drive shaft from the engine is shortened 
or replaced and the output shaft of the reducer directly inserted in the 
transmission. Therefore, the present system results in a very compact, 
speed reducer which can be quickly inserted in the power train of a motor 
grader without encountering major modification problems and excessive 
downtimes. 
Because of the unique design of the system the speed reducer can be 
activated when required and at other times, will not be driven as the 
planetary system has been completely disengaged from the input and output 
shafts. Thus the present system is highly reliable and can improve the 
versatility of graders to allow them to satisfy the specialty functions 
required of them. This is particularly true of older motor graders which 
can now be adapted to fulfill these specialty functions in a more 
efficient manner. 
The present invention has been described in relation to one particular 
application of the device, as a speed reducer in a motor grader, however, 
the invention could also be used as a speed multiplier if so desired. If 
used as a multiplier the improved torque characteristics would not be 
present although the double disengagement would still allow the planetary 
system to free wheel when not activated. 
Although various embodiments of the invention have been described herein, 
in great detail, it will be appreciated by those skilled in the art that 
variations may be made thereto, without departing from the spirit of the 
invention or the scope of the appended claims.