Abstract:
A planetary gearbox with substantial speed reduction includes a stationary spindle, an integral service brake, and a parking brake. The integral service brake resides radially outwardly with respect to the parking brake in a stacked arrangement such that axial space is conserved yielding an axially short and compact gearbox. An oil passageway extends radially through the spindle. A rotating input shaft drives the planetary gearbox and produces an output in the form of a rotatable housing/hub. The service brake rotors have a large surface area and are keyed to the rotatable hub enabling efficient brake cooling and efficacious brake performance in a compact arrangement.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention is in the field of a planetary gearbox with an integral service brake. 
       BACKGROUND OF THE INVENTION 
       [0002]    Many off-highway machines are driven by hydraulic motors mounted to planetary wheel drives. Some of these vehicles are capable of speeds of up to 35-40 miles/hour. Due to the large mass of these machines and their relatively high speed, braking is a very important function. 
         [0003]    Braking is usually categorized in two ways: service (dynamic) braking and parking (static braking). On many high-speed off-highway machines, the service braking is handled by a combination of back-driving the hydraulic system and actuating a disc-caliper system on the output of the planetary wheel drive. Parking braking is usually done with a multi-disc wet brake at the input of the planetary wheel drive. This brake is usually spring-applied and released with hydraulic charge pressure. 
         [0004]    There are shortcomings of a disc-caliper service braking system on high-speed off-highway hydraulic machines, namely: 
         [0005]    due to the potential large momentum associated with these machines an external output disc-caliper service brake needs to be very large, which makes it a costly feature; 
         [0006]    an output disc-caliper service brake is exposed to the environment, the environment for many of these machines can be severe and highly corrosive to a brake disc; 
         [0007]    disc-caliper brakes also add considerable mass to a fairly weight sensitive application; and, 
         [0008]    for low to moderate braking, the hydrostatic system is used almost exclusively, this prevents the corrosion from being “wiped off” frequently by the caliper. 
         [0009]    There are also shortcomings to wet, multi-disc input/intermediate service brakes, namely: 
         [0010]    braking torque is transferred through gearing; and, 
         [0011]    the brake becomes inherently long due to limitations in diameter and energy capacity needs; 
         [0012]    To avoid making the assembly longer with input/intermediate brakes, the design would be compromised: 
         [0013]    this would result in a recommendation of one-time use only before replacement; 
         [0014]    may also result in limiting machine speed to reduce the potential energy that the brake may encounter; and, 
         [0015]    the linear velocity of the disc pack is also increased (relative to the velocity of an output brake), this would be a large contributing factor in heat generated within an assembly and would be another reason to decrease machine speed. 
       SUMMARY OF THE INVENTION 
       [0016]    A planetary gearbox with integral service brake and with integral parking brake is disclosed and claimed. The device includes a stationary spindle, a service brake, and a parking brake. The service brake resides radially outwardly with respect to the parking brake. A first oil passageway extends radially from the parking brake to the service brake. 
         [0017]    The service brake operates between the output gear housing which is at or near the radial extent of the device and a stationary spindle. The stator and rotor discs of the service brake has large surface areas because they reside generally toward the radial extent of the device and have large outside diameters and relatively small inside diameters. Additionally, the planetary gearbox provides a large gear reduction resulting in a slow rotation of the output gear housing on the order of 20-30:1. Thus, the output gear housing rotates slowly which prevents the brake from generating excess heat. Still additionally, the rotors and stators used have slits which guide the lubricating oil through the rotors and stators of the service brake. A planetary gear system and a rotating shaft are coupled to the planetary gear system. The planetary gear system drives a rotatable ring gear housing. The service brake operates between the stationary spindle and the rotatable ring gear housing. The parking brake operates between the stationary spindle and the rotating shaft coupled to the planetary gear system. The planetary gear system includes an input stage and an output stage. 
         [0018]    The parking brake includes rotor discs and stator discs. The first oil passageway extends radially from the parking brake to the service brake and resides in the stationary spindle. The first oil passageway extends radially from the parking brake to the service brake and transfers oil from the parking brake to the service brake due to the rotary motion of the rotating shaft and the rotors of the parking brake. The first and second oil passageways reside in the stationary spindle slightly above the oil fill line (the level of the reservoir). However, the first and second oil passageways can have other orientations in the stationary spindle. 
         [0019]    The second oil passageway extends radially from the parking brake to the service brake. The second oil passageway resides in the stationary spindle. The second oil passageway extends radially from the parking brake to the service brake and transfers oil from the parking brake to the service brake due to the rotary motion of the rotating shaft and the rotors of the parking brake. 
         [0020]    An intermediate hub is affixed to the rotatable ring gear housing. The service brake includes service brake rotor discs affixed to the intermediate hub and rotatable therewith. The service brake includes service brake stator discs affixed to the stationary spindle. An input drive shaft and an input sun gear are coupled together. A coupling interconnects the input drive shaft and the input sun gear. The parking brake includes parking brake rotor discs affixed to the coupling and rotatable therewith. The parking brake further includes parking brake stator discs affixed to the stationary spindle. 
         [0021]    The service brake stator and rotor discs comprise a service brake disc stack. A spring-loaded service piston insures disengagement of the service brake disc stack with no pressure applied to the piston. In other words, the service brake spring constantly applies force to the service brake piston such that the service brake is normally “off” which “unlocks” the intermediate hub and the output ring gear housing from the stationary spindle. Still, in further words, the service brake spring urges the service brake piston such that the outer rotational components (the intermediate hub and the output ring gear housing) are not connected to ground (with ground being the stationary spindle). 
         [0022]    Upon the application of hydraulic pressure to the service brake piston cavity, the pressure compresses the spring which causes the piston to engage the rotor and stator discs of the service brake stack locking the rotational components to ground. 
         [0023]    Further, the parking brake stator and rotor discs comprise a parking brake disc stack. A spring-loaded brake piston engages the parking brake disc stack when no hydraulic pressure is applied to the piston. In other words, the parking brake spring constantly applies force to the parking brake piston such that the parking brake is normally “on” which “locks” the coupling and the input shaft to the stationary spindle. Still, in further words, the parking brake spring urges the parking brake piston such that the coupling and the input shaft are connected to ground with ground being the stationary spindle. Upon the application of pressure to the parking brake piston cavity, the spring is compressed and the parking brake piston disengages the brake stack. 
         [0024]    The invention can be alternately described as including a stationary spindle, a service brake, and a planetary gear system. A rotating shaft is coupled to the planetary gear system and, the rotating shaft drives the planetary gear system. The planetary gear system drives a rotatable ring gear housing, and, the rotatable ring gear housing includes a hub. A first oil passageway in the stationary spindle extends radially providing oil to the service brake. The service brake operates between and engages the stationary spindle and the rotatable ring gear housing including the hub. Further, a parking brake provides oil to the first oil passageway in the stationary spindle extending radially to the service brake when the parking brake is not active (when the parking brake is off). 
         [0025]    Still additionally, the planetary gearbox with integral service brake includes a parking brake having rotor discs and stator discs. The rotor discs of the parking brake provide oil to the first oil passageway in the stationary spindle which extends radially to the service brake when the parking brake is not active. 
         [0026]    The planetary gearbox with integral service brake further includes an oil reservoir and the spindle includes an oil return passageway. There are actually three oil return passageways in the spindle illustrated herein. However, the number of oil return passageways may be different depending in other spindles. A service piston is used for applying the service brake. A third oil passageway is formed between the service piston and the hub of the ring gear housing. A main bearing resides between the stationary spindle and the hub of the ring gear housing. The service brake provides oil to the third oil passageway formed between the service piston and the hub of the ring gear housing. The main bearing pumps oil from the third oil passageway to the oil return passageway into the oil reservoir. 
         [0027]    The rotor discs of the parking brake provide oil to the first oil passageway in the stationary spindle which extends radially to the service brake when the parking brake is not active. A second oil passageway in the stationary spindle extends radially and provides oil to the service brake when the parking brake is not active. The rotor discs of the parking brake also provide oil to the second oil passageway in the stationary spindle which extends radially to the service brake when the parking brake is not active. 
         [0028]    The service brake stator and rotor discs comprise a service brake disc stack. A pressure operated spring-loaded service brake piston engages the service brake disc stack upon the application of pressure to the piston. The parking brake stator and rotor discs comprise a parking brake disc stack. A spring-loaded parking brake piston engages the parking brake disc stack upon the application of pressure to the piston. 
         [0029]    The planetary gearbox, stationary spindle and integral service brake have a common axis. The service brake includes rotor discs and stator discs each of which include an outer diameter and an inner diameter. The discs include a large surface area as determined by the inner and outer diameters of the rotor discs and the stator discs with respect to the common axis, respectively. The service brake resides radially outwardly with respect to said common axis. 
         [0030]    Either the rotor discs or the stator discs of the service brake include friction material thereon. The discs include first and second side surfaces, and, the discs include grooves therein for more efficient use of lubricating oil and heat dissipation. 
         [0031]    The instant invention seeks to internalize the service braking while designing the brake at the output of the gearbox. This protects the brake from the environment while overcoming the disadvantages of external output service brakes and internal/intermediate multi-disc wet brakes. The challenge in doing this is to find a way to package the brake without increasing the length of the assembly. Given a common application for this invention is agricultural sprayers, the overall length of the assembly is critical. As the assembly increases in length, there is additional crop disturbance as the machine drives through fields. There are standard crop row widths that the assembly must operate within. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0032]      FIG. 1  is a perspective view of the planetary gearbox with integral service brake. 
           [0033]      FIG. 1A  is another perspective view of the planetary gearbox with integral service brake. 
           [0034]      FIG. 1B  is a right end view of the planetary gearbox with integral service brake. 
           [0035]      FIG. 1C  is a left end view of the planetary gearbox with integral service brake. 
           [0036]      FIG. 2  is a cross-sectional view taken along the lines  2 - 2  of  FIG. 1C  illustrating the service brake and the parking brake, and a port and a passageway supplying the parking brake piston cavity operating the parking brake piston 
           [0037]      FIG. 2A  is an enlargement of a portion of  FIG. 2  illustrating the service brake. 
           [0038]      FIG. 2B  is an enlargement of a portion of  FIG. 2  illustrating the parking brake. 
           [0039]      FIG. 3  is a cross-sectional view of the planetary gearbox with integral service brake taken along the lines  3 - 3  of  FIG. 1C  illustrating, inter alia, radial passageways interconnecting the parking brake and the service brake. 
           [0040]      FIG. 3A  is an enlargement of a portion of  FIG. 3  illustrating the parking and service brake and a radial passageway in the stationary spindle interconnecting the parking brake and the service brake. 
           [0041]      FIG. 3B  is a view similar to  FIG. 3A  except that the parking brake is not engaged and, thus, the parking brake is supplying oil through the stationary spindle to the service brake. 
           [0042]      FIG. 4  is a cross-sectional view of the planetary gearbox with integral service brake taken along the lines  4 - 4  of  FIG. 1C  illustrating, inter alia, a port and a passageway supplying pressure to the service brake piston cavity for operating the service brake piston; in this view, pressure is not being applied to the piston cavity. 
           [0043]      FIG. 4A  is an enlargement of a portion of  FIG. 4  illustrating the service brake, the service brake piston, the parking brake, and the parking brake piston. 
           [0044]      FIG. 4B  is an enlarged view similar to the enlargement of  FIG. 4A  illustrating the parking brake not actuated and the service brake actuated. 
           [0045]      FIG. 5  is a perspective view of the spindle illustrating exterior protrusions/ridges and grooves which prevent rotation of the stator discs operating between the stationary spindle and the rotatable intermediate body/hub. 
           [0046]      FIG. 5A  is a cross-sectional view taken along the lines  5 A- 5 A of  FIG. 5  illustrating the oil return passageways in the spindle. 
           [0047]      FIG. 5B  is a perspective view of the intermediate hub illustrating recesses for engagement with protrusions of the stator discs of the service brake. 
           [0048]      FIG. 6  is a perspective view of the stator and rotor brake discs of the service brake stack. 
           [0049]      FIG. 6A  is an enlarged cross-sectional view of the service brake disc stack taken along the lines  6 A- 6 A of  FIG. 6 . 
           [0050]      FIG. 7  is an enlarged perspective view of the parking brake disc stack. 
           [0051]      FIG. 7A  is an enlarged cross-sectional view of the service brake disc stack taken along the lines  7 A- 7 A of  FIG. 7 . 
           [0052]      FIG. 8  is a perspective view of the coupling. 
           [0053]      FIG. 8A  is a cross-sectional view taken along the lines  8 A- 8 A of  FIG. 8  illustrating grooves and protrusions in the exterior thereof. 
           [0054]      FIG. 9  is a diagrammatic view of the parking brake and the service brake together with the stationary spindle, the rotatable coupling and the rotatable hubs. 
       
    
    
     DESCRIPTION OF THE INVENTION 
       [0055]      FIG. 1  is a perspective view  100  of the planetary gearbox with integral service brake  1 . Reference numeral  1  is used to denote the planetary gearbox with integral service brake. End cover  31  is illustrated on right end of the drawing. End cover  31  is affixed to and rotates with outer ring gear housing  19 L. Oil fill and drain holes  30  are illustrated in the cover  31 . Sometimes herein the outer ring gear housing  19 L is referred to as a hub. Intermediate hub  19 I is affixed to outer ting hear housing by threaded studs  27 S and/or by other connectors. Bearing support  11 M is illustrated in  FIG. 2  and is affixed to the stationary spindle  11 A. Threaded studs  27 S are used to affix a wheel of a vehicle to the planetary gearbox. Holes  50 H are illustrated in stationary spindle  11 A which is bolted to the frame of the vehicle. 
         [0056]      FIG. 1A  is another perspective view  100 A of the planetary gearbox with integral service brake  1 . Motor shaft  40 S inputs power and rotary motion into the gearbox  1 . Pressure supply ports  20 ,  24  are illustrated in  FIG. 1A . Pressure supply port  20  is connected with passageway  20 P which supplies pressure to a parking brake cavity  17 N. See  FIGS. 2 and 2B  which illustrate the parking brake in the actuated position which is the normal, safe position. Pressure is applied in passageway  20  and in parking brake cavity  17 N and acts upon piston  17 A releasing the parking brake and enabling operation of the wheel and, hence, the vehicle. Pressure is preferably applied using hydraulic fluid, however, air pressure or some other fluid may be used. 
         [0057]    Still referring to  FIG. 1A , pressure supply port  24  is connected with passageway  24 P which supplies pressure to a service brake cavity  19 N. See  FIGS. 4 and 4A  which illustrate the service brake  19  in the not actuated condition. In other words, the service brake  19  does not engage the service brake stack comprised of rotor discs  19 C and stator discs  19 D. Stator discs  19 D include protrusions  53  which reside in corresponding grooves  51 G which reside in the exterior of the stationary spindle  11 A. Three portions of the spindle include alternating raised protrusions  51 P and grooves  51 G as set forth in  FIG. 5 . The three portions of the spindle are separated by 120°. It will be understood by those skilled in the art that the spacing and grouping of these portions may be different. In this way, the stator discs  19 D are fixed against rotation with respect to the spindle  11 A. 
         [0058]      FIG. 1B  is a right end view  100 B of the planetary gearbox with integral service brake  1 . An oil fill level is indicated on the cover  31 .  FIG. 1C  is a left end view  100 C of the planetary gearbox with integral service brake  1 . 
         [0059]      FIG. 6  illustrates the service brake stator discs  19 D and the service brake rotor discs  19 C grouped together. Stator discs  19 D include inner protrusions  53  for locking the stator discs to the stationary spindle  11 A. Rotor discs  19 C include protrusions  67  in the shape of a portion of a semi-circle. 
         [0060]      FIG. 2B  is an enlargement  200 B of a portion of  FIG. 2  illustrating the parking brake  17 . Spring  17 D applies force to piston  17 A which engages the parking brake stack. The parking brake stack includes a plurality of rotor discs  17 B which are affixed to coupling  11 . Coupling  11  is illustrated in  FIG. 8  having a series of ridges or protrusions  80 P to which rotor discs  17 B are keyed. Rotor discs  17 B include a series of recesses  81 G as illustrated in  FIG. 7  which interfit ridges/protrusions  80 P of the coupling. In  FIG. 2B , friction material  17 Z is illustrated on the rotor discs  17 B. The friction material is a sintered bronze type. Other friction materials may be used. The friction material  17 Z can be on either the stator discs  17 C or the rotor discs  17 B. Still referring to  FIG. 2B , spring  17 D operates against plate  17 L which is fixed by ring  17 K. Seals  17 G and  17 J are preferably elastomeric seals and are located in unnumbered recesses in stationary spindle  11 A. Seals  17 G,  17 J are adjacent parking brake cavity  17 N and seal parking brake cavity  17 N. Stators  17 C include protrusions  66  which are keyed to recesses  55  in spindle  11 A to prevent rotation of the stators  17 C with respect to the spindle  11 A. See  FIGS. 3A ,  3 B, and  7  which illustrate the protrusion  66 . See  FIGS. 3A and 5A  which illustrate recesses  55 . 
         [0061]      FIG. 6  is a perspective view  600  of the stator  19 D and rotor  19 C brake discs of the service brake stack. Protrusions  66  of the stators  17 C of the parking brake  17  are illustrated in  FIG. 7 . Protrusions  66  mate with recesses  55  of the stationary spindle  11 A as illustrated in  FIG. 5A .  FIG. 6A  is an enlarged cross-sectional view  600 A of the service brake stack taken along the lines  6 A- 6 A of  FIG. 6 . 
         [0062]    Referring to  FIGS. 2 ,  5 B and  FIG. 6 , protrusions  67  of rotor  19 C engage corresponding recesses  65  in the intermediate hub  19 I.  FIG. 5B  is a perspective view  500 B of intermediate hub  19 I. 
         [0063]    Friction material  19 Z is illustrated in  FIGS. 2A and 6A  on rotor disc  19 C. The friction material is a sintered bronze type. Other friction materials may be used.  FIGS. 6 and 6A  illustrate generally spiral shaped slits  19 X in the friction material  19 Z.  FIG. 6A  also illustrates generally radially shaped slits  19 R in the friction material  19 Z. Slits  19 X and  19 R permit lubricating oil to flow therein enabling improved heat transfer. Spirally shaped slits  19 X allow lubricating oil to flow from the inner portion of the spiral to the outer portion of the spiral. The spiral nature of the slits  19 X allows lubricating oil to move more efficiently and more slowly across the side of the rotor disc thus improving heat transfer. Radial slits  19 R allow lubricating oil to move radially outwardly along the slits  19 R. Rotor discs  19 C and stator discs  19 D are illustrated in  FIG. 6A  as being in engagement with one another. 
         [0064]    Portions of the brake parts, the stationary spindle, the gearing, the disconnect plug, and the coupling are made of carbon steel. Other suitable materials may be used. The housings/hubs, cover, and input carrier are made of ductile iron. Other suitable materials may be used. 
         [0065]    Lubrication as described above in connection with slits  19 X and  19 R occurs when the stator discs  19 D and the rotor discs  19 C are separated. First and second oil passageways  22  in the stationary spindle are located horizontally with respect to the earth just above the oil fill level. However, additional oil passageways could be located within the stationary spindle  11 A and be oriented differently with respect to the earth. Referring to  FIG. 2B , when the parking brake  17  is not active, the parking brake stator discs  17 C and rotor discs  17 B are separated each from the other. As the rotor discs  17 B rotate with the coupling  11 , they pick-up oil and move the oil into first and second oil passageways  22  in the stationary spindle  11 A. 
         [0066]      FIG. 2  is a cross-sectional view  200  taken along the lines  2 - 2  of  FIG. 1C  illustrating the service brake  19  and the parking brake  17 , and port  20  and passageway  20 P supplying pressure to the parking brake piston cavity  17 N operating the parking brake piston  17 A. See  FIG. 2B  which shows the parking brake in detail.  FIG. 2A  is an enlargement  200 A of a portion of  FIG. 2  illustrating the service brake  19 . In  FIGS. 2 and 2A , the service brake is not actuated, in other words, no pressure has been applied to the service brake piston cavity  19 N. The service brake piston cavity  19 N is best illustrated in  FIG. 4A .  FIG. 5B  is a perspective view  500 B of the intermediate hub  19 I illustrating recesses  65  for engagement with protrusions  67  of the rotor discs  19 C of the service brake  19 . 
         [0067]      FIG. 2  includes an illustration of the planetary gear system which includes an input stage and an output stage. The input stage is illustrated and includes the input shaft  6 S, sun gear  6 , input planet gears  10 F, input ring gear  7 , and input carrier  10 A. Input carrier  10 A drives the output stage of the planetary gear system. Input carrier  10 A drives the second/output sun gear  10 H which drives the output planet gears  11 H which mesh with output ring gear housing/hub  19 L. 
         [0068]      FIG. 4  is a cross-sectional view  400  of the planetary gearbox with integral service brake  1  taken along the lines  4 - 4  of  FIG. 1C  illustrating, inter alia, port  24  and a passageway  24 P supplying the service brake piston cavity  19 N operating the service brake piston  19 B. 
         [0069]      FIG. 4A  is an enlargement  400 A of a portion of  FIG. 4  illustrating the service brake  19 , the service brake piston  19 B, the parking brake  17 , and the parking brake piston  17 A.  FIGS. 4 and 4A  illustrate the service brake  19  in the normal state which is the “off” condition, or the non-actuated position, or put another way, the disengaged position. Put another way, the rotor discs  19 C and the stator discs  19 D are illustrated in  FIG. 4A  and they are not in engagement with each other. Spring  19 F is a wave spring and it encircles the stationary spindle  11 A. Spring  19 F urges service brake piston  19 B away from the service brake disc stack. By service brake disc stack it is meant the rotors  19 C and the stators  19 D. O-ring seals  19 J,  19 K seal the sealing ring  19 A. O-rings  19 K,  19 K seal the opening leading to the service brake piston cavity  19 N as best viewed in  FIG. 4A . 
         [0070]    Still referring to  FIG. 4A , protrusions  53  of stator discs  19 D are shown and these protrusions reside in one of the grooves  51 G of the stationary spindle  11 A. Service brake piston cavity  19 N is formed between sealing ring  19 A, service brake piston  19 B and the stationary spindle  11 A. Retaining ring  19 E retains thrust washer  19 G and wave return spring  19 F. The service brake  19  normally operates in the disengaged state except when the operator of the vehicle wants to slow or stop the vehicle. In the position illustrated in  FIGS. 4 and 4A , the vehicle is parked as the parking brake  17  is engaged and the service brake piston is shown engaging the brake stack. 
         [0071]      FIGS. 4 and 4A  also illustrate the intermediate hub  19 I affixed to the rotatable ring gear housing/hub  19 L.  FIG. 4B  is an enlarged view  400 B similar to the enlargement of  FIG. 4A  illustrating the parking brake  17  not actuated and the service brake  19  actuated with pressure being applied to the service brake piston cavity  19 N. In the condition illustrated in  FIG. 4B , the vehicle is stopped or slowing and the parking brake has been released and is not activated or engaged and pressure has been applied to parking brake piston cavity  17 N. 
         [0072]      FIG. 5  is a perspective view  500  of the spindle  11 A illustrating exterior ridges or protrusions  51 P and grooves  51 G between the protrusions. The protrusions  51 P and grooves  51 G prevent rotation of the stator discs  19 D operating between the stationary spindle  11 A and the rotatable intermediate hub  19 I. Reference is made to  FIG. 6  illustrating protrusions  53  of the stator discs  19 D of the service brake  19 . 
         [0073]    Referring again to  FIG. 5 , one of the oil passageways  22  in the stationary spindle  11 A is illustrated. The unnumbered openings in the right portion of the spindle illustrated in  FIG. 5  accommodate the output planet gears  11 H which are mounted therein.  FIG. 5A  is a cross-sectional view  500 A taken along the lines  5 A- 5 A of  FIG. 5  illustrating the oil return passageways  22 A,  22 B, and  22 C in the spindle  11 A.  FIG. 5B  is a perspective view  500 B of the intermediate hub  19 I illustrating recesses  65  for engagement with protrusions  67  of the rotor discs  19 C of the service brake  19 . 
         [0074]    As stated above,  FIG. 2  is a cross-sectional view  200  taken along the lines  2 - 2  of  FIG. 1C  illustrating the service brake  19  and the parking brake  17 , and port  20  and a passageway  20 P for supplying pressure to the parking brake piston cavity  17 N operating the parking brake piston  17 A. In  FIG. 2  there is not pressure in cavity  17 N. See  FIG. 2B  for an enlarged view.  FIG. 2  illustrates the motor drive shaft  40 S which is supported by bearings or some other support system not illustrated herein. Motor shaft  40 S is splined to coupling  11 .  FIG. 8  illustrates coupling  11 , internal spline  11 S, and exterior protrusions  80 P and exterior grooves  80 G. The exterior protrusions  80 P and grooves  80 G are in a mating arrangement with the rotor discs  17 B of the parking brake  17 . Parking brake  17  is illustrated best in  FIGS. 2B and 3A . 
         [0075]    Spindle  11 A includes flange  50  and bolt holes  50 H in the flange for securing the spindle to the frame of the vehicle. Seal  11 B resides intermediate spindle  11 A and intermediate hub  19 I and prevents dust and debris from entering bearing  11 C and other components. Intermediate hub  19 I is illustrated in  FIG. 5B  and illustrates recesses  65  which receive correspondingly shaped protrusions  67  of the rotor discs of the service brake  19  which interfit the recesses  65 . In this way, rotors  19 C rotate with hubs  19 I,  19 L. 
         [0076]    Studs  27 S affix intermediate hub  19 I to output ring gear housing  19 L. Additionally, studs  27 S interconnect the wheel of the vehicle to the intermediate hub  19 I and to the output ring gear housing  19 L. Service brake piston  19 B is viewed in  FIG. 2  and is best viewed in  FIG. 2A . Output ring gear  5  is splined  23 S to output ring gear housing  19 L. 
         [0077]    Output planet gears  11 H are supported by output planet shaft  11 N which is mounted in the stationary spindle  11 A. Bearing carrier/support  11 M is affixed to the stationary spindle  11 A with bolts (not shown) and secures the rotatable components of the planetary gearbox and integral service brake to the stationary spindle enabling them to rotate therearound. 
         [0078]    Still referring to  FIG. 2 , output planet thrust washers  11 J,  11 K secure the output planet gear  11 H for controlled rotation about output stage needle bearings  11 R and output planet shaft  11 N. Bolts  35  secure the cover  31  to the output gear housing  19 L. 
         [0079]      FIG. 2  illustrates the input shaft  6 S splined to coupling  11 . Input planet gears  10 F are mounted about input planet shaft  10 D on needle bearing  10 C. Input planet shaft  10 D is mounted to input planet carrier  10 A and the input planet gears  10 F rotate therearound. Input shaft  6 S includes a first sun gear  6  in meshing engagement  39 M with input planet gears  10 F. Input planet gears  10 F are in meshing engagement with input ring gear  7  and react thereto driving carrier  10 A. In the example of  FIG. 2 , there are three input planet gears. Input ring gear  7  is splined  25 S to cover  31 .  FIG. 2  also illustrates cover  31  and several oil fill or drain plugs therein  30 . Retaining ring  32  secures the disconnect plug  34  and O-ring  33 . 
         [0080]    Still referring to  FIG. 2 , roll pin  10 E secures the input planet shaft  10 D to the input planet carrier  10 A. Retaining ring  10 G secures the input planet carrier  10 A to the output sun gear  10 H. Input planet carrier  10 A is splined  10 X to output sun gear  10 H and the output sun gear rotates therewith. Thrust washers  10 B secure the needle bearings  10 C to shaft  10 D. 
         [0081]    Output sun gear  10 H is in meshing engagement  37 M with output planet gears  11 H. Output planet gears do not orbit within the gearbox, rather, they are mounted on output planet shafts  11 N and corresponding needle bearings  11 R. In the example of  FIG. 2 , there are three output planet gears  11 H. Output planet gears  11 H mesh with the output ring gear  5  which is splined  23 S to the output housing. Output planet gears  11 H drive output ring gear housing/hub  19 L and intermediate hub  19 I. 
         [0082]      FIG. 7  is an enlarged perspective view  700  of the parking brake stack  17 . Protrusions  66  which mate with recesses  55  in the stationary spindle  11 A are illustrated in  FIG. 7 .  FIG. 7  further illustrates protrusions  81 P and grooves  81 G which interfit with grooves  80 G and protrusions  80 P, respectively. 
         [0083]      FIG. 7A  is an enlarged cross-sectional view  700 A of the service brake stack taken along the lines  7 A- 7 A of  FIG. 7 . Stator discs  17 C and rotor discs  17 B are illustrated in  FIG. 7A  along with the friction material  17 Z on the rotor discs  17 B. The friction material  17 Z can be on either the stator discs  17 C or on the rotor discs  17 B. Spiral shaped slits  17 X are included in the rotor discs  17 B. Radial slits  17 R are also in the rotor disc  17 B. 
         [0084]      FIG. 8  is a perspective view  800  of the coupling  11 .  FIG. 8  illustrates an internal spline  11 S to which input shaft  6 S is connected and to which motor shaft  40 S is connected.  FIG. 8A  is a cross-sectional view taken along the lines  8 A- 8 A of  FIG. 8  illustrating grooves  80 G and protrusions  80 P in the exterior thereof. 
         [0085]      FIG. 9  is a diagrammatic view  900  of the parking brake  17  and the service brake  19  together with the stationary spindle  11 A, the rotatable coupling  11  and the rotatable hubs  19 I,  19 L. This diagrammatic view is taken in consideration of the condition illustrated in  FIG. 3B  where both the service brake  19  and the parking brake  17  are not actuated and their respective disc stacks are not engaged. In the illustration of  FIGS. 3B and 9 , oil flow outwardly is represented by the unnumbered arrows in  FIG. 9 . Rotatable coupling  11  includes ridges or protrusions  80 P and grooves  80 G as shown in  FIG. 8 . Protrusions  80 P interfit corresponding grooves  81 G of the rotor discs  17 B of the parking brake  17  as shown in  FIG. 7 . Protrusions  81 P of the rotor discs of the parking brake interfit grooves  80 G of the coupling  11 . Parking brake stator discs  17 C include protrusions  66  which interfit recesses  55  in the stationary spindle  11 A as shown in  FIGS. 5A and 7 . Service brake stator discs  19 D include protrusions  53  which interfit grooves  51 G of the stationary spindle  11 A as shown in  FIGS. 5 and 6 . Passageways  22  transport oil through the stationary spindle  11 A. Service brake rotor discs  19 C include protrusions  67  which interfit grooves  65  in rotatable hub  19 I as shown in  FIGS. 5B and 6 . Oil exits along a passageway at the interface between the service brake  19  and the rotatable hub  19 I to bearing  11 C where it is pumped by the bearing to an oil return passageway into the oil reservoir as shown in  FIG. 2 . The oil reservoir extends from the bottom of the gearbox to approximately the oil fill line. 
         [0086]    A double planetary gearbox with an output rotatable ring gear housing/hub  19 L is disclosed in the various drawing views. This type of gearbox operates by taking a rotational input from the motor shaft  40 S. The shaft  40 S is driven by a motor (not shown) and is coupled to the coupling  11 . The coupling  11  is coupled to the input shaft  6 S. The input shaft  6 S includes a sun gear  6 . The motion of the sun gear  6  is transmitted through an input planetary stage having input planet gears  10 F and an output planetary stage having output planet gears  11 H. These planetary stages transmit motion to the ring gears  5 ,  7  which are rigidly connected to the intermediate hub  19 I and the housing  19 L. The intermediate hub  19 I and the housing  19 L are affixed together. 
         [0087]    The vehicle&#39;s wheel is attached to the intermediate hub  19 I and the ring gear housing  19 L. When transmitting power through the first and second planetary stages, the output speed is reduced and the output torque is increased by the same ratio. 
         [0088]    The service brake is housed between the spindle  11 A which is connected to the frame of the vehicle and the intermediate hub  19 I. The wheel of the vehicle is connected to the intermediate hub  19 I by threaded studs  27 S and nuts. One of the main wheel bearings  11 C is mounted on the outer part of the spindle  11 A and supports the intermediate hub  19 I. Another main wheel bearing  11 C is mounted between bearing support  11 M and output ring gear housing  19 L. Output ring gear housing  19 L is bolted to intermediate hub  19 I. Both bearings  11 C,  11 C support the intermediate hub  19 L and ring gear output housing  19 L. Since the wheel of the vehicle is rigidly attached to the intermediate hub  19 I by the studs  27 S and nuts, the main wheel bearings  11 C,  11 C support any loading imparted to wheel of the vehicle. 
         [0089]    The service brake includes: a plurality of stators  19 D; a plurality of rotors  19 C; a service piston  19 B; a service piston return spring  19 F; and, a sealing ring  19 A. 
         [0090]    The parking brake includes: a plurality of stators  17 C; a plurality of rotors  17 B; a parking piston  17 A; and, a plurality of piston application springs  17 D. 
         [0091]    Springs  17 D apply force to the parking piston  17 A which in turn applies a force to a stack of alternating rotors  17 B and stators  17 C. The stators  17 C are coupled to the spindle  11 A and the rotors  17 B are coupled to the coupling  11 . Friction material can be on either the rotor  17 B or stator  17 C. This material is specially designed to prevent relative motion between the rotor and stator surfaces when a force is applied to the combination of alternating stators and rotors. By preventing motion between the rotors and stators, the coupling  11  is locked to the spindle  11 A which prevents any motion from taking place in the planetary wheel drive. 
         [0092]    To release the brake, hydraulic charge pressure is applied to the parking release port  20 . This pressurizes the parking brake piston cavity  17 N and imparts a force on the parking piston that compresses the springs  17 D and allows the rotors  17 B and stators  17 C to separate. This allows the coupling  11  to rotate and impart motion through the system. 
         [0093]      FIG. 3  is a cross-sectional view  300  of the planetary gearbox with integral service brake  1  taken along the lines  3 - 3  of  FIG. 1C  illustrating, inter alia, radial oil passageways  22  in the stationary spindle  11 A interconnecting the parking brake  17  and the service brake  19 . As illustrated there are two oil passageways  22  in the stationary spindle. Oil passageways  22  are referred to as the first and second oil passageways. 
         [0094]    Lubricated spinning objects naturally pump oil from their inside diameter to their outside diameter due to the force imparted on the fluid. The same happens within wet disc brakes. When the vehicle is moving, the parking brake  17  pumps oil from its inside diameter to its outside diameter. When the oil is pumped to the outside diameter of the parking brake disc pack it travels through oil passageways  22  and supplies lubricant/oil to the service brake and heat is removed from the service brake  19 . Third oil passageway  26  leads from the service brake  19  to the left most bearing  11 C in  FIG. 2 . Also see the much larger fourth oil passageways  26 A in  FIG. 5B  for supplying oil directly to the left most bearing  11 C. Fourth oil passageways  26 A comprises wide arc-shaped recesses in the intermediate hub  19 I which supply lubricating oil directly to the left most bearing  11 C. Third oil passageway  26  is supplied with oil from the rotor discs  19 C of the service brake  19 . 
         [0095]    Fourth oil passageways  26 A are illustrated in  FIG. 5B . Two fourth oil passageways  26 A are illustrated in  FIG. 5B . However, there are actually four fourth oil passageways  26 A in this example of the intermediate hub  19 I illustrated in  FIG. 5B . There can be more or fewer fourth oil passageways  26 A if desired. Left most bearing  11 C in  FIG. 2  pumps oil to oil return passageways  22 A,  22 B and  22 C illustrated in  FIG. 5A  allowing oil to escape the service brake disc stack  19 C,  19 D to minimize parasitic losses that generate heat. 
         [0096]    Additional first and second oil passageways  22  through the stationary spindle above the oil line may be added. In the example of  FIGS. 3 and 3A , the parking brake  17  is actuated and no lubricating oil is being supplied to the first and second oil passageways  22  in the stationary spindle. 
         [0097]      FIG. 3A  is an enlargement  300 A of a portion of  FIG. 3  illustrating the parking and service brake and a radial oil passageway  22  interconnecting the parking brake and the service brake. 
         [0098]      FIG. 3B  is a view similar to  FIG. 3A  except that the parking brake is not engaged and, thus, the parking brake  17  is supplying oil through the stationary spindle to the service brake  19  and when the vehicle is running. 
         [0099]    Additionally, the rotor  19 C at the end of the disc stack is trapped between the ring gear housing  19 L and the intermediate hub  19 I. Protrusions  66  in the rotor  19 C at the end of the disc stack is interconnected to intermediate hub  19 I via recesses  68  in the intermediate hub  19 I. See  FIG. 5B  illustrating recesses  68  which are slightly out of phase with recesses  65  (for example, not aligned with recesses  65 ). This prevents the service brake  19  disc pack from being slightly engaged when running clearances are reduced as oil is pumped against the last rotor  19 C in the disc stack from adjacent gear meshes  36 M. 
         [0100]    When service braking is required, the machine operator will press his or her foot onto the brake pedal. The pedal is interlocked to the hydrostatic system which creates a negative torque at the motor shaft to begin slowing down the vehicle. In addition, pressure is delivered to the service brake port  24 . The pressure will depend on how far the brake pedal is pushed down by the operator&#39;s foot. The service brake port delivers pressure to the service brake cavity  19 N. Due to the pressure, the service piston moves and imparts a force on the rotors  19 C and stators  19 D. 
         [0101]    While braking, heat is developed due to relative motion and friction forces between the rotors  19 C and stators  19 D. Part of this heat is absorbed into the lubricant and adjacent components. The rest of the heat is absorbed by the brake components. The invention utilizes discs with very large inner and outer diameters that are capable of absorbing heat so that the temperature in the brake cavity does not reach a destructive level. Additionally, since the service brake  19  is located radially outwardly from the common axis of the planetary gearbox, the circumference of the service brake  19  is large. Put another way, the service brake is adjacent to and engages the hub  19 I. This location maximizes the size of the brake for a given thickness as measured from the inside diameter to the outside diameter of the disc stack (rotor discs and stator discs). Additionally, the service brake enjoys a substantially reduction in angular velocity due to the large reduction of the planetary gearbox. Still additionally, since the service brake  19  is located radially outwardly from the common axis of the planetary gearbox, a considerable portion of the service brake is located below the oil line.  FIG. 1  illustrates the preferred oil line on cover  31 . After the braking cycle is complete, the heat will further be dissipated into the lubricants and adjacent components until the temperatures equalize. 
         [0102]    When the brake cycle is complete, and the operator removes his or her foot from the brake pedal, the pressure is removed from the service brake cavity and the return spring  19 F pushes the service piston  19 B back to its original position. This allows the rotors  19 C and stators  19 D to regain their original clearances that they had prior to the brake cycle. Slits  19 X and  19 R enable cooling by controlling lubricant as it flows from inside diameter to the outside diameter of the rotor discs. 
         [0103]    The geometry of this assembly provides several advantages. First the service brake is packaged between the main bearing  11 C and output planet gear  11 H in such a way that limits/prevents any effect of the overall length of the planetary gearbox assembly. The gearbox geometry also takes advantage of the natural tendency of the parking brake to pump oil to cool the service brake. Furthermore, the service brake solves the problems associated with external output brakes and internal input/intermediate multi-disc wet brakes that were previously mentioned. 
       REFERENCE NUMERALS 
       [0000]    
       
           1  arrow pointing to planetary gearbox with integral service brake and parking break 
           4  output sun thrust washer 
           5  output ring gear 
           6  sun gear 
           6 S input shaft of input sun gear  6   
           7  input ring gear 
           10 A input planet carrier 
           10 B input planet thrust washer 
           10 C input stage needle bearing 
           10 D input planet shaft 
           10 E roll pin 
           10 F input planet gear 
           10 G retaining ring 
           10 H output sun gear 
           10 X spline connection of input planet carrier  10 A and the output sun gear  10 H 
           11  coupling 
           11 A spindle 
           11 B lip seal between spindle  11 A and intermediate hub  19 I 
           11 C main bearing 
           11 H output planet gear 
           11 J,  11 K output planet thrust washer 
           11 M bearing carrier/support for one of the main bearings  11 C 
           11 N output planet shaft 
           11 R output stage needle bearing 
           11 S coupling spline 
           11 Z outer boot seal for sealing between spindle  11 A and intermediate hub  19 I 
           17  arrow pointing to the parking brake 
           17 A parking brake piston 
           17 B parking brake rotor 
           17 C parking brake stator 
           17 D parking brake spring for applying the parking brake to the brake disc stack 
           17 G, J o-ring 
           17 K retaining ring 
           17 L parking brake spring reaction plate 
           17 N parking break piston cavity 
           17 X generally spiral shaped slits in the friction material  17 Z 
           17 R generally radially shaped slits in the friction material  17 Z 
           17 Z friction material on rotor disc  17 C of service brake 
           18  identification plate 
           19  arrow pointing to the service brake 
           19 A sealing ring 
           19 B service brake (dynamic brake) piston 
           19 C service brake (dynamic brake) rotor 
           19 D service brake (dynamic brake) stator 
           19 E retaining ring 
           19 F dynamic piston return spring 
           19 G dynamic brake thrust washer 
           19 H,  19 J,  19 K o-ring 
           19 I intermediate hub affixed to ring gear housing  19 L 
           19 L rotatable ring gear housing/hub 
           19 N piston cavity 
           19 X generally spiral shaped slits in the friction material  19 Z 
           19 R generally radially shaped slits in the friction material  19 Z 
           19 Z friction material on rotor disc  19 C of service brake 
           20  port for the supply of pressure to parking brake piston  17 A 
           20 B retaining ring-external 
           20 C retaining ring 
           20 P passageway in spindle  11 A connecting port  20  and parking brake cavity 
           21  o-ring 
           22  first and second oil passageways extending radially through stationary spindle  11 A from the parking brake disc stack to the service brake disc stack 
           22 A,  22 B,  22 C oil return passageways for receiving oil pumped by main bearings  11 C 
           23 S spline connection of output ring gear  5  and ring gear housing  19 L 
           24  port for the supply of pressure to service brake piston  19 B 
           24 P passageway in spindle  11 A connecting port  24  and service brake cavity 
           25 S spline connection of input ring gear  7  and cover  30   
           26  third oil passageways from radial extent of service brake rotors and stators and between the service brake piston and the intermediate hub  19 I 
           26 A fourth oil passageways in the intermediate hub  19 I for supplying lubricating oil directly to left most bearing  11 C for pumping by the bearing 
           27 H bolt hole in intermediate hub  19 I 
           27 S threaded studs 
           30  oil fill 
           31  cover 
           32  retaining ring 
           33  o-ring 
           34  disconnect plug 
           35  bolts affixing cover  31  to the rotating housing  19 L 
           36 M meshing of the output planet gear  11 H and output ring gear  5   
           37 M meshing of the output sun gear  10 H and output planet  11 H 
           38 M meshing of the input planet  10 F and the input ring gear  7   
           39 M meshing of the input sun  6  and the input planet  10 F 
           40 S motor shaft 
           50  flange of spindle  11 A 
           51  ridges on the exterior of the spindle  11 A 
           50 H holes in spindle flange  50   
           53  protrusions on stators  19 D of service brake  19  for engagement with ridges  51  on the exterior of stationary spindle  11 A 
           55  recess in spindle  11 A for receiving protrusions  66  of stator  17 C 
           65  recess in intermediate hub  19 I for receiving protrusions  67  of rotor  19 C of service brake  19   
           66  protrusions on stator discs  17 C of parking brake which engage recesses  55  in spindle  11 A 
           67  protrusions on rotor discs  19 C which engage recesses  65  in the intermediate hub  19 I for rotation therewith 
           68  recess in intermediate hub  19 I for receiving protrusions  67  of rotor  19 C of service brake  19   
           80 G groove in coupling  11   
           80 P protrusion of coupling  11   
           81 G groove in rotor disc of parking brake  17   
           81 P key on rotor disc of parking brake  17   
           100  perspective view of the planetary gearbox with integral service brake 
           100 A another perspective view of the planetary gearbox with integral service brake 
           100 B first end view of the perspective view of the planetary gearbox with integral service brake 
           100 C second end view of the perspective view of the planetary gearbox with integral service brake 
           200  cross-sectional view taken along the lines  2 - 2  of  FIG. 1C  illustrating the service brake and the parking brake, and a port and a passageway supplying the parking brake piston cavity operating the parking brake piston 
           200 A enlargement of a portion of  FIG. 2  illustrating the service brake 
           200 B enlargement of a portion of  FIG. 2  illustrating the parking brake 
           300  cross-sectional view taken along the lines  3 - 3  of  FIG. 1C  illustrating, inter alia, radial passageways interconnecting the parking brake and the service brake 
           300 A enlargement of a portion of  FIG. 3  illustrating the parking and service brake and a radial passageway interconnecting the parking brake and the service brake 
           300 B view similar to  FIG. 3A  except that the parking brake is not engaged and, thus, the parking brake is supplying oil through the stationary spindle to the service brake 
           400  cross-sectional view taken along the lines  4 - 4  of  FIG. 1C  illustrating, inter alia, a port and a passageway supplying the service brake piston cavity operating the service brake piston 
           400 A enlargement of a portion of  FIG. 4  illustrating the parking brake and the piston brake 
           400 B enlargement illustrating the parking brake  17  and the service brake  19  actuated for example, and the respective rotor discs and stator discs of each brake stack are engaged. 
           500  perspective view of the spindle illustrating exterior ridges which prevent rotation of the stator plates operating between the spindle and the intermediate body 
           500 A cross-sectional view of the  FIG. 5  taken along the line  5 A- 5 A 
           500 B perspective view of the intermediate hub  19 I illustrating recesses  65 ,  68  for engagement with protrusions  67  of the rotor discs  19 C of the service brake  19   
           600  perspective view of the stator and rotor brake discs of the service brake stack 
           600 A enlarged cross-sectional view of the service brake stack taken along the lines  6 A- 6 A of  FIG. 6   
           700  enlarged perspective view of the parking brake stack 
           700 A enlarged cross-sectional view of the service brake stack taken along the lines  7 A- 7 A of  FIG. 7   
           800  perspective view of the coupling 
           900  diagrammatic view of the parking brake and the service brake together with the stationary spindle, the rotatable coupling and the rotatable hubs 
       
     
         [0219]    Those skilled in the art will understand that the invention has been set forth by way of example and that changes may be made to the invention as set forth herein without departing from the spirit and the scope of the claims as set forth herein.