US3362549A - Rear mounted log loader - Google Patents

Description

Jan. 9, 1968 J. M.l EWART REAR MOUNTED LOG LOADER 6 Sheets-Sheet 1 Filed June :3, 1966 FIG.

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Jan. 9, 1968 J. M EWART 3,362,549

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' REAR MOUNTED LOG LOADER Filed June 2, 1966 6 SheetfSheet 6 United States Patent REAR MOUNTED LOG LADER .lames Mervin Ewart, 525 Aldoraun Ave., Nanaimo, British Columbia, Canada Filed June 2, 1966, Ser. No. 554,725 Claims priority, application Canada, Mar. 8, 1966, 954,130 12 Claims. (Cl. 214-147) ABSTRACT F THE DISCLOSURE A log loading arrangement in which a boom and tong assembly is combined with a yarding spar tree o-n a mobile platform or carrier. The boom and tong a-ssembly, while being mounted -rotatably on the mobile carrier, is operatively suspended from the top of the spar tree.

This invention relates to logging and in particular to a combined yarding and log loading apparatus.

In accordance with presently known practice, devices for loading logs that have :been yarded consist of lifting cranes of the power shovel type that have been suitably adapted for logging work. An example of such a machine is shown in U.S. Patent No. 2,903,146 to Melay of Sept. 8, 1959. In such machines a lifting boom is raised or lowered by the well known gantry arrangement in which a line passes over a block or fairlead at the tip of the boom and is attached t-o a set of log gripping tongs. The operator actuates the mechanism so that the tongs grip the log substantially centrally but towards the rear or heel of the log. As lifting begins, the rear portion of the log is heeled against the bottom side of the b-oom to be held in this position while the machine rotates on its carrier to position the log over a truck and the tongs are then lowered and released.

A loading device according to the above description has numerous inherent disadvantages. For example, it requires 20,000 to 30,000 lbs. of counterweight to compensate for boom and load weight. -In addition to this, the boom, machinery deck, winch and house etc., constitute a substantial mass that c-an -be rotated only slowly.

The present invention overcomes the above disadvantages in providing a loader mounted in combination with a mobile spar tree such as that Ishown in U.S. Patent 3,015,471 of Jan. 2, 1962 and Canadian Patent No. 657,909 of Feb. 19, 1963. In this combination, a boom and jib arrangement is rotatably mounted to the mobile spar tree vehicle and is suspended from the t-op of the spar. As such, the loader is substantially lighter and less rigid than the boom of a conventional loader; the need for counterweights is eliminated due to the method of suspension; a greater range or reach is provided; and, in view of the low mass, speed of operation is substantially increased over known loaders.

`In the previously mentioned United States and Canadian patent-s, it has been described how a mobile spar tree provides many advantages over natural spars or those mounted on railway tracks. An embodiment of such a mobile spar is shown in FIGURE 1 of the accompanying drawings. Mobile spars have since shown their superiority in increased area clearing.

lt is, however, desirable to maintain the yard or log collecting area around the spa-r las clear as possible. This is not always the case due to the fact that it has normally been necessary to include in the yard one or more log loading machines to clear away the area of accumulating cuttings.

As will be seen from the drawings, the present invention provides Ilog loading means in combination with the 3,362,549 Patented Jan. 9, 1968 ICC spar thereby obviating the need for additional loading vehicles.

In accordance then to one aspect of the present invention there is provided, in combination with a spar tree mechanism, a rotatable log loader comprising a boom pivotally secured at one end Ito said spar tree mechanism; a jib secured for pivotal movement to the other end of said boom; a log gripping tong assembly pivotally mounted to the jib yat the end thereof remote from the boom; suspension lines interconnecting the upper end of said spar tree with the boom and tongs for support thereof; and means for rotating said boom, jib and tongs relative to the spar tree mechanism.

The above and other aspects of the invention will more readily :be understood from reference to the accompanying drawings illustrating the invention by way of example and in which;

FIGURE 1 is a schematic elevation view of the log loader mounted on and in combination with a mobile spar tree;

FIGURES 2 and 2a illustrate respectively two embodiments of suspending the boom and jib of the loader;

FIGURE 3 shows a further method of boom and jib suspension illustrating the tongs and the means for actuating boom and jib movement;

FIGURE 4 is a schematic illustration of the mechanism for rotating the boom assembly; and

FIGURES 5, 6 and 7 illustrate several means for maintaining a log in level orientation during lifting and transport.

Referring to FIGURE 1, a tracked carrier illustrated generally at 10 supports a collapsible spar tree 12 mounted on the car-rier 10 -by suitable support 14 and secured in position by guylines 16 and 1S in accordance with the patents mentioned. The carrier includes a yarder 20 to actuate sheaves 22, 24 and their respective lines 26, 28 in order to collect cut logs (not shown) to the immediate area.

In `accordance with FIGURES 1, 2, 2a, and 3, a log loading arrangement indicated generally at 30 is mounted on a turntable 32 rotatably secured to the rear of the carrier 10 that is given additional support at 34, the loading arrangement 30 consisting basically of a :boom 36, jib 33 and tong assembly d0. Preferably, the boom 36 is of box-like construction and the inner end thereof is pivotally mounted to the turntable 32, for example between flanges 42 by a pivot pin 44. The jib 36 has a pivotal mounting at both of its ends. Its inner end 46 (that nearest the carrier 10) is secured for swinging movement at 48 on, and relative to, the outer end of the boom 36 while the outer or remote end S0 ofthe jib is similarly secured to the tong assembly 40. The latter includes self closing tongs 52 and log levelling means in the form of a heeler 54.

As shown in FIGURE 2, the boom arrangement 30 is raised or lowered relative to the turntable 32 by suspension lines. A lfirst line 56 is connected at one end to the tong assembly 40 and terminates at its other end in a pulley block 58. A second line 60 is utilized to raise the other end of the boom 35 and this line may be arranged in three embodiments. In FIGURE 2, line 60 is secured at one end to the cute-r end of boom 36 adjacent its connection to jib 3S. The line then is played around a 'lirst upper pulley 62; downwardly and around pulley 58; then back up overa second yupper pulley 64 and thence to a boom hoist unit 66 located on the carrier 10 adjacent the turntable 32. It will be noted from FIGURE 2 that upper pulleys 62 and 64 are mounted in a common block 68 connected to a swivel mounting 70 atop the spar tree 12.

In the embodiment of FIGURE 2a, line 60 is secured at its free end 61 to the pulley 5S and is then played about pulley 62, back downwardly around pull-ey 58 and thence around upper pulley 64 and down to hoist unit 66.

ln the FIGURE 3 embodiment, the rst line 56 is also connected at one end to the tong assembly 40 and is also provided on its free end with the pulley block S5. However, swivel mounting 70 retains only one upper pulley 62a and its associated block 68 has a free end of the line 60 secured thereto. Line 60 then proceeds from block 68; around lower pulley S; around upper pulley 62a to a boom pulley 72 and thence to the hoist unit 66 which, in this embodiment, is mounted within the confines of the structure of boom 36. It will be noted that the unit 66 includes a driven suspension line drum 74 actuated for example by a pair of hydraulic motors 76. From either embodiment it will be evident that a drawing-in or lettingout of line 60 by the hoist unit 66 will raise or lower, respectively, the whole boom arrangement 30.

Hydraulic means for swingint7 the boom system 30 in an arc from its carrier position throughout a substantial area of the yard is indicated generally at 78 in FlGURE 3 and is .shown in a schematic circuit in FIGURE 4 of the drawinns. A turntable such as 32 in the present device may be powered in various ways such as by a hydraulic motor but when torque requirements are very high and the rate of swing is slow (both of which apply to the environment of the present invention), high speed hydraulic motors coupled with .speed reducers become extremely costly. A rack and pinion arrangement powered by slow moving cylinders is a further method of turntable rotation but substantial room must be provided for the racks to extend at the end of piston travel. A cable and sheave arrangement constitutes a third method but an inherent disadvantage is the stretching of the cable which then becomes loose on the drum.

The turntable rotating device 78 of FIGURE 4 utilizes a chain and sprocket arrangement including means to prevent chain jumping.

Turntable 32 is axially connected to a sprocket 70 about which is circulated a drive chain 72 having little appreciable stretch. Each end of chain 72 is respectively connected to the free ends of piston rods 74a and 74h extending rom cylinders 76a and 76h that serve to enclose pistons 78a and '73b as shown. Each cylinder includes a rod end 30 and a blind end 82. The rod ends are interconnected by a fluid line 84 incorporating a pump 36 and relief valve 88. The blind ends of cylinders 76a and 76b are connected by lines 90 to a manual control valve 92 provided with an adjacent pump 94. Lines 90 include relief valves 96, 98 and restrictors 100.

With valve 92 in a neutral position, there is Zero pressure on the blind ends 82 of the cylinders, full pressure, say in the region of 2000 to 2500 psi., being maintained on the rod ends 00 by pump 36 and regulated by relief Valve 88. in this neutral position the rotating system is balanced and no revolving of the turntable 32 takes place, although full tension is maintained on the chain 72. By

ianually actuating control valve 92 either one way or the other, pressure from pump 94 is introduced via lines 90 into the blind end 82 of one of the cylinders, say for example 76b. This upsets the balanced condition by transferring pressure on the rod end 80 of cylinder 7Gb to the rod end of cylinder 76a to thereby rotate the sprocket 70, turntable 32 and the associated boom arrangement 30. Relief valves 96 and 98 protect the cylinders from over pressure and the restrictors 100 absorb Huid leakage past the pistons 73a and 73!) and returns the tluid to a reservoir (not shown).

rhe effective reach of the loader 30 (notwithstanding boom and jib length) is controlled both by raising and lowering the outer end of boom 36 by suspension line 60 and through actuation of the hydraulic jib cylinder 102, shown in FIGURE 3, that is connected at one end to the boom 36 and at the other end to the jib 33 adjacent its upper end, i.e. that end close to the jib-boom connection.

It Will be appreciated that known methods of holding a log in a tong assembly and heeling it against the underside of the boom are quite unsatisfactory, making levelling of the log very difficult during loading operations. It also limits the extent to which the log may be tilted. FIGURES 5, 6 and 7 of the drawings illustrate three methods of log tilt control developed to increase the range of log tilt, obviate the necessity of boom-heeling a log prior to lifting it; and whereby the log may automatically be maintained in level or substantially level orientation during picking-up and loading thereof.

As shown in FGURE 3, a hydraulic cylinder 104 iS mounted between the jib 38 and to toothed heeler 54 of the tong assembly 40. Actuation of this cylinder 104 governs the amount of ypivotal movement between the tong assembly 40 and jib 3S and thus the angle of tilt on the log L as well.

Referring now to FlGURE 5 there is shown an actuating control for cylinder 104 effected either automatically through a control valve 106 and pendulum valve 108 or manually through valve 110, this choice being dependent on the position of a switch valve 112. Pump 114 is associated with valves 106 and 110 while pump 116 and relief valve 118 are associated with the pendulum valve 108.

It is evident from FIGURE 5 that when switch valve 112 is positioned for automatic control, manual valve 110 is by-passed in the circuitry and control passed to valve 106. Pendulum valve 108 detects hydraulically the amount of tilt on the log and it sends a pilot signal to actuate valve 106 to retract or extend cylinder 104 according to the reach of the boom 36 being effected by cylinder 102 thereby to maintain the log substantially horizontal. it will be noted that the pendulum 10861 is disposed in a tluid such as oil 109 to dampen its action and to reduce hunting or erratic action.

A second embodiment for log levelling is shown in FIGURE 6. Here again, cylinder 104 is connected between the jib 38 and heeler 54 and may be manually actuated by control valve through lines 117 and manual switch valve 119. For automatic level control, iiuid is controlled by a cam actuated valve 120, the cam 122 rotating in response to boom reach. Tong assembly i0 is provided with a sprocket 124 as is the inner end of the boom 36 with a sprocket 126, to which the cam 122 is mounted. At the junction between the jib 38 and boom 36 two sprockets 128 and 130 are axially connected. A rst chain 132 interconnects sprockets 124 and 128 while chain 134 interconnects sprockets 126 and 130.

As the boom 36 is extended or retracted in reach by cylinder 102, the chain transmission `will rotate cam 122 to actuate valve to effect levelling of the log through automatic manipulation of cylinder 104.

Turning now to FGURE 7, a still further method of log tilt control comprises three sheaves 133, 135 and 137 all of equal diameter mounted at the connections of boom-to-turntabie; boom-to-jib; and jib-to-tongs, respectively with sheave 137 being welded to the tong assembly A cable 138 is secured at one end to tong 40 and is passed over the remaining sheaves 135 and 133 and is a parallelogram action which ensures a constant angle of log tilt during movement of the boom 36 and jib 38. However, this angle may be' varied by means of a cylinder 140, placed intermediate the cable ends and actuated by a valve 142 via lines 144. Once the log angle is set, whether the log be horizontal or tilted, it will not change regardless of boom and jib movement.

I claim:

1. In combination with a mobile carrier; a spar tree mounted on the carrier; a rotatable log loader suspended from the top of said spar tree and mounted on said carrier, said loader including; rotation means 0n the carrier; a boom pivotally secured at one end of said rotation means, a jib secured for pivotal movement to provided with a weight 139 at its inner free end to create* the other end of said boom, a log gripping tong assembly mounted to said jib remote from said boom; swivel means mounted for rotation atop the spar tree; suspension lines interconnecting the upper end of said spar swivel means and the tree with said boom and tongs for pivotal and rotational support thereof; and means for rotating said boom, jib and tongs relative to said spar tree and its carrier.

2. In combination with a mobile carrier mounting a spar tree, a rotatable log loader suspended .from the top of said spar tree and including, a turntable rotatably mounted on said carrier adjacent the base of said spar tree; a boom pivotally secured at one end to said turntable; a jib secured for pivotal movement to the other end of said boom; means for extending said jib relative to the boom; a log gripping tong assembly pivotally mounted to said jib remote from said boom; swivel means mounted for rotation atop said spar tree; suspension lines interconnecting the swivel means and the upper end of said spar tree with said boom ad tongs for pivotal and rotational support thereof; and means for rotating said boom; jib and tongs relative to said spar tree and carrier.

3. A log loader according to claim 1 including a hoist unit on said carrier adapted to actuate said suspension lines for vertical movement of said boom, jib and tong assembly relative to said carrier.

4. A log loader according to claim 2 wherein said jib extending means comprises a hydraulic cylinder connected at one end to said jib and at the other end to said boom.

5. A log loader according to claim 1 wherein said boom, jib and tong rotating means comprises a turntable rotatably mounted on said carrier adjacent the base of said spar tree; a sprocket axially connected with said turntable; a pair of hydraulic balanced cylinders including pistons and rods extending therefrom; transmission means interconnecting said sprocket with the terminal ends of said piston rods; pump means for maintaining pressure on either end of said pistons; and a control valve for transferring said pressure from one cylinder to the other to effect rotation of said sprocket and to maintain tension in said transmission means.

6. In combination with a mobile carrier; spar tree mounted on the carrier a rotatable log loader suspended from the top of the spar tree and including a boom pivotally secured at one end to said spar tree carrier; a jib secured for pivotal movement to the other end of said boom; a hydraulic cylinder interconnecting said jib and boom for extending the reach of the jib; a log gripping tong assembly pivotally mounted to said jib remote from said boom; swivel means mounted for rotation atop the spar tree; suspension lines interconecting the swivel means and the upper end of said spar tree with said boom and tongs for pivotal and rotational support thereof and to eifect vertical movement of said boom relative to the carrier; means for rotating said boom, jib and tongs relative to said spar tree comprising a turntable rotatably mounted on said carrier; a sprocket axially connected to said turntable; a pair of pressure balanced hydraulic cylinders adapted, when actuated, to extend and retract with respect to one another; tensioned transmission means interconnecting said cylinders to the sprocket whereby extension and retraction of said cylinders effects rotation of said sprocket, turntable and boom; and means for selectively and automatically adjusting the orientation of the tong assembly with respect to said jib for levelling a load carried by said tong assembly.

7. A log loader according to claim 6 wherein said hydraulic cylinders include pistons and rods projecting therefrom, the transmission means comprising a chain engaging the sprocket with each end of said chain being connected to an associated piston rod and a control valve for maintaining said chain under tension during rotation of the sprocket.

8. A log loader according to claim 6 wherein the tong adjusting means comprises a hydraulic cylinder interconnecting said jib and tong assembly; a manual control valve connected to said cylinder by uid lines for selectively extending or retracting the tong assembly relative to the jib; and a pendulum valve also connected to said cylinder by fluid lines to automatically adjust and extension or retraction in response to boom reach and the angle of the tong assembly set thereby.

9. A log loader according to claim 6 wherein the tong adjusting means comprises a hydraulic cylinder interconnecting the jib and tong assembly; a manual control valve connected to said cylinder by fluid lines for selectively extending or retracting the tong assembly relative to the jib; a first sprocket connected to the tong assembly; a second sprocket mounted on the inner end of said boom and a pair of further sprockets axially connected together at the pivotal junction between said boom and jib; transmission means interconnecting the first sprocket with a sprocket of said further pair and also between the second sprocket and the remaining sprocket of said further pair; an automatic control valve interconnected to said cylinder through said uid lines; and a cam secured to said second sprocket on the boom adapted, when the reach of said boom is adjusted, to actuate said automatic control valve to effect extension or retraction of said cylinder in response to the reach of the boom.

10. A log loader according to claim 6 wherein the tong adjusting means comprises a irst sheave rigidly secured to the tong assembly; a second sheave co-axially secured. intermediate the boom and jib, to the pivotal connection therebetween; and a third sheave co-axially mounted with the pivotal connection of the boom to said turntable; a cable secured a one end to the irst sheave and extending over said second and third sheaves; all of said sheaves being of identical diameter whereby adjustment of the reach of the boom effects a corresponding adjustment in the angle of said tong assembly with respect to the jib; and means for selectively altering the length of said cable.

11. A log loader according to claim 8 including a switch valve for transferring actuation of said cylinder from manual to automatic control.

12. A log loader according to claim 10 wherein the selective adjusting means comprises a hydraulic cylinder intermediate the ends of said cable; a pump for supplying fluid to said cylinder through uid lines; and a valve for directing said fluid.

References Cited UNITED STATES PATENTS 3,120,310 2/ 1964 Roberts et al 214--147 3,204,795 9/ 1965 Larson 214--147 GERALD M. FORLENZA, Primary Examiner.

HUGO O. SCHULZ, Examiner.

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