US2950798A

US2950798A - Safety cut-off for pump pitman

Info

Publication number: US2950798A
Application number: US748975A
Authority: US
Inventors: Tom L Abbott
Original assignee: Individual
Current assignee: Individual
Priority date: 1958-07-16
Filing date: 1958-07-16
Publication date: 1960-08-30
Anticipated expiration: 1977-08-30

Description

Aug. so, I1960 2,950,798

T. L. ABBOTT SAFETY CUT-OFF FOR PUMP PITMAN Filed July 1e,` 1958 2 sheets-sheet 1 33 FlgJ x'l"|,y|l 34' 24 40 e o l /4 O 49 46 /0 46 76 7am L. Abba# IN VEN TOR.

ana/M 5mm Aug. 30, 1960 T. 1 ABBOTT SAFETY CUT-OFF FOR PUMP PITMAN 2 Sheets-Sheet 2 Filed July 16, 1958 Tom L. Abboff INVENTOR.

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. This invention comprises a novel and useful safety cutoi for pump pitman and more particularly relates .to a safety `device for automatically stopping the power operating means of a pumping rig when the pitman of the same is disconnected from its actuating crank.

VIn oil well pumping rigs it is customary for the individualV Well to have its pump sucker rod string operated from a walking beam by a pitman connected to an individual source of power for the oil well. Usually, automatic control means are provided for actuating the pumping mechanism by the source of power at predetermined time intervals. Frequently, such pumping rigs are left unattended for several days. Accordingly, in the event that a pitman breaks or becomes `disconnected from the crankshaft of its operating mechanism, the source of power is automatically reenergized at the selected predetermined time intervals and operating unattended frequently causes considerable damage.

lt is therefore the primary purpose of this invention to provide an automatic safety device which may be applied to the pitman of an oil ywell pumping mechanism for automatically deactivating the electric motor constituting the source of power in the event that the pitman becomes detached from its crankshaft of the actuating mechanism.

A further object of the invention is to provide a safety device o'f simple construction and which may be readily applied to the conventional structure of an oil well rilmpns Iig- These together with other objects and advantages which will become subsequently apparent reside in the details of construction 'and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings for-ming a part hereof, wherein like numerals refer to like parts throughout, and in which:

Figure l is a perspective view of a pumping unit and showing the manner in which the safety device of the present invention is applied to the pitman and associated structure thereof;

Figure 2 is an enlarged detail view taken in vertical section substantially upon the plane indicated by the section line 2-2 of Figure l and showing in particular the manner in which the safety device is connected to the crankshaft of the pumping mechanism -to which the pitman is connected;

f Figure 3 is a perspective view showing the manner in which the safety device is operated when a pitman becomes Vdetachedlfrom its connecting rod;

Figure 4 is a vertical transverse sectional view taken substantially upon the plane indicated by the section line 4-4 of Figure 2; and, p

Figure 5 is a further detailed View taken in horizontal section substantially upon the plane indicated by the section line 5 5 of Figure 4.

In the accompanying drawings there is indicated generally by the numeral .110 -a conventional type of an oil well pumping rig, by means of which a source of power -Patented Aug. 30, 1960 2 such as an electric motor 12 is caused to periodically at predetermined time intervals reciprocatory movement to a sucker rod string 14 by which the pump, not shown, is operated. The pumping rig includes a supporting base or stand 16 having a pedestal 18 thereon upon which the motor or source of power- 12 is mounted. Also carried by the stand is a pump jack or gearing assembly generally indicated by the numeral 20 and which may be of any conventional design, the same being con? nected to the source of power y12 as by a pulley or other drive at 22. The motor is supplied with power from any suitable source by means of an electrical circuit, the same including the conducting cables 24. f

It will be understood that the motor circuit m-ay include the usual `adjustable timing device whereby the motor is actuated at predetermined time intervals for a predetermined duration in order to cause the pump to thereby discharge the accumulation of oil or water from the bottom of the wel-l bore.

The stand 16 is provided with a `further supporting framework as at 30 and a walking beam 32 is pivoted to this framework .as by a pivot pin 34 intermediate the ends of the walking beam. As will be observed, one end of the walking beam is secured as by ia strap 36 to the upper end o-f the sucker rod string 14, while the other end of the walking beam has an adjustable counterbalance or counteiweight as at 38. Between the pivot 34 of the walking beam and the counterweight, a U-shaped connecting rod or pitman ydesignated generally by the numeral 40 is pivotally connected to the walking beam as at 42, and is provided -With a pair of pitman arms as at 44, Whose lower ends are pivote-d to a pair of crank arms 46 carried by the crankshaft 49 constituting the power output shaft of the pump jack 20'.

As shown more clearly in Figure 2, each of the crank yarms 46 adjacent its outer end has a crank pin 48 lsecured thereto and the pitman `arm 44 is journaled on the projecting extremity of the crank pin 48 by means of a bearing assembly 50. It willv thus be apparent that when the motor 12 is operated the crankshaft and the crank arms will be rotated and through the pivotal connection of the pin 48 reciprocation will be imparted to the pitman 40 yand rthus rocking mou'on will be imparted to the walking beam.

It is to this `conventional form of pump actuating mechanism that the safety device of the present invention is applied which is effective to open the circuit of the electric motor y12 whenever the pitman 40 is disconnected from its crank pin 4S, as `suggested in Figure 3.

The safety device includes a conventional form of electric switch 52 `which is xedly mounted in any desired manner upon any desired portion of the pitman. As illustrated, the switch is mounted at the upper cross member of the pitman although it will be understood urged to a circuit open position, there being provided aV switch actuating lever 54, see Figure 3, which may be moved to a position closing the switch and thereby rendering the motor circuit operative under its own controlS. The switch itself is incorporated as by the electric conducto-r 56 intothe circuit of the electric motor for controlling the circuit.

Referring now to Figures 2-5 in particular, it will be seen that there is provided a at plate 60 Awhich is apertured as at 62, to receive the crank pin 48 therethrough, and it is further apertured as at 64 for the reception of a fastening bolt 66 engaged in `a threaded bore 63 whereby this plate is securely attached to one of the crank arms. The plate is attached to the crank arm between the latter and the pitman Iarm 44 as will be best apparent from Figure 2. The plate further includes a pair or arms 70 which embrace therebetween the crank arm 46, and which are clamped to this crank arm as by a strap 72 together with fastening `bolts 74.

Formed upon the plate concentricallly of the crank pin 48 is'an annulus 76, see also Figures 2 and 5, Vwhich. is provided with a peripheral 'groove 78 therein. The outer wall of this groove consists of an outwardly curving an-ge or lip 80 for a purpose to be subsequently set forth. A tension member in the form of a cab1e82 has a lloop S4 at one end seated in `the groove `89` of the annulus 76, and extending through suitable guide brackets 86, is connected by terminal loop 88 to an eye 90 in the end'of a second tension member 91. The member 91 has lan eye 92 interlocked with the eye 9'4 in the end of the switch actuating `lever arm 54. The loop 8S is also interlocked with loop 89 which is supported from pitman arm 44.

The operation of the invention is as follows: With the -pitman in operative position upon the bearing S on the crank pin 4S, the tension member 82 retains the switch -armilever 54 in its `lowered or circuit closing position thereby preventing yoperation of the safety switch 52 and maintaining the circuit of the electric motor 12 in operative condition. However, if for any reason the pitman becomes disconnected from its crank farm, the waiking beam and pitman will then drop under the weight 38. This will reduce the tension upon the tension member 82 and allow the loop S8 to move in rloopl 89 so as to reduce the tension in 4member 91 allowing the switch actuating lever arm 54 to 'be urged into inoperative position by the resilient means within the switch. The lever S4 moves upwardly 'thereby automatically breaking 4the circuit of the electric motor and rendering the pumping rig operative. The loop 39 is fixed to the pitman 4i) and loosely supports the loop 88 'With the loose tit therebetween permitting limited movement of the loop S8. It is necessary to permit limited movement of loop 83 so as to enable the loss of tension on cable .82 to be reliected in the second tension member 9allowing the safety switch 52 to open.

lt will be seen that there is thus relied upon the tensioning eiect `of the tension member 82 to maintain the cutoii switch in a circuit operating condition, and that the tension means is rendered inoperative when a pitman becomes disengaged from its crank pin.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modiiications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may :be resorted to, falling within the scope of the invention as claimed.

Having thus described the invention what is claimed as new is:

l. Pumping ring apparatus of the type having a walking beam mounted for movement about a pivot axis and having one end thereof connected to the sucker rod string of a pump, a pitman pivotally connected to said walking beam on a side of said pivot axis remote from said string for operating the beam, said -beam having a relatively greater weight on the pi-tman side of said axis, a pump jack having a crankshaft with a crank arm ithereon, a crank pin on said crank arm to which said pitman is connected for operation thereby, Ia motor operatively connected to said pump jack; ,the improvement compris- 4- ing a spring urged normally open switch electrically connected to said motor, said switch Secured to said pitman, said switch including a switch actuating lever, and a mechanical tension member connected between said switch lever and said crankpin for closing said switch.

2. Pumping ring apparatus of the type having a walking beam mounted for movement about a pivot axis and having one end :thereof connected to the sucker rod string of a pump, a vpitman pivotally connected to said walking beam on a side of said pivot 4axis remote from said string for operating the beam, said beam having a relatively greater weight on the pitman side of said axis, a pump jack having a crankshaft with a crank arm thereof, a crankpin on said crank `arm to which said pitman is connected for operation thereby, a motor operatively connected to said pump jack; the improvement comprising a spring urged normally open switch electrically connected to said motor, said switch secured to said pitman, said switch including a switch actuating lever, and a mechanical tension member connected -between said switch lever and said crank-pin for closing said switch, said tension member being iiexible and having a closed loop formed on the end thereof remote from said switch lever, a circular peripherally grooved member xed to said crank arm concentrically of said crankpin, said -loop slidably trained around said groove in said circular member with said iiexible member under tension whereby said tension will be released when said pitman becomes disengaged from said crankpin to allow said switch to open.

3. Pumping ring apparatus of the type having a walking beam mounted for movement about a pivot axis and having one end thereof connected to the sucker rod string of a pump, .a pitman pivotally connected to said walking beam on a side of said pivot axis remote from said string for operating the beam, said beam having a relatively greater weight on the pitman side of said axis, a pump jack having a crankshaft with a crank arm thereof, a crankpin on said crank arm lto which said pitman is connected for operation thereby, a motor operatively connected 'to said pump jack; the improvement comprising a .spring urged normally open switch electrically connected to said motor,.said switch secured to said pitman, said switch including a switch actuating lever, and mechanical tension member connected between said switch =lever 4and said crankpin for closing said switch, said tension member being exible `and having a closed loop formed on the end thereof remote from said switch lever, a circular peripherally grooved member iixed to said crank arm concentrically of said crankpin, said loop slidably trained around said groove in said circular member with said flexible member under tension whereby said tension wil-l be released when said pitman becomes disengaged from said crank-pin to allow said switch to open, and guides on said pitman through which said iiexible member is slidably trained to hold said flexible member to said pitman between the ends of said liexible member.

References Cited in the tile of this patent UNITED STATES PATENTS 1,699,663 Hess Ian. 22, 1929 1,704,464 Detwiler Mar. 5, 1929 1,902,492 Dansboe Mar. 21, 1933 2,142,551 A-thy Jan. 3, 1939 2,572,372 Montgomery Oot. 23, 1951