US2910564A

US2910564A - Limit switch

Info

Publication number: US2910564A
Application number: US763762A
Authority: US
Inventors: Robert C Mcbroom
Original assignee: Individual
Current assignee: Individual
Priority date: 1958-09-26
Filing date: 1958-09-26
Publication date: 1959-10-27
Anticipated expiration: 1976-10-27

Description

Oct. 27, 1959 R. c. MCBROOM LIMIT SWITCH Filed Sept. 26, 1958 INVENTOR. R ulnar]; C.ME1ruum BY a J ,p flzwammm United States Patent Q LIMIT swrrcn Robert C. McBroom, Lynn, Mass., assignor, by mesne assignments, to the United States of America as represented by the Secretary of the Army Application September 26, 1958, Serial No. 763,762

4 Claims. (Cl. 200153) This invention relates to a limit switch and more particularly a limit switch used to provide a take-off indication for a guided missile.

For launching a guided missile from a ground plat form it is necessary to provide an electric signal to indicate the exact time of take-ofi of the missile from the launcher. The signal is provided by a limit type take ofi switch mounted on the ground platform with the actuator of the switch contacting the base of the missile. While the missile remains on the platform, the actuator is held in a depressed position to hold the switch open. As the missile rises the actuator is released to allow the switch to close. While the missile remains on the platform it is necessary to run complete electrical system tests and one of the tests necessary is to ascertain that the take-oft switch is functioning. Means are, therefore, provided to operate the switch to close same for test purposes while the missile is in firing position.

An object of the invention is to provide a limit switch for guided missile launching provided with means to test the switch before firing.

A further object of the invention is to provide a spring biased limit switch held in open position by a missile on a launching platform and means to move the switch before the missile is launched to check the operation thereof.

Yet another object is to mount a limit switch on a pivoted plate so that the switch may be swung clear of the switch operator.

In the drawing:

Figure 1 is a plan view of the limit switch of the invention and being partly broken away to show the interior mechanism, and

Figure 2 is a cross-sectional view of the limit switch taken on the line 2--2 of Figure 1.

Referring to the drawing the line A represents one side of a track or way on a guided missile launching platform. The missile when in launching position would be disposed above the line A in Figure l and would be launched to the right or left.

The limit switch which forms the subject matter of this invention is indicated in its entirety by reference character 1 and may be rigidly attached to the launching platform in any suitable manner. The casing of the switch is indicated at 2 and is provided with a cover plate 3 attached thereto by means of bolts 4. Between the cover plate and casing is provided a sealing member 5 to provide weather-tightness for the switch.

The switch casing is provided with opposite end walls 6 and 7 and these end walls are provided with aligned apertures 8 and 9 for the reception of operator pin 10. The pin 10 carries at one end an adjustable head 11 adapted to contact a missile held in position for firing and at the other end a nut 12 to limit upward movement of the pin with respect to the casing. Intermediate its ends the actuator pin is provided with a shoulder 13 and a spring 14 surrounds the pin and reacts between the casing and shoulder to bias the pin in an upward direc- Fee tion. The pin is further provided with a cam surface 15 and cylindrical portion 28, the function of which will presently appear.

Mounted within the switch casing is a bolt 16 to which is pivoted'a plate 17 having an arcuate slot in the upper portion thereof. Also mounted within the casing is a bolt or stud 19 which extends through the slot in the plate to limit the pivoting movement of the plate. The plate 17 also carries an upstanding apertured flange 20. The lower wall 7 of the casing is provided with a second aperture 21 for the reception of test actuator pin 22 which is connected to flange 20 at one end and has a hand manipulable knob 23 at its other end disposed outside of the switch casing. A coil spring 24 is disposed between the casing and flange 20 to bias the pivoted plate 17 to the right to the extent permitted by slot 18.

The plate 17 has rigidly mounted thereon the box 25 which carries the contact elements of the switch (not shown). The contact elements are operated by operator button 26 which is biased to the right in Figure 1 by means of spring 27 to close the contacts and which may be moved to the left by cam surface 15 on pin 10 to open the contacts.

In operation a missile is placed in the launching way and the pin 10 is depressed thereby such that the cam 15 actuates the operator button 26 to open the switch contacts. The long cylindrical portion 28 of the pin permits overtravel and allows for different positions of the mis sile on the launching platform while still. operating the limit switch. When the missile is launched the pin 10 will be forced upwardly by spring 14 thus allowing the.

switch is for an operator to grasp knob 23 and pull downwardly. This pivots the entire plate 17 about bolt 16 away from the pin 10 and allows the spring 27 to move the button 26 to the right to close the switch contacts. When the operator releases the knob 23 the spring 24 will return the plate to the right and the button into contact with pin 10 to open the switch contacts. Thus, the switch contacts cannot be accidentally left closed after test with the missile in position for launching.

It will be apparent that the embodiment shown is only exemplary and that various modifications can be made in construction and arrangement within the scope of the invention as defined by the appended claims.

I claim:

1. A limit switch comprising a casing, a contact carrying plate pivotally mounted in said casing and having an operator button, biasing means to urge said operator button in one direction, an operator slidably mounted in said casing adjacent said button and adapted to actuate said button against the action of said biasing means, a test actuator connected to said plate and being hand manipulable to swing said plate and operator button away from said operator to allow said operator button to move to the biased position regardless of the position of said operator.

2. A limit switch adapted to be mounted on a missile launching device comprising a casing, an operator slidably mounted in and extending exteriorly of said casing, a spring surrounding and urging said operator in an outward direction, said operator being adapted to be depressed against the action of said spring by a missile in position for launching, an operator button mounted in said casing and biased into contact with said operator and means to move said operator button out of contact with saidoperator to -permit test of said switch while the missile is in position. 7

3. A limit switch comprising a casing having opposed end walls with aligned apertures therein, a plate pivoted in said .casing and having a contact operating-button mounted thereon,-a spring biasing said operating button outwardly of said plate, an operator slidable in the aligned aperturesof said casing and being spring biased in one direction, a cam surface onsaid operator adapted to depress said operatingbutton when said operator is moved against its spring bias, a test actuator connected to said plate and operable to swing said plate and operating button clear of said operator-and a spring surrounding said test actuator and reacting between said plate and casing to urge said operating button'into contact with said operator.

'4. A limit switch comprising a casing having end and.

' side walls, said casing having aligned apertures in the opposed end walls thereof and a third aperture in one of said walls, a pivot pin mounted within said casing, a plate in said casing pivoted on said pivot pin and having a contact operating button thereon, a spring biasing said operating button outwardly of said plate, an operator slidable in the aligned apertures of said casing and being spring biased in one direction, a cam surface on said operator adapted to depress said operating button when said operator is moved against said spring bias, a test actuator connected to said. plate. and extending exteriorly of said casing through said third aperture, said test actuator being manually manipulable to swing said plate References Cited in the file of this patent UNITED STATES PATENTS Crew Sept. 12, 1944 Framhein Apr.;13,.'1954