US2145352A - Well drilling apparatus - Google Patents

Description

2 5 M, 5 As 1 29 G. HEINISH Jim. QM, E939.

WELL DRILLING APPARATUS Filed June 19 5 Sheets-Sheet l I N VE N TC) R Gi o/Pg: Ai /Ms Jana 31, W39 G. HEINISH WELL DRILLING APPARATUS Filed June 19, 1936 5 Sheets-5heet 2 ATTORNEY Em, 3T1 m (5. HEINISH 293453352 WELL DRILLING APPARATUS Filed June 19, 1936 5 SheetsSheec 3 INVENTOR ATTORNEY Jam. 31,. W39. 6. HEINISH WELL DRILLING APPARATUS 5 Sheets-Sheet 4 Filed June 19, 1936 Ba m w ww m VEN to R 4 Ai /[wad ATTORNEY "G. HEINESH WELL DRILLI NG APPARATUS Filed June 19, 1956 5 Sheeis-Sheec 5 QNVENTOR 6 ATTORNEY Patented Jan. 31, 1939 UNITED STATES PATENT OFFICE WELL DRILLING APPARATUS poration of Ohio Application June 19, 1936, Serial No, 86,115

11 Claims.

This invention relates to improvements in well drilling apparatus and more particularly to apparatus of the all-steel type.

In apparatus of this type the drilling tools are raised and lowered by the action of a spudder which is operated by a power unit from which energy is derived to assist the force of gravity in delivering a sharp blow with each down stroke of the tools. All of the energy developed is not exii) pended at the bottom of the hole being drilled, in fact, in some formations a considerable portion thereof travels back up the drill line to be either redistributed or dissipated through the apparatus at every point where the drill cable is in contact with the apparatus, usually resulting in high line tension and stressing of the parts of the apparatus. Particularly is this true when a steel drill cable is used because there is little inherent resiliency in such cable. Hence, it is desirable to reduce this line tension and shock to the parts as much as possible and it is an object of this invention to provide a novel shock absorbing and energy storing means for this purpose. Another object is to locate this means on the drill whereby it will function efficiently, for example, in the spudder, not only to absorb the shock of the drop stroke, but to reduce the drilling line peak tension, to neutralize the shock of the tool pickup, to assist in conserving unused tool energy and to assist in reducing the power requirements of the apparatus.

Also, in prior apparatus of this type the drilling motion depended on a speed variation of the power unit to get a quick drop and a long pick up. The operator would set the carburetor throttle in an open position so that the engine would deliver an average power, no means being provided to vary the power delivered in accordance with the power demand. As a result the engine speed decreased when the load came on during the pickup stroke and increased during the drop stroke, thereby obtaining a quick drop and a long pickup. Since the pitman connections were placed practically over the center of the crankshaft whereby a substantially equal pickup and drop stroke was obtainable, it was necessary to operate the engine as aforesaid to obtain a drilling motion, and a change in the load caused a proportional change in the drilling motion. Since such apparatus was built for average conditions it was not suitable for all conditions. It obviously is more desirable to have apparatus wherein the drilling motion will be suited to all conditions and it is a further object of this invention to provide such apparatus wherein the drilling motion is novel in that the engine, countershait and crankshaft are run at substantially a constant speed by means of a novel governor control, assisted by power stored up in a flywheel and in the shock absorbing means.

Furthermore, in prior apparatus it was usually necessary to race the engine to start drilling and to slip the clutch and open the throttle quickly as the load came on in order to prevent stalling. Also, it was necessary to close the throttle quickly when drilling was stopped to prevent engine racing. It is a further object of the invention to provide a governor which will open and close the engine throttle whereby the power delivered by the engine will be varied to meet the power demand, thereby eliminating any tendency of the engine to race or stall.

An additional object is to provide for more effective power application and distribution in a drill of this type than has been possible heretofore.

Other objects and advantages will become apparent from the following description taken in conjunction with the accompanying drawings.

In the drawings,

Figure 1 is a side elevation of my drilling apparatus with parts broken away and shown in section;

Figure 2 is a plan view of same with the mast shown in section;

Figure 3 is an enlarged view of the countershaft and adjacent parts, being taken substantially on line 3-3 of Figure 1;

Figure 4 is an enlarged plan view of one of the spudder arms;

, Figure 5 is a. section taken substantially on line 5--5 of Figure 4;

Figure 6 is an enlarged detail view of the carburetor throttle control; and

Figure '7 is a diagrammatic view illustrating the variable leverage principle of my shock absorber.

Referring to the drawings, the base of the apparatus is formed with longitudinal side frame members Ill and H which preferably are I-beams and which are connected at their front ends with a transverse I-beam l2, while their rear ends are connected with a transverse channel beam l3. Intermediate their ends the beams I0 and H are connected by spaced transverse I-beams I l and i5, which latter beams are connected by relatively short longitudinal I-beams l6 and H. Beneath the base, additional transverse members it may be secured to facilitate mounting the apparatus on wheels or on the chassis of a truck.

Extending upwardly from the side frame memhers I 0 and H are four vertical channel beams l8, forming respectively the four corner members of a superstructure which is braced on each side by diagonal channel beams l9 and 20. Suitable braces (not shown) for the front and rear of the superstructure may also be provided. As shown in Figure 1, the diagonal beams I 9 extend beyond the corner members l8 at the rear of the apparatus and are connected by a transverse channel member 2| which also serves to support a bracket 22 which receives a mast 23 when the latter is not extended vertically as in Figure 1. The mast 23 forms no part of the present invention and is merely shown in Figure 1 for convenience with the top broken away. It will be understood that this mast carries the usual sheaves at the top thereof and is adapted to be moved around the pivot 24 from the position shown in Figure 1 to a horizontal position in which it is supported by the bracket 22.

Mounted adjacent the rear end of the side frame members is a power unit 25, which in this instance comprises an internal combustion engine of the usual type having the customary crankshaft, camshaft and flywheel (not shown), and having a drive shaft 26 extending laterally and outwardly of the frame, which shaft has fixed thereto for rotation therewith a sheave 21 provided with a plurality of V-grooves adapted to receive a plurality of transmission belts 28 of the V-type. These belts drive a relatively large sheave 29 which is fixed on a countershaft 30 and which is also provided with a plurality of V-grooves to receive the belts. The sheave 29 is made extra heavy to give a flywheel effect and will be later referred to. The engine mounting may be adjustable to permit tensioning of the V-belts, but this feature is not a part of the present invention.

The countershaft 30 is rotatably supported in suitable bearings 3|, preferably of the roller type, on the longitudinal frame members [0, II and I6, and a portion of a bull reel clutch 32 as well as a portion of a spudder clutch 33 is fixedly secured to the countershaft for rotation therewith, as will be understood. A friction wheel 34 is also secured to the countershaft for rotation with the latter.

Bull reel clutch 32 is of the standard multiple disc, gear-tooth-drive, type and need not be described in detail. As shown in Figures 2 and 3, the parts of this clutch are in engagement to drive the sprocket pinion 35 which is rotatably mounted on the countershaft and secured to a portion of the clutch also rotatable on the latter shaft. The clutch may be disengaged to prevent rotation of pinion 35 in the customary manner by moving the discs out of engagement, and this is accomplished by sliding the collar 36 axially on the countershaft by means of a yoke 37 having one end of a shifting lever 38 secured thereto. The other end of the lever 38 is secured to a manually rotatable rod 39 which extends beyond the front frame member l2 and terminates in a handle 40 in the usual manner.

Spudder clutch 33 is of the same type as clutch 32 except that more discs are utilized. A pinion 4| is rotatably mounted on the countershaft and is secured to a rotatably mounted portion of clutch 33 whereby this pinion may be rotated when the parts of clutch 33 are engaged as shown in Figures 2 and 3. This clutch may be disengaged in the conventional manner by sliding collar 42 axially through the medium of yoke 43,

shifting lever 44, and rod 45 having handle 46 on the end thereof.

Adjacent the power unit and rotatably mounted on frame members l0 and H is a bull reel shaft 4'5 having a bull reel 48 fixed thereto and divided into sections of different diameter to facilitate handling of the Wire cable 49 which is carried thereby. The bull reel is driven by a sprocket wheel 50 secured thereto which is connected to sprocket pinion 35 by a drive chain 5|, whereby the bull reel is driven when the parts of clutch 32 are engaged. To assist in controlling the speed of rotation of the bull reel a brake of the external contracting type is associated with the bull reel and this brake is designated generally by numeral 52 since the parts are conventional and need not be referred to in detail. The brake is controlled by handle 53 located adjacent handles 40 and 46, through rock shaft 54, crank 55,

, rod 56 and bell crank lever 51 in the customary manner.

A sand reel 58 is mounted for rotation between side frame members l0 and II adjacent the front of the machine and is adapted to be frictionally driven by contact with friction wheel 34. Hand lever 59, adjacent handle 53, is adapted to move the sand reel into contact with the friction wheel and out of contact with the latter into contact with the brake band 60. The operation of the sand reel in this manner is well understood in the art and the details of the parts need not be referred to as they form no part of the present invention.

Coming now to the parts of the apparatus carried by the superstructure it will be noted that the vertical frame members l8 at the rear of the machine have longitudinally extending brackets 6i secured thereto and a shaft 62 is fixed between these brackets. A spudder sheave 63 is mounted for rotation on shaft 62 and a pair of spaced spudder arms 64 each have their rear end mounted for limited rocking movement about shaft 62. The front end of each arm 64 is pivotally connected as at 65 to one end of a pair of spaced pitmans 66 the opposite ends of which are pivotally connected to a pair of spaced crank arms 6! which are fixedly secured to a rotatable crankshaft 68 having a gear 69 fixed thereto and meshing with the pinion 4|, the arrangement being such that when the parts of clutch 33 are engaged the pinion 4| will rotate the gear 69 and cause the front end of each spudder arm 64 to move continuously up and down in an arcuate path about the shaft 62. It should be noted that crankshaft 68 is placed in back of countershaft 39 rather than in front thereof as this arrangement balances the pull on the pitmans against the gear tooth driving load with the result that these loads tend to neutralize each other with less strain on the crankshaft bearings and frame. Also, the double pitmans balance the load in the center of the machine.

It should also be observed (see Figure 1) that the pitmans 66 are not connected with the spudder at a point directly above the crankshaft as is customary in apparatus of this type, but are connected at points substantially ahead of the crankshaft, the result of this arrangement being that the pitmans will never assume a vertical position at any time during their movement. This angular positioning of the pitmans divides the circle of movement of the crank so that the arc of travel for the pickup stroke (about 200) is greater than for the drop stroke (about 160). Thus an inherent drilling motion is permanently iii) obtained by this arrangement. This feature is important since the. quick drop permits the tools on the end of the line to strike a sharp blow under all conditions without being affected by variations in the load.

Referring now to the shock absorbing mechanism, which preferably is placed in the spudder, it will be seen (Figures 2, 4 and 5) that each arm 94 is formed substantially as a housing, open at predetermined points, to receive the shock absorbing parts. Since the arrangement in each arm 84 is identical, a description of one will be sumcient. As shown in Figure 5, a rear guide bearing member 19 is adjustably mounted at the rear of arm 84 wherein slots H are provided to receive transverse spaced bolts 12 which extend through the bearing member and the slots, being secured therein by nuts 13. Longitudinal bolts 14 are also provided and extend through the bearing member and suitable lugs 15 carried by arm 84, being held by nuts 18. The bearing member 19 slidably receives one end of a longitudinally extending bar 11 having a slidable spacing collar 18 intermediate its ends, the opposite end of said bar being received in a cap 19 and secured therein by a pin 89, said cap being slidable in a fixed bearing. member 8I. A shoulder 95. is provided on cap 19 to receive one. end of a coil spring 83 the opposite end of which bears against collar 18. A second coil spring 84 is arranged between collar 18 and bearing member I9, and preferably, but not necessarily, the convolutions of the springs extend oppositely to each other. It will be apparent that springs 83 and 89 will be compressed when bar 11 is moved toward the rear of the spudder arm. Obviously a single spring could be utilized in place of the two springs and collar illustrated.

A pin 85 is suitably secured against rotation between the walls of the housing arm 64, adjacent the front thereof, and rotatably receives one end of an arm 89, the other end of which receives a fixed shaft 81 mounted between the two arms 99, said shaft rotatably carrying a front spudder sheave 98. As shown in Figure 5, each arm 88 extends beyond its adjacent arm 64 and by virtue of its pivotal connection with arm 84 is capable of limited relative turning. movement with respect to the latter arm. Beneath each arm 89 is a rubber supporting member 89 on which the arms 8i rest in their lowermost positions. The rear surface of each arm 89 is arcuate shaped as indicated at 99 so as to be utilized as a cam surface, which surface is extended substantially as shown at 9!. The arc for the surface 99 centers, not in pin 85, but at a point 9| intermediate pin 85 and shaft 81, for a purpose to be described. A floating shoe, indicated as a whole by numeral 92, is arranged between arm 86 and the end of cap 19, a portion 93 of said shoe being adapted to engage cap 19 while a portion 94 thereof is adapted to engage arm 86, being provided with a cam surface 95 complementary to the cam surface 99. The portion 94 is mounted for limited turning movement about a pin 96 fixedly mounted in the portion 93.

Referring now to Figure 1, the spudder is shown in two positions whereby the relative turning movement between arms 84 and 86 instantly will be apparent. As the spudder moves from the lower to the upper position shown and the arm 89 turns about pin 85, the shaft 81 and sheave 99 will turn about an arc the center of which will be the pin 85, and since the arc of cam surface 99 is located at 9|, said surface in cooperation with cam surface 95 will move shoe 92 a substantial distance toward springs 83 and 84, thereby compressing thesprings. To more clearlyillus trate this movement of shoe 92, an are 91 has been drawn with a radius equal to the distance between the centers of shaft 82 and pin 98 in the lower position shown. When this arc is extended to the upper position, the movement of pin 96 is readily discernible.

In Figure '7 I have shown diagrammatically the relationship between pins 85 and 96, and point 9I. During pivotal movement of arm 88 from its lower position to its upper position, point 9| will travel in the arc of a circle which centers in shaft 85 and said point will move substantially equal increments as shown at a, b, c, d and 6. However, pin 99 will move unequal increments as shown at a', b, c, d and e, the movement being in increasing increments as pin 99 moves towards springs 83 and 84, because initially point 9| is moving a greater distance vertically than horizontally but as it proceeds around the are its movement becomes more horizontal than vertical. As a result of this novel arrangement the leverage between shaft 81 and the springs varies and in actual practice this leverage can be varied from approximately 16 to l at the start of the stroke to approximately 2 to 1 at the end of the stroke. Of course, the movement and effect of pin 98 and point 9| is reversed when arm 86 pivots downwardly. I am not aware. of any well drilling apparatus which can employ as much leverage as is utilized in my device or which can vary the leverage in any way. Because of this greater leverage and variable leverage principle I may use relatively heavy springs 83 and 84 and can move them with lower drill line tension by having the shaft 81 and its sheave 88 travel a greater distance.

Another feature of my invention is illustrated in Figures 1, 2 and 6, wherein the numeral I99 designates the carburetor of the power unit 25 which has a fly weight governor I9I associated therewith. A rod I92 has one end connected to the usual throttle valve in the carburetor and its other end connected to one end of arm I93. The latter is fixed to a rock shaft I94 which also has a depending arm I95 fixed thereto. Between arm I93 and a flange I95 on the governor housing is a compression coil spring I91 which is 1 adapted to urge arm I93 away from the flange to open the carburetor throttle, which movement urges arm I95 toward a sleeve I98 slidably mounted on a shaft I99. Shaft I99 is rotatably mounted in the governor housing and has a portion extending outwardly thereof to which a gear H9 is fixed, said gear being in mesh with suitable gearing (not shown) driven by the cam shaft of the engine. Mounted for rotation with shaft I99 are the customary fly weights III which are adapted to be moved in and out by centrifugal force as will be understood. Outward movement of the fly weights is adapted to slide sleeve I98 toward arm I95 and to move the latter arm, shaft I94 and arm I93 against the action of spring I91 and consequently to close the throttle valve.

Initially I set the throttle valve for running the engine at a rate of Speed determined to be suitable for the job to be performed. This is done manually by a pin II2 which extends through an opening in flange I99 and has an enlarged end II3 bearing against spring I91, the other end of said pin being engaged by one end of lever II I which is pivoted as at I I5 to a lug II8 carried by flange I96. The other end of lever H4 is swivelly connected asat II! to a'rod |I8.which inturn is connected to a lug II9. carried by a nut I20 through which extends the threaded end I2I of a manually rotatable shaft I22. The arrangement of nut I20 is such that when shaft I22 is turned the nut will move on the threaded end of the shaft and move rod II8 to vary the force applied by lever II 4 against pin II2. I providefor manual turning of shaft I22 from a point adjacent the other controls of the apparatus by fixing a small pulley I23 on the end of the shaft outwardly of the supporting frame, which pulley is connected by a flexible cable I24 to a second pulley I 25 mounted on one of the vertical frame members I8 at the front of the machine, whereby rotation of pulley I25 will turn shaft I22.

It will be apparent that the throttle may be initially set by turning pulley I25 and if the engine tries to speed up due to a lessening of the load the flyweights will be moved outwardly and sleeve I08 moved to cut down the flow of gas through the throttle. As the gas is cut down the speed of the engine will be reduced, the flyweights will move inwardly and spring I01 will open the throttle. Likewise, if the engine tries to slow down, as on the tool pickup stroke, the fiyweights will move farther inwardly and pull sleeve I08 so that spring I01 will open the throttle to increase the speed of the engine, which increase will move the flyweights outwardly and tend to return the throttle to the initial position. Thus it will be seen that one of the functions of the governor is to open and close the engine throttle so that the power delivered by the engine will be varied to meet the power demand. Also, the governor tends to maintain the engine speed substantially at the rate initially determined to be suitable.

In operating this apparatus, the wire cable 49 extends upwardly from bull reel 48, passes over sheave 63 and under sheave 88 from which it extends upwardly to the top of mast 23, passing over one of the sheaves at the top of the mast and carrying the drilling tools in the conventional manner. By virtue of my novel shock absorbing means I have substantially reduced the drilling line working tension and have neutralized to a great extent the shock of the tool pickup by having a variable leverage which rapidly changes as the work of stopping the falling tools proceeds so that I get a quick pickup. Also, due to the relative turning movement between arms 64 and 86, at the start of the pickup stroke arms 64 will start moving downwardly while arms 86 are still moving upwardly, thereby allowing a time interval at the start of the pickup stroke during which the springs 83 and 84 receive energy from the tools to neutralize the shock of pickup. In other words, I have allowed the time and provided the leverage necessary properly to handle the load.

It will be obvious that I am absorbing and conserving the unused tool energy by storing it in the shock absorber springs during the last part of the drop stroke at which time the spudder reaches its uppermost position, and then using it again during the pickup stroke while the spudder is moving downwardly. During the pickup stroke while arms 64 are traveling downwardly arms 86 also travel downwardly and the rebound of springs 83 and 84 imparts additional force and movement to the tools on the end of the line. However, it should be noted that during the rebound of the springs the shoe 93 and its cam face act as a snubber or brake and permit a smooth, controlled action rather than an undesirable, instantaneous rebound of the springs. Tests have shown that I can actually get more than half of the required power used on the pickup stroke out of the shock absorbing means using energy which would be expended in shock and wear and tear on the machine if the shock absorber was not used.

The unique drilling motion obtained with my apparatus should also be noted. In operating apparatus of this type, the peak load power necessary is not furnished entirely by the power plant. Of course, it is possible to use a power plant large enough to supply the peak load requirements, but such plant would be impractical since most of the cycle of operation requires considerably less than peak power. Therefore, it is desirable to use a power plant giving at full throttle insufficient power to meet the peak load requirements and supplement this engine power with energy from other sources. This supplemental energy in my apparatus is obtained from the power plant during that portion of the cycle in the operation that does not require the maximum power obtainable from the engine. For example, during the drop stroke, the energy not utilized is stored in the countershaft flywheel, from which it can be drawn to supplement the engine power when peak power is required. The proper size and weight of the countershaft flywheel can be determined mathematically after it is known what peak power requirements are needed. The inertia of the countershaft flywheel is utilized as soon as-the engine starts to slow down under the action of the pickup stroke. Then as the flywheel tends to slow down, the governor goes into action opening the engine throttle and increasing the speed of the engine and consequently tending to replace in the countershaft flywheel the energy drawn therefrom. One of the functions of the governor is to open and close the throttle'so that the power delivered by the engine will vary with the power demand. One of the functions of the countershaft flywheel is to maintain a constant speed of the countershaft and therefore the timing of the machine. This it does by acting asa reservoir from which energy is drawn. In summing up the benefits of my drilling motion I would like to point out that it does not depend upon a speed variation of the power unit which can only be built for average conditions and is therefore not suitable for all conditions. It does not vary greatly with the depth of the hole, being as good a motion at the surface as when deeper. It is affected little by variations in drilling tool weight and it is automatically controlled for variation of power requirement, being, therefore, adaptable to variation in the formations drilled.

My governor control is different from the usual control in that it is not just a maximum speed limiting governor but one that will maintain the engines speed anywhere in its whole range and still permit development of the full power of the engine if the load demands it. Since the engine 25, countershaft 30 and crankshaft 68 run at practically constant speed due to the governor control and the inertia effect obtained from the countershaft flywheel, I obtain the proper variation in speed of the drilling tools by connecting the pitmans 66 to arms 64 at points substantially ahead of the crankshaft, and by virtue of the relative movement between arms 64 and 8E, I can obtain an independent movement of arms 96 actuated entirely by the falling tools.

Although I have illustrated and described the preferred embodiment of my invention, it will be apparent to those skilled in the art that the invention is not so limited but that various modifications may be made therein without departing from the spirit of the invention or from the scope of the subjoined claims,

What is claimed is:

1. In drilling apparatus, in combination, a power unit, a spudder arm operated by the power unit, a sheave carrying arm pivoted to said spudder arm and capable of relative pivotal movement with respect to said spudder arm, a shock absorber carried by said spudder arm, and cam means for operating said shock absorber, said cam means being operable by said relative pivotal movement of said sheave carrying arm.

2. In drilling apparatus, in combination, a power unit, a spudder arm operated by the power unit, a sheave carrying arm pivoted to said spudder arm and capable of relative pivotal movement with respect to said spudder arm, said sheave carrying arm having a cam surface thereon, a shoe adapted to be moved by engagement of said cam surface therewith during relative movement of said sheave carrying arm, and springs opposing movement of said shoe.

3. In a spudder, an arm mounted for predetermined pivotal movement, a sheave carrying arm mounted on said first arm for relative pivotal movement with respect to said first arm, a shock absorber carried by said first arm, and cam means for operating said shock absorber, said cam means being operable by said relative pivotal movement of said sheave carrying arm.

4. In a spudder, an arm mounted for predetermined pivotal movement, a sheave carrying arm mounted on said first arm for relative pivotal movement with respect to said first arm, said sheave carrying arm having a cam surface thereon, a shoe adapted to be moved by engagement of said cam surface therewith during relative movement of said sheave carrying arm, and springs opposing movement of said shoe.

5. In a spudder, an arm mounted for predetermined pivotal movement, a sheave carrying arm mounted on said first arm for relative pivotal movement with respect to said first arm, said sheave carrying arm having a cam surface thereon, a shoe having a cam surface complementary to said first-mentioned cam surface and adapted to be moved by engagement of said cam surfaces during relative movement of said sheave carrying arm, a rod movable by said shoe, and springs surrounding said rod and adapted to be compressed by movement of said rod.

6. In a spudder, an arm mounted for predetermined pivotal movement, a sheave carrying arm mounted on said first arm for relative pivotal movement with respect to said first arm, a variable leverage shock absorber carried by said first arm, and cam means operable to vary the leverage of said shock absorber.

'7. In a spudder, an arm mounted for predetermined pivotal movement, a sheave carrying arm mounted on said first arm for relative pivotal movement with respect to said first arm, a variable leverage shock absorber carried by said first arm, and cam means operable to vary the leverage of said shock absorber, said cam means being operable by said relative pivotal movement of said sheave carrying arm.

8. In a drilling apparatus, in combination, a power unit, a spudder arm operated by the power unit, a sheave carrying arm pivoted to said spudder arm and capable of relative pivotal movement with respect to said spudder arm, a variable leverage shock absorber carried by said spudder arm, and cam means operable to vary the leverage of said shock absorber.

9. In a drilling apparatus, in combination, a power unit, a spudder arm operated by the power unit, a sheave carrying arm pivoted to said spudder arm and capable of relative pivotal movement with respect to said spudder arm, a variable leverage shock absorber carried by said spudder arm, and cam means operable to vary the leverage of said shock absorber, said cam means being operable by said relative pivotal movement of said sheave carrying arm.

10. In drilling apparatus, in combination, a power unit, a spudder arm operated by the power unit, cushioning means carried by said spudder arm, a sheave mounted for pivotal movement with respect to said spudder arm, and variable leverage mechanism mounted on the spudder arm and interposed between the sheave and said cushioning means.

11. In a spudder, a spudder arm, cushioning means carried by said spudder arm, a sheave mounted for pivotal movement with respect to said spudder arm, and variable leverage mechanism mounted on the spudder arm and interposed between the sheave and said cushioning means.

GEORGE HEINISI-I.

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