Abstract:
A post driver has a combination of hydraulically operable orthogonal and angular mechanical carriages giving five degrees of motion of the driving hammer for the setting of posts in various soils and terrain slopes. Adjustment of the carriages allows accurate location of posts in a fence line that is offset from the line of travel of the supporting tractor. The structure of the apparatus provides distributed weight to both sides of the tractor to assure its stability and safety for operations over variable terrain slopes. A post sleeve and holding bar contain the posts for hands-off driving and also provide means for overcoming post misalignment due to variable density and stony soils. A damping device is added to the impact hammer mechanisms.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to mobile machinery for driving posts into the ground for the construction of fences, safety barriers, guard railing, retaining walls, or like constructions. It is intended as a substitute for hole digging, fill, and tamping apparatus. 
     2. Related Prior Art 
     For many decades the customary approach to the building of fences involved the digging of holes of appropriate depth, the placement of the post therein, and filling of the surrounding hole with removed soil and tamping to stabilize the emplaced post, all of which required much manual labor. Then came angle and &#34;Tee&#34; metal posts, or small cross section, that could be driven in place by hammer or manual driving tools. But posts, having large cross sections are still desired for many decorative and utilitarian applications, including fences about lawns and pastures for horses, and for safety barriers, etc. A long standing need has existed for efficient labor saving apparatus for setting posts upright in all types of soils and upon terrain having variable slopes and contours. 
     An early mobile post driver is disclosed in U.S. Pat. No. 2,940,267, issued to Shaver in 1960. Shaver teaches a percussion driver, that is, a hydraulic system to lift a mechanical mass of a driving block and H beam above the post so that upon release of hydraulic pressure gravity will provide a driving force to set the post in the soil without the need for digging or filling post holes. The device of Shaver is intended for mounting on the longitudinal axis of a tractor of the row crop type generally used in agricultural operations. Mechanical adjustments were provided for vertical driving of the post, however the location of the post at a desired place required accurate maneuvering of the tractor. 
     In a less demanding allied area, the U.S. Pat. No. 3,563,319, issued to Nixon in 1971 teaches apparatus for the setting of small pins or stakes in concrete forms used in highway construction. Since the concrete form must follow the slope of the graded roadbed the only need for verticality adjustment is in the lateral direction to the roadway. The setting of pins is accomplished by hydraulic force rather than by gravity action on hammer mass. Verticality of the applied force is adjusted by a hydraulic lateral tilting of the chassis of the platform which is supported by three wheels, two of which are arranged longitudinally and the third being offset laterally from the two. 
     SUMMARY OF THE INVENTION 
     This invention provides improvements in apparatus for driving posts in various soils and terrain slopes. The most frequent application is in the construction of fences along a specified line or boundary. Although the invention is not limited in its embodiment, typical posts for fencing range 7-9 feet in length and as large as 8 inches by 10 inches in cross section. 
     The system of this invention requires a heavy duty tractor of the type having a wide front axle to provide a stable mobile platform for the post driver so that operations may be safely performed on steep terrain slopes. A massive belly mounted frame, attached to the undercarriage of the tractor supports the post driving mechanisms at a variable offset position on the right side, facing forward, of the tractor. The belly mounted frame extends beneath the tractor frame and beyond to the left side for the support of static weights and a sump reservoir supply of hydraulic oils. The mass of the hydraulic oil and weights on the side of the tractor opposite to the driving mechanism is for stabilizing the tractor against roll reactions about its longitudinal axis during the operation of the drive mechanism. Additional weights are mounted at the front of the tractor and each wheel is filled with liquid for weight to suppress vibrations and bounce about the tractor roll and pitch axes. 
     The belly frame includes a hydraulically operable carriage having a forward-aft travel of sixteen (16) inches and a lateral travel (in-out) perpendicular to the longitudinal axis of the tractor of two (2) feet. Thus each post may be accurately placed in a fence line without extensive tedious maneuvering of the mobile tractor. But in order that posts may be driven vertically on compound slopes of the terrain, the movable carriage has superimposed hydraulic tilting mechanisms in two directions. The driver may be tilted forward or backward 35 degrees about an axis perpendicular to the longitudinal plane of the tractor. The driver may simultaneously tilt in or out 35 degree about an offset axis parallel to the tractor&#39;s longitudinal plane. All of the control valves for operation are located at the post driver for the convenience of the attendant. 
     Therefore it is a principal object of this invention to provide apparatus for driving posts at the expense of minimum manual labor. 
     Another object of this invention is to provide a mobile platform for post driver that may operate from an offset line of travel to set posts in a prescribed fence or boundary line; or adjacent to otherwise hazardous locations. 
     Another object of this invention is to provide a flexible and versatile carriage and tilting controls for the post driver to enable accurate location and verticality of each post independent of variable terrain slopes and precise positioning of the mobile tractor platform. 
     Another object of this invention is to provide an adequate distribution of weight to improve the stability of the tractor platform as posts are driven by impact forces. 
     Another object of this invention is to provide apparatus and accessory tools for aligning rectangular posts with the desired fence line for proper attachment of fencing boards or rails. 
     Another object of this invention is to provide apparatus and accessory tools for resisting the misalignment of posts being driven into stony or variable density soils. 
     Another object of this invention is to use the weight of the operating reservoir of hydraulic fluid for balancing the mass distribution of the system. 
     Another object of this invention is to provide a mechanical sleeve for holding a post throughout the driving procedure so that the attendant may stand clear of the moving elements and so that vertical alignment of the post may be forced by carriage movement while the driver hammer freely operates. 
     Another object of this invention is to provide a side mounted post driver supported by a belly frame that may be readily assembled or dismounted from the tractor frame. 
     Another object of this invention is to locate the complete system center of gravity at a low elevation point near to the geometric center of the platform. 
     Another object of this invention is to increase the performance capability of the platform by the addition of an auxiliary hydraulic system powered by the tractor engine and cooled by the tractor cooling fan. 
     Still another object of this invention is to provide means of stowing the post driver mechanisms during transport of the apparatus. 
     Still another object of this invention is to locate all post driver controls for standing operation by the attendant at a position convenient for insertion of posts to the driver. 
     Other objects, features, and advantages will become apparent from the description in connection with the accompanying drawings of the preferred embodiment of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is described with reference to accompanying drawings, in which: 
     FIG. 1 is an elevation view along the longitudinal axis looking to the rearward from the front of the tractor. 
     FIG. 2 is a plan view of the system. 
     FIG. 3 is an elevation side view showing the post driver portion mounted to the tractor. 
     FIG. 4 is an elevation side view showing the static counterweights and hydraulic reservoir portions of the system as mounted to the tractor. 
     FIG. 5 is a perspective of the hydraulic actuated carriage and tilt mechanisms. 
     FIG. 6 is a view of the attendant&#39;s controls. 
     FIG. 7 is a frontal perspective of the belly frame. 
     FIG. 8 is a driver side view of the belly frame. 
     FIG. 9 is a side view of the in-and-out orthogonal carriage. 
     FIG. 10 is an end view of the in-and-out orthogonal carriage. 
     FIG. 11 is a side view of the fore-and-aft slide tube. 
     FIG. 12 is an end view of the fore-and-aft slide tube. 
     FIG. 13 is a view of the post driver sleeve. 
     FIG. 14 is a cross section through the driver assembly along lines A--A of FIG. 13. 
     FIG. 15 is a block diagram of the hydraulic subsystems. 
     FIG. 16 is a plan view of a post aligning tool. 
     FIG. 17 is a view of a damper for the post driver springs. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the drawings there is shown a heavy duty tractor 20 of the four wheel wide front axle type. The post driving subsystem 21 is offset mounted to the right side of the tractor 20, FIGS. 1-3, through a belly subframe 22, FIGS. 7-8, that extends to the left side of the tractor 20 to support static counterweights 23 and a reservoir 24 containing a supply of operating fluid for the post driving hydraulic subsystems. The tires of each of the four tractor wheels are filled with a non-freezing liquid for added weight thus the total mass provides a low center of gravity and stability during operation of the mechanisms on terrain of varying slopes. 
     The post driving subassembly includes a tower 25, extending upward from the angular carriage 28 through a pivoting channel mount 30 or fixture that is hydraulically operable to achieve vertical erection of the tower on terrain slopes through a lateral tilt cylinder 31 and a parallel tilt cylinder 32. The tilt cylinder 32. The lateral and parallel tilt cylinders, 31 and 32, are double acting and have a range of plus and minus thirty five degrees of angular movement. A vertical lift cylinder 33, one end being attached to the tower 25 raises a drop hammer H-channel 26, above a post being driven, against the restraining force of a pair of return coiled driving springs 34. The vertical lift cylinder 33 is single acting. Upon release of hydraulic pressure in the lift cylinder 33 the combined forces of gravity and of the return driving springs produce rapid downward movement of the drop hammer 26 with impact to drive a post into soils or grounds of varied density or hardness. Interposed between the pivoting mount 30 and the tower 25 is the post sleeve 27 which wraps around the H-channel of the drop hammer 26, with clearance for movement within. The post sleeve 27 provides a recessed rectangular guide cavity 35 into which the post is placed in anticipation of driving it into the soil. The post sleeve 27 is provided with a pair of retaining rings 36, welded to opposite sides of its frontal surfaces so that a holding bar 37 may be passed through each ring to bridge the guide cavity 35 to capture a post placed therein while the drop hammer 26 is operated to drive posts. A pad 38 of rubber or similar material, FIG. 17, is positioned within the tower 25 in contact with the return driving springs 34 for suppressing spring oscillations and failures due to hammer impact. 
     Attached to the side of the post sleeve 27 facing to the rear of the tractor 20 is the attendant&#39;s station for the post driver subsystem 21. A top bracket 39, attached to the sleeve 27, has assembled thereon a first double acting valve 40 for fore-and-aft carriage control and a second double acting valve 41 for in-and-outward carriage control. Attached lower down to the sleeve 27, the low bracket 42 has assembled thereon a single acting valve 43 to control the lift of the drop hammer 26, plus a third double acting valve 44 for control of lateral tilt and a fourth double acting valve 45 for control of parallel tilt. 
     Between the belly subframe 22 and the post driving subsystem 21 is the orthogonal carriage 29 which provides positioning of posts in rectangular coordinates offset from the longitudinal axis of the tractor 20, perpendicular and parallel thereto. The belly subframe, FIGS. 7, 8, provides two parallel five inch rectangular slide tubes 46, five feet in length which are suspended perpendicular to the tractor 20 frame by four mounting plates 47. Opposite the carriage 29, the ends of the slide tubes 46 are terminated and bridged by the counterweight 20 and reservoir 24 subassembly 48. The reference end of the double acting in-out hydraulic cylinder 49, which lies symmetrically between the slide tubes 46, is attached to the counterweight and reservoir subassembly 48. The upper and lower surfaces of each of the parallel slide tubes 46 function as slide ways for movement in and out of the lateral orthogonal subcarriage 50. 
     The in-out subcarriage 50, FIGS. 9, 10 has two parallel slide channels 51, formed from three inch angle stock, that are positioned in the subcarriage 50 for mating with, enclosing, and sliding upon the rectangular slide tubes 46 of the belly subframe 22. The inner surfaces of each top and each bottom flanges of the parallel slide channels 51 provide slide ways for movement upon the enclosed rectangular tubes 46 of the belly subframe 22, FIGS. 8 and 10. A cross member with Clevis bracket 52 receives the yoke of the piston of the in-out hydraulic cylinder 49. The range of the in-out movement provided by the subcarriage 50 and hydraulic actuator 49 is two feet. Reinforcing cross members 52 maintain the integrity of the in-out subcarriage 50. Welded to the outer extreme end of the slide channels 51 and perpendicular thereto, are two parallel fore-and-aft guides 53 that are separated to receive within the guides 53 a single ten inch fore-and-aft rectangular slide tube 54 which has symmetrically welded to each vertical side thereof a half by one inch rectangular slide track 55 extending the length of the slide tube 54, FIGS. 11 and 12. Each of the fore-and-aft guides 53 is provided with a slot 56, or groove, extending the length thereof for receiving and enclosing the respective slide track 55 of the fore-and-aft slide tube 54. 
     The ends of the two guides 53 facing to the rear of the tractor 20 are bridged and terminated by a heavy reinforced guide cross member with pivot yoke 57 which receives the reference end of a fore-and-aft hydraulic actuator 58 which is centered horizontally and slopes upward diagonally within the slide tube 54 for connection to its upper pivot 69. The limit of fore-and-aft movement produced by the actuator 58 is sixteen (16) inches. The fore-and-aft guides 53 are further reinforced by an assembly of underside cross and longitudinal angle members 59. A footstep 60 is welded to the outer guide in near proximity to its rearward end. 
     Superimposed upon the upper surface of the fore-and-aft slide tube 54 is the angular carriage 28. An intermediate mounting fixture or base plate 61, spaced apart but bolted to the fore-and-aft slide tube 54, has a bent downward flange on the side adjacent to the post driving subsystem 21 and a bent upward flange on the side toward the tractor 20 for reinforcement of the plate 61. Centered and welded to the base plate 61 are an axle tube and mount blocks 62 for the transverse pivot axle 63 which allows a fore-and-aft or parallel angular tilt of the post driving subsystem 21 relative to the tractor&#39;s longitudinal axis. The reference or cylinder end of the double acting hydraulic pivot actuator 64 is tied to the base plate 61 through a vertical clevis bracket 65 that is welded at the forward edge of the base plate 61. The yoke of the piston end of the actuator 64 operates through a crank arm 66 for tilting the post driving subsystem 21 about the pivot axle 63. The rotatable pivot axle 63 has, at its inner end nearest the tractor 20, brackets welded to it forming a lateral yoke 66 in which the cylinder end of the double acting lateral tilting hydraulic actuator 67 is pinned. The lateral tilting actuator extends upward in a plane perpendicular and to the tractor 20 to connect in an upper pivot joint 68 of the drive subassembly pivoting mounting fixture or channel 30. The outward end of the pivot axle 63 connects in a lower pivot joint 70 of the mounting channel 30. 
     In the complete assembly the mounting channel 30 abuts the rearward side of the post sleeve 27 which encloses the tower 25 and the drop hammer elements of the post driving subsystem 21. The channel 30, the sleeve 27 and the tower are bolted together and are thus, as a combined mechanism, responsive to hydraulic actuator control to four degrees of mechanical motion relative to the tractor 20, i.e. fore-and-aft and in-and-out orthogonal movement plus parallel and lateral angular tilting movement. 
     A schematic or flow diagram for the hydraulics of the post driver, FIG. 15, shows a dual hydraulic subsystem utilizing a low volume hydraulic pump of the tractor 20 and an added high volume auxiliary external source. The engine 70 of the tractor 20 is the prime source of power for motion and for hydraulic pressure and volume. The engine 70 is coupled to the power train gear box 71 having internal transmission gearing 71, a sump reservoir 73 for lubricating and hydraulic fluid, the tractor hydraulic pump 74. The hydraulic output of the tractor pump 74 is transmitted to a relief or bypass valve 75 which is in turn connected to each of the fore-and-aft 40 and in-and-out 41 control valves which operate the double acting fore-and-aft 58 and in-and-out 49 actuators of the orthogonal carriage 29. The bypass valve 75 returns the excess hydraulic fluid to the sump 73 of the power train gear box 71. 
     The high volume auxiliary hydraulic source operates from the separate reservoir 24 mounted externally on the belly subframe 22. The front crankshaft of the tractor engine 70 is . coupled to the cooling fan 77 and to an added auxiliary high capacity hydraulic pump 78. As the engine crankshaft rotates the auxiliary pump 78 draws hydraulic fluid from the reservoir 24 through dual filters 79 and an added hydraulic fluid cooling radiator 80 and supplies fluid under pressure via hoses through a a system dumping valve 81 to the parallel combination of a relief valve 76 and the control valves 43, 44, and 45 for the drop hammer vertical lift actuator 33, the lateral tilt actuator 31, and the parallel tilt actuator 32 respectively. The lift actuator 33 is single acting, the tilt actuators, 31, and 32, are double acting. The excess fluid under pressure is returned via hoses by the external relief valve 76 and control valves 43-45 to the reservoir 24. The auxiliary source supplies the high volume needs of the post drop hammer lift actuator 33 and the needs of the angular carriage 28. The attendant may switch the system valve 81 to a dumping mode when the post driver is not to be used while the tractor is operating. 
     In post setting operations the tractor 20 is advanced by the attendant along but offset from the fence line to the approximate location for the next post. The orthogonal and angular carriages 29 and 28 are operated as necessary to accurately locate and vertically align the tower 25 and drop hammer 26 for the particular post location in tractor position, and terrain slope. As the post is being driven into the ground should the presence of stones, etc. deflect the post from the vertical, operation of the angular and orthogonal carriages 28, 29 may be used by the attendant to restore by force applied through the post sleeve 27, the verticality and/or location of the post. In some instances a rectangular post being driven against stones or non-uniform soils may be rotated about the vertical axis relative to a fence line. The tool 82, shown in FIG. 16 is used by the attendant to realign the post in azimuth angle as driving is continued. The tool 82 is adaptable by inserts 83 for various sizes of posts. 
     This invention may be embodied in other specific forms without deviating from its concepts and essential characteristics. The preferred embodiment disclosed above is therefore to be considered in all respects as illustrative and not limiting, the scope of the invention being indicated by the appended claims.