US2584983A - Centrifugally operated switch - Google Patents

Description

Feb. l2, 1952 G. J. BUTTERWORTH CENTRIFUGALLY OPERATEDSWITCH 3 Sheets-Sheet l Filed May 4, 1949 FIG. 3.

JNVENTOR. G/LBERT JMES BUTTERWORTH BY /v @im f ATTORNE S Feb 12, 1952 G. J. BUTTERWORTH 2,584,983

CENTRIFUGALLY OPERATED SWITCH FiledMay 4, 1949 3 sheets-sheet 2 7 INVENTOR.

6 GILBERT JAMES euTTERwoRTH ATTORNE S Feb. l2, 1952 G. J. BuTTERwoRTH 2,584,983

CENTRIFUGALLY OPERATED SWITCH Filed May4 4, 1949 3 Sheets-Sheet 3 G/L ERT JAMES BUT TERWORTH ATTOR Patented Feb. 12, 1,9252

UNITED STATES PATENT CFFICE CENTRIFUGALL'Y OPERATED SWITCH n Gilbert James Butterworth, Chester, Pa., assignor to Sperry-"SurWell Surveying Company, Philadelphia, Pa., a corporation ofDelaware Applica-tion May4, 1949, SerialNo. r91,349

16 Claims. 1

This invention relates to bore hole measuring and more particularly to a centrifugally operated control switch capable of providing repeated closing of an electric circuit such as may be used in connection with .the variousy instruments commonly employed in bore hole measuring apparatus.

In the art of bore hole measuring it is customary to go-devil instruments down into a drill stem and by raising the drill stem `and repeatedly operating the instruments at various levels within the bore holesecure a series of records ofconditions existing within the bore hole correlated with the depths at which the various records were made.

It is common practice to record indications of bore hole inclination, temperature and other characteristics'by photographic or other means which are generally electrically controlled.

Heretofore one of the problems associated kwith the procurement of such a record has been that of providing suitable switching means controllable from the surface of the ground for vterminating the operation of Vthe recording` element or repeatedly initiating the sequence of recording operations at various depth levels. `Such a switch means must not be responsive to vibration, inclination, or impact occurring during the normal passage of the instruments down through the drill stem.

One device desirably used with such aswitching means is that described in the patent to Roland Ring, No. 2,246,319, dated June 17, 1941, and also illustrated in the patents to SmithNo. 2,301,757, dated November l0, 1942, KothnyNo. 2,317,386, dated April 27, 1943, Emerson et al.`No. 2,412,976, dated December 24, 1946, Kothny 2,415,249, vdated February 4, v1947, and Kothny No. 2,424,358, dated July 22, 1947. The Ringinstrument is characterized by a slow continuous marking action, specifically electrolytic in character, whereby a record of the position of the instrument within a bore holeis made only when the instrument remains stationary for uan extended period of time. For a better understanding of the nature of the present invention-which is'not,-however, limited for its application to Vsaid instrument of the above `mentioned patents, the operation of said instrument may be described as follows:

If theinstrument is runinto a borehole, either Within a drill stem or in an openholadbymea'ns of a wire line or cable,-the movements of thelinstrument incidental to its descent intot-he hole cause a. pendulum to -move about relative to a" recordmember, so that even though current is continuously flowing from the pendulum to the record member, no point of the record member is exposed to the current action for a suillciently long time to receive Va definite marking. When the instrument reaches the level at which a record of inclination is to be made, it is brought to rest and held in such position for a period upwards ofabout one minute, with the result that the electrolytic action is concentrated at one point of the record member and an easily distinguishable spot is made thereon. lv'f it is then desired to make one or more additional records at other, levels, the instrument is moved to these successive ylevels and permitted to remain at them for different periods of time, with the result that marks diiering in intensity and/or size are produced which, by their nature, can be identified with the particular levels through a knowledge of the relative times during vwhich the instrument wasstationary. Following the completion of the record or records, `the instrument is then withdrawn continuously from the hole and in this withdrawing movement, as well as in the periods of movement between the successive recordings, the pendulum will swing relative to the record member so that again no obliterating markings are produced. y

rIn thecase of operation of the above type, the instrument is perfectly satisfactory and requires no timing means whatever. However, a. common practice in the making of records with surveying instruments involves their being dropped freely through a drill stem so that they come to rest in a position adjacent the bit. During this location in a position of rest, a record is made Vunder the control of suitable timing means', and the instrument is then recovered when the bit is brought to the surface. Generally speaking,such go-devil records are made at a time when it is necessary to bring the bit to the surface to check the progress of the drill.. .Intheuse of said Ring instrument in go-devil fashion, the motionof the instrument through the drill stem prevents'the making of any record during its fall, and a record is then made by helding the drill stem stationary for a sunlcient period .0f time while the instrument rests ady,jacent the bit. If the drill stem was then raised and dismantled by continuous work of the drilling crew, the instrument would be subject to sui'- ciently continuous agitation, with only quite limitedperiodsv of rest, so that no record obliterating markings would be produced on the record member. However, it is not usual for a derrick crew to work continuously in removing a drill stem from deep holes, and generally speaking, even if some mechanical reason for delay does not occur, the workmen, after raising the drill stem part way, will take a short period of rest before proceeding further. If an instrument of the Ring type is in the drill stem during such a period of rest, or any other period of stationary condition of the drill stem, it will be obvious that another record will be made which might be indistinguishable from the desired record unless a substantially different time of rest is involved, and even then in some rare instances, particularly where the hole is substantially straight, the two records may overlap so that the significance of the original one is lost. It is generally not desirable to rotate the drill stern during such a period of interruption of its withdrawal, and consequently, such rotation is not a practical solution to the problem.

In order to avoid the diiiiculties described in go-devil operations, the Ring instrument has been provided with various circuit interrupting devices as disclosed in said Smith, Emerson et al. and Kothny patents.

The present invention relates to the provision of means for terminating the recording action at a desired time, being particularly useful for termination of the recording action following the completion of a single record or a series of records. This means constitutes, in one aspect, an improvement over the current interrupting means of the patents referred to above.

As an example of the type of instriunen'ts which may have their operation repeatedly initiated attention is directed to the patent to Williston et al. No. 1,960,038, dated May 22, 1934, disclosing a device constituting means for obtaining a substantially continuous record of the deviation of a bore hole throughout its length and including means for automatically photographing simultaneously the position of a gyroscope, a bubble, and a time piece, from which the deviation of a hole may be readily determined at various points along its length. rThe switching apparatus of the present invention may be employed to enable the drill crew to repeatedly initiate the operation of an instrument such as disclosed by said Williston et al. patent and thereby reduce the loss of lm resulting from the great number of pictures needlessly taken by that instrument while the instrument is being moved from one position to another within the bore hole.

The present switching means and a film moving means such as is disclosed by the Williston et al. patent may be employed in connection with instruments such as are disclosed in the patents to Hewitt No. 2,116,350, dated May 3, 1938, Hewitt et al. No. 2,169,342, dated August 15, 1939, and in the application of Einar T. Young, Serial No. 757,790, filed June 28, 1947. These disclosures show single shot photographic type instruments for recording bore hole survey information. In each instance by the addition ofY a lm moving means controllable by the present switching means these instruments may be modined into multiple shot instruments capable of repeated operation initiated by the drill crew at the surface of the earth.

It will be evident as the description proceeds for the control of electrical, acoustic, radioactive or other logging apparatus or the like.

One of the most desirable methods for controlling operations such as reviewed above is by a centrifugally operated switching means responsive to rotation of the drill stem. However, when the drill bit is raised from the bottom of the drill hole and the drill stem is rotated at any appreciable speed, because of the great length of the free hanging drill stem there is a tendency for the drill stem to whip with a very great possibility of damage or breaking resulting.

It is an object of this invention to provide a switch which will make Contact at relatively low speeds of rotation of the drill stem. v

It is another object of this invention to provide a centrifugal switch which will not make contact as a result of vibration, impact, or inclination such as would result from general handling or passage of the switch within the bore hole, but which will establish an electrical contact when rotated above a predetermined speed.

These and other objects of the invention relating particularly to details of construction and operation will become apparent from the following description, read in conjunction with the accompanying drawings, in which:

Figure 1 is an elevation of the switch assembly partially in section showing iioating pendulums in an outward position such as would result from rotation of the switch assembly;

Figure 2 is a transverse section taken on the plane 2-2 indicated in Figure 1 and showing in particular the pendulum sockets;

Figure 3 is a section taken on theplane 3 3 indicated in Figure l showing the pendulums and the electrical contacts closed thereby, this figure diagramming the electrical connections;

Figure 4 is a diagrammatic representation of an electrical circuit employed when utilizing the present invention to terminate a recording operation;

Figure 5 is a diagrammatic representation of a device employing the present invention to repeatedly initiate recording operations;

Figure 6 is a development of the surface of the timing drum associated with the device shown in Figure 5;

Figure 7 is a fragmentary elevation partly in section showing a modication of the switch assembly;

Figure 8 is a transverse section taken on the plane 8-8 indicated in Figure 7 showing the pendulums and the electrical contacts opened thereby, this figure diagramming the electrical connections; and

Figure 9 is a diagrammatic representation of an electrical circuit employed when utilizing the modification of the invention shown in Figures 7 and 8 to terminate a recording operation.

The centrifugally operated control switch comprises asleeve 4 made of a suitable plastic or other electrical non-conductive material containing auid 6 which is preferably a good grade 0f oil, such as a transformer oil, having high dielectric properties and resistance to oxidation. In this uid are floated pendulums l. The pendulums are desirably formed of aluminum or other light metal tubing sealed at the upper ends by caps includingpointed projecting stems 8 and at the lower ends by silver coated contact caps I8.

The pendulum stems 8 seat by oating insockets 9 of screws I0 which are screwed into tapped bores l2 of a non-conductive member I4. The

member I4 is screwed. yinto position in the u pper end of the sleeve Il .and vthe sleeve is sealed by plug member I6 which is screwed into the sleeve and cementedto prevent oil leakage. The member I6 bears against the member |4 thereby locking the member I4 rigidly in position.

The lower end of thesleeve 4 is plugged by insulatingmember 22 which is screwed into place and cemented to prevent oil leakage. Inmember 22 are mounted contact bars 2U positioned so as to be contacted by lower ends I8 of the pendulums when the pendulums are in outward position.Member 22 also contains slots I9 serving to retain and guide the free ends of the pendulums to insure proper contacting with contact member 2U. The pin |1, mounted in and extending abovemember 22 at the junction of the slots I9, is provided to prevent the pendulums from falling out of their respective slots when the instrument is inclined.

When the control switch is at rest in a vertical position the pendulums. will, by virtue of their weighted lower ends I8, float in vertical positions, grouped together in the center of the liquid chamber and assume positions under the socket screws I8. When the switch is rotated at a suiiicient speed the lower ends of the pendulums will move outward in response to centrifugal force and establish contacts between each of the pairs of contact bars 20 thus completing the circuit from thelead wire 24 throughjumper wires 25 and 26, connecting the lower ends ofbars 20, to lead wire 21. These contacts will be iirm and positive contacts vby virtue of the centrifugal force acting on the pendulums.

It is obvious that inclining the switching assembly or submitting the switch to horizontal impact can not possibly cause all three of the pendulums to :be in outward Vpositions simultaneously. Thus, only by rotating the assembly can a continuous circuit be established between the lead wires. The switch, therefore, can be utilized to establish contact in response to rotation of the drill stem at a speed above the predetermined value and will not establish contact as a result of inclination, impact or vibration as would occur during the lowering of the switch in a drill stem.

Inasmuch as the angle assumed by each of the pendulums is dependent upon the speed of rotation of the switch assembly the value of speed at which switch contact is established, other factors being equal, is dependent upon the length of the pendulums. Thus, reducing the length of the pendulums will cause contact to occur at higher speeds and increasing the length of the pendulums will cause contact to occur at lower speeds. Heretofore in bore hole logging the problem has been to provide reliable contact making means which would operate at sufficiently low speeds of rotation. The present invention will provide desirably reliable contact at speeds below 50 R. P. M. and, by varying the length of the pendulurns, contact can be made to reliably occur at various -reasonably selected and predetermined values. of speed.

The viscosity of the oil in which the pendulums are floated will affect the rate at which the pendulums will move outward, in response to the centrifugal force resulting from rotation, and the rate at which they will move inward, due to the action of gravity alone when the switch is at rest. This rate of motion of thev pendulums. can .be altered by changing the viscosity of the oil; to produce` characteristics of operationv eenerally desirable for any specific operating conditions..

Figure 4 shows the present .invention employed in connection with the Ring type instrument which has been hereinbefore discussed.

There is generally shown at 40 the contact elements of the present invention withlead wire 24 connected to ground. The lead wire 21 is connected throughbattery 42 andconductor 44 tosolenoid coil 48 and throughlead wire 50 to thecommon ground line 52. When this instrument is go-deviled into a drill stem and comes to rest at the bottom thereof current passes from thebattery 54 through the current limiting resistor 55, thependulum member 60, thecontact point 62, andelectrochemical record member 64 to thecommon ground 52 and returns to the battery throughswitch lead wire 66, switch contact lever 61, switch contact point 6.8 and leadWire 18. It

will be noted that the switch contact lever .61 is held nrmly againstcontact point 68 .by the action oflatch member 12 andspring 14.

If the instrument is at rest in one position for sufficient .length of time electrochemical action will cause an indication to be madeon recordingmember 64 under the .contact point 62. After the drill stem has been successively raised and held at rest at the various levels at which records are desirably obtained, the drill stem is then rotated at sufficient speed to cause thecentrifugal contact switch 40 to close completing the circuit through theswitch 40, the wire 21,battery 42, thewire 44, thesolenoid coil 48, thewire 50 andground 52 thereby energizing the solenoid coil 43 and drawing the contact lever 61 against the end of the solenoid core in which position it is locked bylatch member 12 ras a result of the action of thelatch spring 14. Contact is then broken betweencontact point 68 and contact lever 61 and thus thependulum contact point 62 is deenergized and no further records will be made uponrecord member 64. When the instrument is removed from the drill stem,record member 64 is` removed, a new record member is installed and the switch contact lever 61 is reset in prepai ration for the next operation of the instrument.

Figure 5 is a schematic showing of the present invention employed to initiate means for photographing a floating compass element s-uch as is disclosed in the previously mentioned Young application.A There is shown at 40 the contact elements of the present invention. Lead wire 21 is connected throughconductor 81 to abattery 90 the other side of which is grounded to acommon ground 80. Theconductor 81 is connected between thebattery 90 andbrush contact 83 which bears upon the surface of thedrum contactor 92. Thelead wire 86 from the centrifugal switch is connected to brushcontact 82 bearing on thedrum 92.

Themotor 94 is connected throughlead wire 85 to contactbrush 8| and the motor is connected to the common ground throughleadwire 96. Also bearing on the contact drum isbrush member 84 which is connected throughlead wire 88,v lamp 91,conductor 98 and lamp 99 to thecommon ground 80..

Themotor 94 acts through shaft |02, spurv gears |04 and |08, shaft ||0, worm gears ||2 to drive thedrum 92. Mounted on thedrum 92 is a conventional geneva drive guide cam ||4 anddrive pin I|6 which engages thegeneva gear member 8. Mounted on the face of the geneva member |||l is the pulley |.|:9 mounting 7 the belt |20. The belt passes over the pulley |2| which is rigidly xed to film spool |22.

The lm |24 is carried by spools |22, |23, |25 and |26 and passes through film guide |28.

There is suitably disposed at |30 a lens which is located to properly focus the light originating from thelamps 98 and 98 and reflected from compass element |3| upon the film |24 contained within the film guide |28.

The compass element generally shown at |3| comprises glass members |32 and |34 ground to provide an accurate spherical opening |36 in which is located a liquid |38 supporting a float which comprises a body |40 of transparent plastic material. Secured to the body |40 by cement is a second plastic member |42 in the form of a disc provided with a seat for a permanent magnet |44 which is in the form of a ring permanently magnetized and cemented to the member |42. A cap member` |46 is cemented to the member |42 and provides a closure for the air space which provides the necessary buoyance. The surface |48 of member |42 carries engraved markings which may consist of a radial line at its periphery for the indication of azimuth and concentric circles for the measurement of inclination. On the lower' surface of the member |42 there may be engraved a cross or other marking |50 serving when read against the concentric circles to indicate the degree of inclination. The cap |46 may be provided on its interior surface with a white coating to form a definite background for the photographing of black engraved markings. Alternately, the markings may be engraved in white in which case the cap may be coated to provide a black background.

There is shown in Figure 6 the development of the surface of thecontact drum 92. Bearing thereon are the previously mentionedcontact brushes 8|, 82, 83 and 84. When themotor 94 is causing the drum to rotate the drum surface proceeds past the brushes in the direction shown by the arrow |60. The surface of the drum is divided into the conductive area |62 and nonconductive area |63. The position of the brushes shown at Figure 6 is that existing when themotor 64 is inoperative, thecentrifugal switch member 40 is in an open position and the drum contactor is in position to begin a sequence of operation. The operation of the entire instrument can now be reviewed as follows:

When it is desired to operate the recording instrument the drill stem is rotated at a predetermined speed which is known to be suicient to cause the pendulums of the centrifugal switch element to fly outwardly and establish contact through the switch as has been hereinbefore reviewed.

When thecentrifugal contact switch 40 is rotated contact is established through the centrifugal switch member andconductors 21 and 86 between the battery S0 and thebrush 82. Thebrush 82 is bearing on the conductive surface of the drum. Also bearing on the conductive surface of the drum isbrush 8| which is connected to the motor S4. Thus, as soon as contact is established through the centrifugal switch the motor will operate and cause thedrum 82 to rotate.

The drill stem must be rotated to maintam contact through the centrifugal switch during time interval (a) until thedrum 92 has rotated sufciently to bring the conductive surface |62 tobrush member 83 which is connected toconductor 81 directly to thebattery 90. At this time rotation of the drill stem is arrested, the motor proceeds to drive the drum, and during the time interval (b) the pin I6 engages the Geneva drive and draws the lm from the spool |23 through the film holder |28 and on to spool |22 thereby presenting an unexposed portion of film within the film holder |28 in anticipation of the new photograph which is to be made. At the completion of time interval (c)brush 84 is brought to bear upon the conductive surface of the drum causing the lamps 91 and 99 to be illuminated for the period of time (d) during which the position of the compass element is photographed. At the expiration of time interval (d) thebrush member 84 passes from the conductive surface to the non-conductive surface and the lamps are extinguished. At the completion of time interval (e) thecontact brush 83, which is connected throughconductor 81 to the battery 9D, passes from the conductive surface to the non-conduc tive surface of the drum thereby deenergizing the conductor and themotor 94. Thus the rotation of the drum ceases.

It will be observed that time interval (a) during which the drill stem is rotated is relatively short compared to the time interval (c). Thus, ample time is provided for the drill stem and the compass member to come to rest and all parts to be stationary before the photographic record is made.

After the completion of a cycle of operation, the drill stem can be raised any desired extent by the removal of sections at the surface of the ground and, when the instrument is thus raised to a new location in the drill hole at which recordings are to be made, the drill stem is again rotated and the instrument passes through a new sequence of operation. Thus numerous records can be made at various levels in the drill hole without imposing on the drill crew a fixed time schedule presenting intervals during which they must position the drill stem for the next recording and between which they may not rock the instrument without destroying the recording. When employing the present invention the unavoidable delays which may occur at the surface of the ground preventing a drill crew from maintaining such a fixed time schedule do not interfere with the making of the records nor do they jeopardize those records already made. By use of the present invention the instrument will operate only when such operation is initiated by rotation of the drill stem by the drill crew.

Figures 7 and 8 show a modification of the invention in which the pendulums, and the pendulum mountings in the upper portion of thesleeve 4, are identical with those described in connection with Figure 1. However, the contact arrangement mounted in the insulatingmember 22 in the lower portion of the sleeve is modified. The contact bars 202 and 204, mounted in the insulatingmember 22, are located in positions so as not to be contacted by the lower ends of the pendulums |8. Twisted around and soldered to each of thebars 202 is one end of each of theconductive spring wires 206. The other end of each of thewires 206, as a result of its own spring action, makes a positive contact with thebar 204.

The pendulums when moving outwardly in response to centrifugal force, as has been hereinbefore described, will bear against thecontact wires 206 deecting the wires and breaking the contacts between thewires 206 and thebars 204. Thebars 202 and 204 project downwardly through the insulatingmember 22. As diagrammed in Figure 8 thelead wire 208 isconnected' tov each of` the lower ends of the barsv 202- and the lead wire- 210 is ccnnected`4 toeach of the lower ends of thebars 204. It will be evident that inclination, vibration or'impact may eause-one-or possibly twoof theA pendulums to moveoutwardly' and bear upon a Contact wire Bv suilciently tov open the contact between theWire 206 and thebar 204. However, it can be only as a result ofrotas tion of the switchy assembly that all threeof the pendulums` will bear upon the contact wires and cause all three of the contacts' to beopenat the same time. Thus, with the three contacts connected in parallel it can only be as a resultv of rotation that the circuit `betweenl lead wire 208 and 2*!'0v willl be brok-en. K

This modification of the switch assembly may be employed in connection with the above mentioned' Ring instrument in the circuit shown in Figure 9 in which there is generally'shown at 2 |-2 the contact arrangements of the modification cf the'invention shown in Figures '7' and. 8A with thelead wire 2| 0 connected to thecommon ground wire 222 and the lead wire 208'connected through thebattery 214, and through lead-wire 2|5 to the contact ZIB. Thecontact arm 2|.8 is connected through thesolenoid coilv 220 to the common ground" 222.

One side of-the battery'224 is connecte-d through lead wire 2-28` to thecontact point 230, and the contact arm 23?. is connected throughlead wire 234 to thecommon ground 222. The other side ofthefbattery 224 is connected throughthecurrent limiting resistor 56; thependulum member 60, the contact point 62', and anelectrochemical record member 64 to the common ground' 222'.

When this modiiication` of the instrument is prepared for go-devilling intothe drillv stem thepush button 236 is manually depressedclosing the contact arm. 2i|8 against contact point 21.6 thus initiating a current ow vfromthe battery 2l4 throughy the lead'wire 215, the contact ZF6, con*- tact arm 218',armature coil 220common ground 222, and the centrifugal switch. assembly2ll2 back to thebattery 214; The magnetic eld inducedy bythe current passing throughthefarmature coil 220 will hold the Contact arm. 218' against the end of thearmature and will also pull'inA thecontact arm 232 against the otherv end' of the' arma-- ture thereby establishing contact between thecontact point 230 and thecontact arm 232.

The closing ofcontactv 230 will permit a current to fiow from the battery224 through' the current limitingresistor 56, the lpendulum member 6'0,contact point 62,electrochemical record memberv 64, common ground 222', lead Wire; 234,contact arm 232,Contact point 230 and the lead wire 22-3 back to thebattery 224.

With the recording apparatus thus energizedv the instrument is go-deviled intol a drill stem.y After a succession of records havefbeen' made, as has been hereinbefore described,` and it isxdesired to interrupt the record making process and retrieve the record element, the drill stem will'beirotated at a sufficienti speed toE cause. the pendulums to move outwardly generally simulta.

neously and to break the circuit betweenlead wires 208 and. 210. Thusy the current iiowing from the battery 2M through thearmature coil 220 will bek interrupted. The field through the armature core will collapse and the tension springs 238 and 240 will open the contact arms 213% and232ai and will hold. the contact arms open against vibration, inclination or impact, thus permanently interrupting both the current ow through thearmature coil 220 and the current flow throughthecontact point 62 and the electrochemical recordmember B4' until such time as the instrument is retracted and thepush button 236 is manually depressedreestablishing the current flow from the-battery 2 I4 through thearmature coil 220 recreating the magnetic field in the armature core.

It will be evident that numerous Variations, such as anchoring the pendulums at their lower ends and allowing the upper ends to respond to centrifugal force, employing various modications of the contact arrangement, and the like, may be made in details of the embodiment of the invention without departing from the scope thereof as dened in the following claims.

Wha-t I claim andv desire to protect by Letters Patent is:

l. A switch assembly for initiating electrical contact'in a bore hole measuring apparatus comprising a chamber containing a fluid medium, floating contact means in said medium and stationary contact means in said medium, said oating contact means contacting said stationary contact means in response to the centrifugal force acting on said floating contact means when the switch assembly is rotated.

2. A switch assembly for initiating electrical contact in a bore hole measuring apparatus comprising a chamber containing a fluid medium, floating contact means in said medium mounted inwardly within said chamber and stationary contact means in said medium mounted outwardly within said chamber, said floating contact means moving outwardly and contacting-said stationary contact means in response to the centrifugal force acting on said floating means when the switch assembly is rotated at a rate inexcess of a predetermined rate of rotation.

3. A switch assembly for initiating electrical contact in bore hole measuring apparatus comprising a chamber containing a fluid medium, a plurality of pendulum members floating in said medium, and stationary contact members mounted outwardly of one end of each of said pendulum members, the ends of'each of said pendulums contactingv the! contact members in respouse` to the centrifugal force acting on the pen'- dulums when the switch assembly is rotated.

4. Apparatus for controlling the operation of a borehole measuring instrumentr including an electrically operated contact means, means providing a source ofv electric current, and a centrifugally'op'erated switching means, said means connected and arranged to provide a flow of current from said current sourcev through said electrically operated contact means whenV said cen'- trifugally operated switching means is madek conductive as a result of rotation thereof.

5. Apparatus for controlling the operation of a'bore hole measuring instrument including an electrically operated contact means, means pro viding a source of electric current, and a centrifugally operated switching means comprising..

a chamber containing a fluid andy contact members iioating in said iiuid, said means. connected and arranged to provide a ilow of' current from said' current source through said electrically operated contact means` whenw said centrifugally operated switching means ismade conductive as a result of rotation thereof.

6. Apparatus for controlling the' operation of a bore hole measuring instrument including an electrically operated contact means, means providing a source of electric current, and a centrifugally operated switching means comprising a chamber containing a fluid, floating contact members, and stationary contact members, said means connected and arranged to provide a flow of current from said current source through said electrically operated contact means when said centrifugally operated switching means is made conductive as a result of contact being established between the floating contact member and the stationary contact members when the switch assembly is rotated.

7. A switch assembly for interrupting an electrical circuit in a bore hole measuring apparatus comprising a chamber containing a fluid medium, floating means in said medium and contact means mounted in said chamber, said floating means bearing against said contact means in response to the centrifugal force acting on said floating means when the switch assembly is rotated and opening the contact means.

8. A switch assembly for interrupting an electrical circuit in a bore hole measuring apparatus comprising a chamber containing a fluid medium, floating means in said medium mounted inwardly within said chamber and contact means mounted outwardly within said chamber, said floating means moving outwardly and bearing against said contact means in response to centrifugal force acting on said floating means when the switch assembly is rotated at a rate in excess of predetermined rate of rotation and opening the contact means.

9. A switch assembly for interrupting an electrical circuit in a bore hole measuring apparatus comprising a chamber containing a fluid medium, a plurality of pendulum members floating in said medium mounted inwardly within said chamber and contact means mounted outwardly of each of said pendulum members within said chamber, the ends of each of said pendulums bearing against said contact means in response to the centrifugal force acting on said floating means when the switch assembly is rotated at a rate in excess of a predetermined rate of rotation and opening the contact means.

l0. Apparatus for controlling the operation of a bore hole measuring instrument including an electrically operated contact means, means providing a source of electric current, and a centrifugally operated switching means comprising a chamber containing a fluid and members floating individually in said fluid, said means connected and arranged to provide a flow of current from said current source through said electrically operated contact means when said centrifugally operated switching means is at rest, and interrupting the flow of current when the switch is made non-conductive as a result of rotation thereof.

ll. Apparatus for controlling the operation of a bore hole measuring instrument including an electrically operated contact means, means providing a source of electric current, and a centrifugally operated switching means comprising achamber containing a fluid, floating members, and contact members, said means connected and arranged to provide a flow of current from said current source through said electrically operated contact means when said centrifugally operated switching means is at rest, and interrupting the flow of current when the sWzQh,

rotated and made non-conductive by the floating members acting upon the contact members in response to centrifugal force acting upon said floating members when the switch assembly is rotated.

12. A switch assembly for controlling an electrical circuit in a bore hole measuring apparatus comprising a chamber containing a fluid medium, floating means in said medium and contact means mounted in said chamber, said floating means bearing against said contact means and effecting control of said contact means in response to the centrifugal force acting on said floating means when the switch assembly is rotated.

13. A' switch assembly for controlling an electrical circuit in a bore hole measuring apparatus comprising a chamber containing a fluid medium, floating means in said medium mounted inwardly within said chamber and contact means mounted outwardly within said chamber, said floating means moving outwardly and bearing against said contact means and effecting control of said contact means in response to the centrifugal force acting on said floating means when the switch assembly is rotated.

14. A switch assembly for controlling an electrical circuit in a bore hole measuring apparatus comprising a chamber containing a fluid medium, a plurality of pendulum members floating in said medium mounted inwardly within said chamber and contact means mounted outwardly of each of said pendulum members within said chamber, the ends of each of said pendulums bearing against said contact means and effecting control of said contact means in response to the centrifugal force acting on said floating means when the switch assembly is rotated.

15. Apparatus for controlling the operation of a bore hole measuring instrument including an electrically operated contact means, means providing a source of electric current, and a centrifugally operated switching means comprising a chamber containing a fluid and members floating individually in said fluid, said means connected and arranged to control the flow of curd rent from said current source through said electrically operated contact means when said centrifugally operated switching means is made operative as a result of rotation thereof.

16. Apparatus for controlling the operation of a bore hole measuring instrument including an electrically operated contact means, means providing a source of electric current, and a centrifugally operated switching means comprising a chamber containing a fluid, members floating individually in said fluid, and contact members. said means connected and arranged to control the flow of current from said current source through said electrically operated contact means when said centrifugally operated switching means is made operative as a result of contact being established between the floating members and the contact members when the switch assembly is rotated.

GILBERT JAMES BUTIERWORTH.

REFERENCES CITED UNITED STATES PATENTS Name Date Kohl T?, Nov. 16, 1948 Number

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