US2694319A - Resilient pitman bell crank - Google Patents

Description

. Nov. 16, 1954 A. H. JOHNSON RESILIENT PITMAN BELL CRANK Filed Jan. 8, 1951 3 Shets-Sheet l IIIIIU 3 rmentor NOV. 16, 1954 A, H JOHNSON 2,694,319

RESILIENT PITMAN BELL CRANK Filed Jan. 8, 1951 3 Sheets-Sheet 2 3 nventor Nov. 16, 1954 A. H. JOHNSQN RESILIENT PITMAN BELL CRANK 3 sheetsesheet 3 Filed Jan. 8 1951 United States PatentO RESILIENT PITMAN BELL CRANK Ax'el H. Johnson, Racine, Wis., assignor to' J. I. Case Company, Racine, Wis., a corporation of Wisconsin Application January 8, 1951, Serial No. 204,862

7 Claims. (Cl. 74-559) This invention relates to harvesting machines'and especially to the means for reciprocating the sickle attached to such machines. Specifically, this invention concerns an improvement in the bell crank employed to change the direction of actuation from a fore-and-aft reciprocation to one transverse to the direction of travel of the machine.

An object of this invention is to provide a means of reducing the shock incident to the reciprocation of harvester machine sickles.

Another object is to simplify the construction of devices of this nature by adopting a construction in which duplicate parts are employed thus simplifying inventories and making for economy in manufacture.

Another object is to provide a device ofthis nature which can be made of lighter components thus directly reducing the reciprocating mass and thereby minimize the tendency for failure of various members in the machine owing to excessive vibration.

Another object is to provide a device whichwill be quiet in operation owing to an absence of vibration.

Another object is to provide a device of this nature which will have a smooth, more positive cutting action as a result of the absence of vibration.

Further objects and advantages of the inventionwill become apparent from a consideration of the following detailed description taken in connection with the accompanying drawing wherein a satisfactory embodiment of the invention is shown. However, it is to be understood that the invention is not limited to the details disclosed but includes all such variations and modifications as fall within the spirit of the invention.

A serious problem generally prevalent concerning drives for reciprocating sickles and similar devices is the damage caused by vibration. This damage generally increases as the rate of reciprocation increases.

Damage to reciprocating mechanisms is mainly caused by the shock incident to the sudden reversal of direction of the various members. The damage takes on several forms, one being that bearings are quickly worn out of round with the result that the machine becomes noisy. Worn bearings encourage vibration which in turn causes wear in other parts of the implement.

Another form of damage prevalent in reciprocating mechanisms is that caused by bolts and other fastenings becoming loose which in turn result in the loss of members of the implements. Such loss of one member may cause damage to another, even in remote portions of'the implement.

Vibration frequently interferes with the proper functioning of the sickle in that its cutting function is impaired, the vibration preventing continuous contact between the sickle and the knives.

It is believed that this invention reduces the vibration of the sickle drive of harvesters. mowers and the like by providing a bell crank arranged so that the shocks incident to this type of mechanism are substantially absorbed.

Referring to the drawings:

Fig. 1 shows a fragmentary front view of an element having parts broken away and showing the invention;

Fig. 2 shows a bell crank incorporating'the invention and detached from the implement;

Fig. 3 is a fragmentary view-of the lower support block for the bell crank;

Fig. 4 is a plan viewof the upper crank arm;

Fig. '5 is an elevational' view ofthecrankarmeas':

shown in Fig. 4;

Fig. 6 is a modification ofthe bell crank shown inFigsa land 2;

Fig. 7 is a view showing. the means by which-shocks are absorbed, and Fig. 8 is another modification.

Referring to the drawings, 10 isthe' frame of an implement, in this instance, a windrower; This frame generally comprises angle members, plates and other-nee essary elements which go to'make up machines of this nature. 7

A crank member 11 is employed to provide theymeans for reciprocating the'sickle and is driven through chain and sprockets and not shown on-the'='drawings, bemg:

must be resolved to one parallel to the axis of the crank 11. The sickle is generally designated" as 12 and extends transversely to the direction oftravel 12 of the imple-- ment as shown in Fig. 1. I

In instances such as that under consideration, a bell crank such as at 13 is employed.

bell crank 13 and a pitman 15 connects the sickle 12 with the bell crank 13.

The invention will now be described in detail.

Frame 10 has provided thereon parallel plates 16 and 1.7 the latter being spaced above the plate 16 as-shown in Fig. 1. Plates 16 and 17 are secured to frame 10 by rivets 18 and 19. Plates 16 and 17 function as supports for clamping blocks 20 and-21 respectively. Blocks 20 and 21 support the" bell crank 13 as'shown in Figs. 1 to 3 and have a slit 22 and 23in order that the spindle of the bell crank 18 may be clamped against displace-- ment. Blocks 20 and 21' are secured to plates Hand 17 by welding in this instance as shown in Figs. 1 to 3 in a manner specifically shown in- Fig. 3. 27 and 28 of block 20 are welded to plate 16 leaving the other edges free. Block 21 is similarly secured toplate 17. Bolts 29 and 30 serve to'draw the halves of blocks 20 and 21 together thus clamping the spindle 24 against axial displacement or rotation. 7

As shown in Figs. 1 and 2, the invention comprises mainly an improved bell crank 13. As mentioned before, bell crank 13 is journalled upon the spindle=24. Bell crank 13 comprises in this instance, an upper crank arm 31 and a lower crankarm 32 separated a suitable distance apart on the spindle 24. A reference to Figs. 1 and 2 indicates that the bell crank 13 has the crank arms-disposed at an angle of about degrees relative to each other on the spindle 24. This position is necessary in order to conform to the design of the implement, the

motion of the pitman 14' being at right angles to that of the pitman 15. However, the relative positions of the crank arms can be varied to suit individual require ments.

Crank arm 31 is of'ca'st steel or a forging, the method of manufacture being dictated by the quantity required. A disc portion 33 comprises the main portion-of the hub portion of crank arm 31 and is made of substantial thick ness to assure sufli'cient strength and support for othercommunicates with and lubricates the bushing 35.

Disc portion 33 has extending therefrom a web 37 which is substantially at rightangles to the axis of. spindle 24. A pitman-bearing ball portion 38 terminates the web 37 and is an integral part thereof.

Disc portion 33 is provided with notches or slots 39 and 40 in the periphery th'ereof'positioned at degreesapart asshown in Figs. 2 and 4. In thisinstance slots 39 and 40 pass en'tir'ely through the disc portion 33';

parallel to the axis ofspindle 34.

Patented Nov. 16, .1954

To complete theassembly a pitman 14 connects the crankll-with the Two edges Crank arm 31 is so designed that it can be also used as crank arm 32 by merely rotating the former 180 degrees about the axis 41 as shown in Fig. 4, and then counterclockwise an angle of 90 degrees as indicated by arrow 42. Whencrank arm 32 has been thus positioned on the spindle 24, the slots 39 and 40 of crank 31 will be aligned with corresponding slots in crankarm 32 as shown in Figs. 1 and 2. The web of crank arm 32 is designated as 37 and the bell pitman bearing portion is designated as 38. Substantial economies in manufacture are thus possible.

The means of obtaining a unitary assembly is to connect bell cranks 31 and 32 by torsional members 43 and 44 which, in this instance, are rectangular in cross section. The relationship of the effective length L to width W, thickness T and amount of separation D of torsional members 43 and 44 is a question of mechanical design involving the skill of one acquainted with the art, and is dictated by various factors peculiar to the specific implement involved: The mass of the reciprocating parts and the rate of oscillation also being deciding factors.

The width W may be such that the torsional members will protrude beyond the periphery of the disc portion 33 of the crank arms 31 and 32. This is a matter of design and within the skill of one acquainted with the art.

Torsional members 43 and 44 should be welded or otherwise secured in the- slots 39 and 40 so that crank arms 31 and 32 and torsional members 43 and 44 form a unitary assembly.

Bell crank 13 is mounted as shown in Fig. 1 with the crank arm 31 directed approximately parallel to the axis of the crank member 11. The pitman 14 connects the crank member 11 with the ball portion 38. The crank 32 is directed forwardly in the direction of arrow 12 and at right angles to the direction of reciprocation of the sickle 12. Sickle 12 has afiixed thereto a ball pitman bearing 45, and the sickle pitman connects ball 45 and the ball pitman bearing portion 38.

On inspection of Fig. 1 it will appear that rotation of crank member 11 will effect reciprocation of sickle 12. The sudden shocks owing to the change .in direction of movement of the several members will be substantially absorbed by a combined twisting and bending of the torsion members 43 and-44. This effect is graphically shown in Fig. 7 which shows torsion member 43 in its twisted state resulting from a shock induced by reciprocating forces. A substantial amount of the shock has been absorbed before the motion is reversed. The angle 46 of Fig. 7 is less than that between the crank arms 31 and 32 when the sickle 12 is at rest. Torsion member 44 is not shown in Fig. 7 in that the showing of member 43 is sufficient to explain the function of the invention, both members 43 and 44 being subjected to like forces.

Fig. 6 shows a modification in-which the disc member 48 has cylindrical recesses formed on theperiphery thereof, other details of the'crank arm 50 being similar to the crank arm 31 shown in Fig. 2. Torsion members 52 and 54 are of cylindrical cross section and are secured by welding in this'instance, to the disc member 48 in the recesses above mentioned, the welding, being done at points on each side of the recesses as at 56 and 58. A second crank arm is provided similar to arm 50 and the assembly completed as in the manner shown in Fig. 2.

Fig. 8 shows a simplified 'modification of the invention. In this instance the hub portion 60 has no notches in the periphery thereof: The design of crank arm 62 being otherwise similar to that of crank arm 31.

Torsional members 64 and 66 are tangentially located on the periphery of the hub portion 60 as shown in Fig. 7. and welded or otherwise securely fastened thereto to form a unitary bell crank.

Summarizing the invention it will be understood that shocks incident to reciprocating the sickle 12 under normal conditions will result in injurious shocks to the actuating mechanism. When the bell crank 13 which embraces this invention, is employed the reciprocation will set up a series of relative angular oscillations of the crank arms 31 and 32. These oscillations will be resisted by the torsional members 43 and 44 of Fig. 2, but owing to the natural resiliency of the members 43 and 44 there will be a slight relative rotation of arms 31 and 32 about the axis of the spindle 24, resisted only by the resistance to bending of the members 43 and 44'. The slight relative rotation of arms 31 and 32 and the consequent bending or flexure of members 43 and 44 will be sufiicient" to absorb the more substantial shocks tending to injure the mechanism;

The above being a complete description of an illustrative embodiment of the invention, what is claimed as new and desired to be secured by Letters Patent of the United States is:

1. In a shock absorbing sickle actuating means for a harvester having a frame, and a spindle fixed uprightly against rotation on said frame, the improvement comprising a bell crank on said spindle having an upper and a lower crank arm, each of said arms provided with bushings and independently journalled on said spindle and spaced apart thereon, each of said crank arms provided with hub portions concentric with the axis of said spindle and a pair of slots disposed on the periphery of each of said hub portions at diametrically opposed positions, corresponding slots in said hub portions being mutually aligned, a pair of torsion members extending betweensaid hub portions and secured unitarily at their extremities in said slots to connect said crank arms for limited relative shock absorbing rotation independently of said spindle by distortion of said torsion members, said torsional members protruding beyond the periphery of said hub portions.

2. A shock absorbing bell crank for actuating a sickle on a harvester, the improvement comprising a spindle fixed against rotation on said harvester, and supporting said bell crank, said bell crank comprising upper and lower radially extending crank arms, each of said arms being independently journalled on said spindle and axially spaced apart thereon, each of said arms provided with a pair of axially extending slots on the periphery thereof, the slots of each of said arms being aligned with corresponding slots of the other arm and a pair of torsion members connecting said arms and permanently fixed in said slots to allow limited relative shock absorbing rotation of said arms freely about said spindle by distortion of said torsion members.

3. A shock absorbing bell crank for actuating a sickle ona harvester, comprising a spindle fixed against rotation on said harvester and supporting said bell crank, said bell crank comprising a pair of crank arms, each being independently journalled on said spindle and axially spaced apart thereon, each of said arms provided with a pair of axially extending slots on the periphery thereof, the slots of each of said arms being aligned with corresponding slots of the other arm, and a pair of torsion members permanently connecting said arms and terminating in said slots to allow relative shock absorbing rotation of said arms freely about said spindle by distortion of said torsion members, said torsional members lying in radial planes.

4. A shock absorbing bell crank for actuating a sickle on a harvester, comprising a pivot means for said bell crank, said bell crank having a pair of crank arms, each being independently journalled on said pivot and axially spaced apart thereon, each of said arms provided with a pair of axially extending semi-cylindrical notches on the periphery thereof the notches of each of said arms being aligned with corresponding notches of the other arm, and a pair of cylindrical torsion members connecting said arms and permanently secured in said notches to allow limited relative shock absorbing rotation of said arms freely about said pivot.

5. A shock absorbing bell crank for actuating a sickle on a harvester, comprising a fixed pivot means for said bell crank, said crank having a pair of crank arms, each being independently journalled on said pivot and axially spaced apart thereon, each of said arms being provided with a hub portion normal to the axis of said pivot and co-axial therewith and a pair of torsion members permanently and integrally connecting said hub portions and spaced adjacent the periphery thereof and forming an integral unitary assembly allowing limited relative shock absorbing rotation of said arms freely about said pivot means.

6. A shock absorbing bell crank for actuating a sickle on a harvester, comprising a fixed pivot means for said bell crank, said crank having a pair of crank arms each being independently journalled on said pivot and axially spaced apart thereon, each of said arms being provided with a hub portion surrounding the axis of said pivot means, at least one torsional member intermediate said hub portions and secured integrally adjacent the peripheries thereof resulting in a unitary assembly limited to relative rotation of said arms freely about said pivot means by bending and distortion of said torsional member.

7. A shock absorbing bell crank for actuating a sickle on a harvester, comprising a fixed pivot means for said bell crank, said crank having a pair of crank arms each being independently journalled on said pivot and axially spaced apart thereon, each of said arms provided with a hub portion, a torsional member intermediate said hub portions and secured integrally about the peripheral surface thereof resulting in a unitary assembly limited to relative rotation of said arms about said pivot means to that permitted by the bending and distortion of said torsional member.

References Cited in the file of this patent UNITED STATES PATENTS Name Da Number Number Name Date Bacon Nov. 9, 1869 Crowther Feb. 8, 1876 Morris Apr. 19, 1898 Trufant Jan. 20, 1914 Hobbs July 10, 1917 Welker Jan. 13, 1925 Dante Dec. 8, 1931 Stone Feb. 9, 1932 Fulton Apr. 24, 1945 FOREIGN PATENTS Country Date Norway Dec. 27, 1943 Great Britain Oct. 22, 1906 Great Britain July 3, 1924

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