Abstract:
A self-propelled stump cutting apparatus which also functions as a tow-behind type, resultant of a telescoping tongue hitch. The apparatus is narrowed in width, while in work mode with tow wheels suspended above ground by removing the detachable tow wheel assemblies. Self-propulsion is accomplished by the employment of a unique, retractable, hydraulically motivated tractor axle assembly. This assembly is located on a hinged sub-frame attached to the apparatus main frame. The tractor axle assembly is forcibly positioned and locked by way of a mechanical assembly which is motivated by the vertical movement of the hydraulically maneuvered cutting wheel boom. A major additional feature is the novel direct coupling of the cutting wheel driving hydraulic motor to the cutting wheel axle shaft. This is accomplished by the employment of a compact, self-aligning internal shaft coupling which eliminates commonly used costly and inefficient belt drive systems.

Description:
[0001]     Cross reference to related application. This application claims the benefit of provisional patent application No. 60/626,095; filed 11-8-2004 by Donald W. Dubbs. 
     
    
     BACKGROUND  
       [0002]     This invention generally pertains to motorized tree stump cutting or grinding devices. Most of these devices are either towed or tailored behind a standard commercial vehicle. Most towed-behind devices are positioned for work by the tow vehicle. Such an arrangement performs well for easy access tree stumps but is not practical in more difficult, tight access applications. The trailer-mounted devices are commonly self-propelled and more compact for tight maneuvering. Their compactness and general high center of gravity make them unstable for high speed towing, hence tailoring is a must.  
         [0003]     These two general types of stump cutters almost all feature a rotating cutting wheel mounted on a boom which is swept from side to side, and up and down by either manual or hydraulic enhanced force. Typically, the cutting wheel-boom assembly is attached to an elongated main frame with a gasoline or diesel engine providing the necessary power.  
         [0004]     It becomes apparent that both of these types of stump cutters have inherent advantages and disadvantages. Hence, it follows that a hybrid device that incorporates said advantages and eliminates said disadvantages would prove to be optimal and therefore superior.  
         [0005]     As to the general rules or types cited there are two notable exceptions. First, the variable width, self-propelled stump cutter U.S. Pat, No. 4,590,183 issued to D. Eilertson on Sep. 1, 1987. Due to a high center of gravity this device requires a trailer. Width varies from narrow for tight maneuvering to wider to stabilize the device for the stump cutting function. The second is the variable width device U.S. Pat. No. 5,289,859 issued to J. Minton Jr. and J. Barr on Mar. 1, 1994. This device requires no trailer and is capable of variable width. The method utilized to vary width does not remove the device&#39;s weight from the tow wheels during transition. It relies on hydro-mechanical force to accomplish transition. This practice is less than optimal when durability, weight and cost consideration are made. Although these devices display advantages they both are less than optimal overall and are lacking several other advanced features.  
         [0006]     As a result, it is concluded that the most desirable stump cutting device would be a hybrid of the two most common types available. Again, those are the tow-behind with wide track and extendable tongue and the self-propelled narrow track type. The hybrid must be variable width and self-propelled. Other advantages featured would include a fixed level mounted engine, enclosed machinery housing and ride-on capability to mention just a few.  
       SUMMARY  
       [0007]     The invention; an economical, variable width, extendable tongue, self-propelled stump cutter is capable of being deployed in nearly all situations. These broadened parameters are accomplished primarily due to a unique, advanced carriage. Additionally, the invention features a hydraulically driven cutting wheel, a sheet metal machinery enclosure with an integral top mounted tote tray/hot air ducting system and running board for ride-on capability.  
         [0008]     The carriage consists of a main frame with a plurality of subassemblies attached. The main frame comprised by square tubing arranged to be run longitudinally to a transfer header with two tangentially mounted tubes attached for use as stub axle receptacles. Directly attached to the primary structural members of the main frame are cylinder mounts, jack or strut mount knuckle pivot boss and tractor axle frame position locks.  
         [0009]     The first subassembly is comprised of the hydraulically motivated boom with a pivoting member, the knuckle, at one end and the hydraulically driven cutting wheel at the other. Undercarriage mounted, tandem hydraulic cylinders pivot the boom assembly from side to side. Up and down movement of the assembly is accomplished by a single hydraulic cylinder linked between the knuckle and the boom.  
         [0010]     Next is the unique pivoting tractor axle subassembly. This arrangement consists of a tractor axle with drive wheels and a chain drive linked to a hydraulic motor. The axle and motor are carried by a trussed sub-frame that is hinged to the underside of the main frame. This sub frame is locked in either the up or the down position while being towed or down while in the self-propelled work mode. Locking is accomplished by lever actuated links with pins that engage cleated plates fixed to the main frame. Up and down motivation is provided by a lever controlled bracket that links the tractor subassembly to the boom. Very economically, the up and down movement of the boom is utilized to raise and lower the entire machine via the tractor axle subassembly.  
         [0011]     An experienced operator can make the transition from tow mode to work mode very quickly. This is to say that this device features not only high mobility, but rapid deployment also.  
         [0012]     The two stub axles for towing and stability are the next subassemblies. These assemblies consist of tubular members that are connected by hitch pins to the tangential receptacles on the main frame. The projecting ends of these members are fitted with the necessary wheels, spindles, hubs and fenders. When the tractor axle is lowered, the stub axle assemblies are raised beyond ground contact. Should a narrow tract be desired, it is a simple matter to manually remove the hitch pin and telescope away the stub axles. Once the stub axle assemblies are detached, the overall width of the device is dramatically narrowed. Thus, the invention is a very economical, variable width, hybrid stump cutter. Note: The device has an inherent, relatively low center of gravity. Still, the narrow mode of operation is only utilized when necessary.  
         [0013]     Another subassembly is the machine housing. This is comprised of a light structural frame, engine, oil pump wit drive, oil and gas tanks, battery and hydraulic controls. All of these components are enclosed by a sheet metal body with an integral tote tray/heat duct top. The enclosure functions to keep the bulk of the device clean and out of harms way. It also makes for an attractive appearance and provides a very significant surface area for advertising.  
         [0014]     Still another subassembly is the ride-on platform or running board. It is positioned on the side of the main frame behind the equipment housing convenient to the tractor axle direction and speed controls. It is also convenient to the steering tiller. This is an asset to the device that further contributes to the promise of rapid deployment and withdraws. The time saved here tends to negate the need for excessively large engines and their additional weight.  
         [0015]     This improved stump cutting machine also features a unique hydraulic system. Almost all prior art utilizes hydraulic pumps, motors and cylinders in association with electric or mechanical clutches which are expensive and tend to pose reliability problems. The presented device is simplified by the use of two uncommon values.  
         [0016]     The first is the flow priority valve which divides the pumps output into two circuits. The low pressure circuit is prioritized thereby boom cylinder speeds are constant regardless of engine speed. Also, on this priority circuit is the tractor motor. Speed of the tractor motor is adjusted by a flow control valve.  
         [0017]     The secondary circuit is dedicated to the driving of the cutting wheel. It features varying high pressures and flows that are relative to engine output, minus power required by the priority circuit that is fixed at all times.  
         [0018]     These unique conditions enable the application of a simple in/out type flow selector valve to function as a clutch. This design provides a simple, low cost, reliable means of power transmission previously unknown to prior art.  
         [0019]     In conclusion the invention is a rapid deploying, light, economical, variable width, tow behind, self-propelled stump cutter with ride-on capability and provisions for tool and material carrying that is unique and highly advantageous in virtually all considerations.  
     
    
     DRAWINGS  
       [0020]      FIG. 1  is a side view of a stump cutting machine in work mode and in accordance with the present invention. Note, belt guard, facing wheels and equipment housing side door is removed for clarity.  
         [0021]      FIG. 2  is a side view of the stump cutting machine of  FIG. 1  showing said machine in tow mode.  
         [0022]      FIG. 3  is a plan view of the stump cutting machine of  FIG. 1  in the work mode.  
         [0023]      FIG. 4  is an isometric view showing the components of the raising and lowering mechanism of the stump cutting machine of  FIG. 1 .  
         [0024]      FIG. 5  is a block diagram of the hydraulic system utilized by the stump cutting machine of  FIG. 1 .  
         [0025]      FIG. 6  is a sectional view of the direct cutting wheel drive with a self-aligning coupling.  
     
    
     DETAILED DESCRIPTION  
       [0026]      FIGS. 1, 2  and  3  illustrate an improved stump grinding machine  10  posing a general image of the presented invention. This device is composed of a main frame  15  and a plurality of subassemblies: 
        A. main frame  15      B. telescoping tongue  25      C. boom with cutting wheel  35      D. pivoting tractor axle with frame  55      E. towing wheels and stub axles  75      F. machine housing  90      G. ride-on platform  115      H. hydraulic system  125           
         [0035]     The following detailed description is categorized to insure clarity to anyone of ordinary skill. 
        A. The main frame  15  is constructed of square metallic tubing with various plate brackets and gussets attached. It also has a round pivot boss for boom assembly attachment and round cylinder attachment pins. A single rail  16  runs longitudinally low on the machine  10  to a transverse header  17 . At this junction a boom pivot boss is fitted  18 . Top and bottom reinforcement gussets  19  are employed at this critical juncture. The header  17  runs laterally equidistant to a pair of tangential tubes  20  that are receptacles for the stub axle wheel assemblies  75 . Also, there are notched lock down brackets  21  attached to the header for locking the tractor axle and frame assembly  50  into the desired position. Additionally, to the underside of the frame members  21  are the pivot brackets  22  that hinge the tractor axle frame assembly  55 , the cylinder mounts  23  that secure the tandem cylinders  38  and the jack or strut mount  24  used in storage and hitching if required by the operator.     B. The telescoping tongue assembly  25  consists of an elongated tubular member  26  that recesses into the main frame rail  16 . A series of holes in the tongue rail  26  allows for a hitch pin  27  to be removed enabling the machine  10  to, by utilization of tractor axle assembly  55 , to perform as a common tow-behind stump cutter. The tractor motor is now engaged to extend and contract the machine  10  via the telescoping tongue assembly  25 . This aspect also allows for the removal of the tongue assembly  25  thereby greatly reducing the storage space requirements when the machine  10  is not I use. The tongue assembly  25  also has a hitch receptacle  28  and a steering device. The steering device features two dolly wheels  29  for minimal settlement in soft ground. The elongated tongue rail  26  also employs a steering shaft  30  with a tiller  31  that passes through it at the steering boss  32 . Two collars  33  are used to position the steering shaft  29  vertically.     C. The boom and cutting wheel assembly  35  has a two axis&#39;s  36   a ,  36   b  pivoting knuckle  36  at one end of the square tube boom  37 . The knuckle is pivoted from side to side by low lying tandem hydraulic cylinders  38 . At pivot pins  38   a  the boom is raised and lowered by a single longitudinally placed hydraulic cylinder  39 . This cylinder is placed between the upper knuckle  36  and the boom rail  37 . At the distal end of the boom is a shaft  49  mounted cutting wheel  40  with a plurality of cutting teeth  41  placed around its periphery. The cutting wheel  40  is driven by a hydraulic motor  42  by way of a belt or a chain drive  43  arrangement. A tensioning device  44  is also provided.      It would appear obvious to anyone of ordinary skill that it would be advantageous for the cutting wheel to be directly driven by the hydraulic motor. This concept has in the past been problem some due to power robbing binding that inevitably occurs from even the slightest misalignment between drive and driven components. Self-aligning couplings are commercially available but they require extensive spacing that is undesirable in this application      My alternative cutter wheel drive features a unique, compact, direct drive coupling that is capable smoothly transmitting power even while a slight miss-alignment condition exists      The cutting wheel shaft  49  is positioned by pillow block bearings  120  and  122 . The hydraulic motor  42  is positioned by motor mount  124 . These two entities are carefully positioned for the best possible alignment and then locked in place mechanically by bolts and welds as required. Any remaining minor miss-alignment is compensated for by my unique coupling.      This coupling feature a drive hub  130  attached to the motor  42  and a drive sleeve  132  attached to the drive shaft  49 . The immediary link is established by a plurality of drive pins  134 . A pronounced, generous clearance is provided between the drive hub  130  and drive shaft  132  as well as the drive pins  134  and their receptacles as drilled through hub  130  and shaft  132 . These clearances allow the drive pins  134  slight movements in rotation without the occurrence of power robbing binding or stress related failure. Diametric travel of the pins  134  is restricted by the motor shaft and the inner race of bearing  120 . Lubrication is admitted through grease fitting  136 . Over lubricating of the coupling is utilized to force remnants of wear causing dirt from its internal area. An o-ring, elatometric type seal is employed to retain grease and exclude dirt.      The overall result of this drive arrangement provides lower costs, reduced maintenance, and increased mechanical efficiency.      Essential to the machine  10  is the final element of the boom assembly. This is the grabber bracket  45  and attached manual actuating lever  46 . This member is pivoted to link the hydraulic force of the boom assembly  35  to the pivoting tractor axle assembly  55 . The grabber bracket is pivoted  47  on the boom and when not in use, is held tight to the boom by springs  48 . Hence, highly economical and reliable raising and lowering of the machine  10  is achieved.     D.  FIG. 4 , the pivoting tractor axle assembly  55  consists of a live axle  56  with two tractor wheels  57  and a hydraulic drive motor  58  and chain or belt drive  59 . It is obvious that some type of differential to optimize traction and cornering may be added to this assembly. These drive components share a common pivoting frame  60 . The frame is trussed for strength  61  and has bearings  62  for positioning the axle  56 .      This frame also has two other unique components. One is the grabber bar  63  for engagement with grabber bracket  45  to enable the raising and lowering of the tractor axle assembly  55  and thereby the machine  10 .      The-other unique component is comprised of the dog links  64 , connecting tie rod  65  and the dog link actuating lever  66 . These dog links are simultaneously maneuvered in and out of the lock down brackets  21  by the lever  66 . The dog links engage the brackets via fitted pins  67 . It is important to note, that while the machine is being towed from job to job, the grabber bracket  45  is pressured against the grabber bar while the tractor axle assembly  55  is locked in the up position. Thereby, the boom assembly  35  is held rigid and cannot sag to the ground.     E. The two, mirrored stub axle and tow wheel assemblies are telescopically mounted to main frame members  20  and are fixed in place by hitch pins  76 . These assemblies consist of square tube stub axles  77  with spindles  78 , hubs  79  and wheels  80 . They also carry fenders  81  with mounting brackets  82 . Note, these assemblies, like the tongue assemblies  25  may be removed to allow compact storage of the machine. In the work mode these wheels are just slightly off the ground but still act as out-riggers allowing a highly stable machine. They are intended to be removed only upon necessity. As previously mentioned, even upon removal the machine is more stable than prior art due to its lower center of gravity.     F.  FIG. 1 , the machine housing  90  is centrally located on the main frame  15  and securely mounted thereto. This housing, at present, utilizes a structural steel base  91  with an additional steel upper frame  92  supporting a sheet metal body  93 . It is obvious to anyone of ordinary skill that all or part of the frame may be eliminated by a more elaborate formation of the sheet metal body. Additional to the body there is a large, internal sheet metal angle to allow for the internal mounting of several hydraulic valves (not shown). Other components located within the machine housing  90  include the engine  94 , engine” controls  95 , fuel tank  96 , hydraulic pump  97 , with belt or chain drive  98 , oil reservoir  99  and the battery  100 . Also, within the machine housing are a considerable number of hydraulic hoses and their required fittings (not shown). Additionally, enclosed is an oil cooler  102  located adjacent to the cooling fan within the engine.      Protruding from the machine housing are the engine exhaust pipes  103 , cylinder controls  104 , cutting wheel control  106  and fuel tank filler spout  107 . This housing is easily accessible by two hinged sides or doors  108 . The top assembly  109  is very unique in that it not only protects the aforementioned components but provides ducted heat ventilation and a very useful tool tray also.     G. The ride-on platform  115  is a small, simple assembly mechanically fastened to the side main frame longitudinal rail  16 ; It consists of two L-shaped brackets  116  and a small, flat platform  117  suitable for one standing individual. This assembly greatly reduces deployment and withdrawal times. However, it is only optional due to safety and insurance considerations.     H.  FIG. 5 , the hydraulic system of this stump cutting device is also innovative and unique. It is powered by the engine  94  via a belt or chain drive  98  or the like driving a pump  97 . It is obvious that a manipulation of the various components in the machine housing would enable direct coupling of the engine  94  to the pump  97  but this is not preferred because of balancing and accessibility problems.      The hydraulic system is of accepted practice in that it utilizes a reservoir  99  and a pump  97 . A unique feature follows the pump that pressurizes the fluid. The fluid is routed through a priority flow control valve  101  that divides it into a low  102  and high  103  pressure circuit. The low pressure circuit is the priority circuit and it feeds the manipulating cylinders  38 ,  39 .      The result is smooth consistent movement of the cutting wheel via the boom. Lateral moving speed of boom is controlled by flow control valve  140 .      The secondary circuit  103  is utilized to drive either the cutting wheel motor  42  or the tractor wheels motor  58 . A basic flow selector valve  106  controls which hydraulic motor receives pressure. This arrangement permits a highly efficient drive system due to the elimination of unnecessary pressure loss. This system also provides very rapid stopping of the cutting wheel and the total elimination of accidental tractoring engagement during the cutting process. Also, an oil cooler is provided to maintain optimal fluid temperatures and allow the machine  10  to operate under the harshest of conditions.        
 
       OPERATION  
       [0056]     To maintain a clear presentation of the operation of this invention it is believed best to simply describe a single tree stump removal cycle. It is as follows: 
        1) The operator starts the engine  94  and while it warms-up, the trailer lights and hitch is disconnected allowing the dolly wheels  29  to be placed on the ground.     2) Using the conveniently located hydraulic controls the boom cylinder  39  lifts the boom assembly  35  to unlock the tractor axle assembly  55 . Note, at this time the grabber bracket  45  and grabber bar  63  are engaged with the tractor axle assembly locked in the up position to prevent accidental lowering and boom assembly  35  sagging while in tow. The boom is raised slightly to disengage the link pins  67 . The link pins are manipulated by the lever  66 . Once these are free the boom is lowered, thereby lowering the tractor axle assembly. When the tractor wheels are grounded the boom will slowly raise the tow wheel slightly off the ground. When the desired height is achieved, the boom is reversed and the link pins  67  are maneuvered into their up position dog slots. The grabber mechanism is now disengaged and as it is spring  48  loaded it will tuck tight against the bottom of the boom.     3) Hydraulic controls now engage the tractor motor  42  and, with dolly wheels  29  and steering tiller  31 , the machine is driven to the target tree stump. Should the machine be challenged by tight quarters, the stub axle and tow wheel assemblies are simply removed. It is at the discretion of the operator as to whether extra stability is required. Note: Irregular terrain has caused many roll-overs with previously accepted devices.     4) Upon reaching the stump, it is commuted by increasing power, engaging the cutting wheel  40  and using the knuckle  36 , boom  37  and cylinders to manipulate it as required. The tractor motor advances the cutter as necessary. When the cutting is completed the process is simply reversed, placing the device back upon the tow vehicle hitch.