US3916722A

US3916722A - Treadle operated control

Info

Publication number: US3916722A
Application number: US515592A
Authority: US
Inventors: Donald F Grobe
Original assignee: Square D Co
Current assignee: Schneider Electric USA Inc
Priority date: 1974-10-17
Filing date: 1974-10-17
Publication date: 1975-11-04
Anticipated expiration: 1992-11-04
Also published as: FR2288349A1; IT1047397B; AU8496775A; DE2546404C3; AU473633B2; DE2546404B2; ZA755859B; FR2288349B1; CA1026211A; DE2546404A1; GB1527142A

Abstract

A foot control of the treadle operated type has a latching mechanism which normally latches the treadle in an inoperative position and which must be released before the treadle can be moved to an operative position. The latch mechanism includes a latch plate which, as the latch mechanism is being set to latch the treadle in its inoperative position, is moved to a restricting position wherein it restricts access to the treadle by the foot of an operator or by a foreign object. The latch plate is yieldably constrained to restricting position after the latch mechanism is set, and must be moved out of its restricting position to re-establish free access to the treadle and release the latch mechanism. The direction in which the latch plate must be moved for moving it out of its restricting position is opposite from the direction in which the treadle must be moved to reach its operative position.

Description

i United States Patent [191 Grobe [4 1 Nov. 4, 1975 [73] Assignee: Square D Company, Park Ridge, 111.

221 Filed: Oct. 17, 1974 21 Appl. No.: 515,592

[52] US. Cl. 74/512; 74/560; 192/129 A; ZOO/86.5 [51] Int. Cl. G05G 1/ 14 [58] Field of Search 74/512, 560, 561; 100/53;

192/129 A, 129 B, 129 R; ZOO/86.5; 292/210 Primary Examiner-Samuel Scott Assistant ExaminerF. D. Shoemaker Attorney, Agent, or Firm-John Harrow Leonard [57] ABSTRACT A foot control of the treadle operated type has a latching mechanism which normally latches the treadle in an inoperative position and which must be released before the treadle can be moved to an operative position. The latch mechanism includes a latch plate which, as the latch mechanism is being set to latch the treadle in its inoperative position, is moved to a restricting position wherein it restricts access to the treadle by the foot of an operator or by a foreign object. The latch plate is yieldably constrained to restricting position after the latch mechanism is set, and must be moved out of its restricting position to reestablish free access to the treadle and release the latch mechanism. The direction in which the latch plate must be moved for moving it out of its restricting position is opposite from the direction in which the treadle must be moved to reach its operative position.

8 Claims, 4 Drawing Figures US. Patent Nov. 4, 1975 .1 2 w I K fw a FIG

TREADLE OPERATED CONTROL BACKGROUND OF INVENTION 1. Field of Invention Treadle operated controls for switches, and other mechanisms.

2. Prior Art Treadle operated foot controls are commonly used for operating control mechanisms, such as valves and electric switches which, in turn, control various type of mechanisms, such as shears, bending and forming presses, power shovels, locomotive equipment, and the like. Such foot controls usually are disposed on the floor or on a platform adjacent the mechanism to be controlled, in a position convenient for actuation by the foot of the operator. However, in such positions, the control treadle, though shielded by a guard, is easily accessible for accidental movement to its active position, as by being stepped on inadvertently, or by being struck by a falling or moving object. Again, if the control is placed on a level or platform above the floor and falls therefrom, the treadle may be caused to operate by direct impacts thereon or by components of inertial forces imposed upon the movable parts of the control as a result of its striking the ground or floor.

Such dangers are unacceptable under various industrial or other accepted codes and regulations and attempts have been made to eliminate them. For example, as disclosed in U.S. Pat. No. 3,759,115, of Sept. 18, 1073, a treadle operated control is disclosed in which the treadle is shielded by a guard having a forwardly open end into which the toe of the operators shoe must be inserted preparatory to operation of the treadle by the operator's foot. The treadle thereof is held in inactive position by a latch mechanism having a toe plate. The toe plate is positioned at the inner end of the tread portion of the treadle and is arranged so that it must be engaged and moved inwardly of the guard by the toe of the operators shoe as the operators foot is moved into final manipulating position on the tread of the treadle. The prior structure has a disadvantage in that the toe plate does not restrict access to the treadle. Further the toe plate is arranged so that it can be swung inwardly and downwardly of the guard endwise of the treadle for releasing the latch mechanism. Consequently, it is readily accessible to any object projected inwardly, endwise of the treadle, through the open end of the guard. Such an object, if of sufficient weight and impelled by moderate force, such as an accidentally dropped steel bar, can move the toe plate to release the latch and concurrently depress the treadle to operative position. If such a treadle operable control is dropped bodily downwardly, it is possible for portions of its base or of its guard to strike the floor at an angle relative to its working parts such that a resultant unidirectional inertial force will impose on the parts components of force which are capable of moving the toe plate inwardly to its release position and, concurrently, the treadle into its operative position, thereby causing an accidental operation of the controlled machine or equipment.

valves, electric SUMMARY In the present invention, the control has a treadle, an open end treadle guard, and a plate for latch release, as broadly disclosed in the prior art. However, the treadle and latch plate are arranged so that the latch plate restricts access to the treadle through the open front end of the guard and the latch plate must be moved both out of its restricting position at the entrance to the guard and into a latch releasing position by movement in a direction in which the treadle must be moved to reach its operative position. An operator cannot inadvertently trip the treadle. Instead, he must deliberately insert his foot, toe foremost, between the latch plate and treadle, force the latch plate upwardly by the top of his shoe toe sufficiently to release the latch before the sole of his shoe can be moved onto the treadle, and then, while holding the latch plate in this latch releasing position and his foot in operating position, depress the treadle to its active position with his foot. The directions and sequence of movements of the latch plate and treadle, being opposite from each other, are such that any unidirectional inertial or other forces having a component directed so as to operate the treadle must also have an oppositely directed component for operating the latch plate to release the latch mechanism. These force components must be very substantial. As a result, accidental operation of the treadle is greatly reduced.

Various other and specific objects and advantages of the invention will become apparent from the following description in which reference is made to the drawings illustrating a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a treadle operated control embodying a preferred form of the invention, part of the guard and latch plate of the control being cut away for clearness in illustration;

FIG. 2 is a front elevation of the foot control illustrated in FIG. 1;

FIG. 3 is a vertical longitudinal sectional view of the control and is taken on the line 3-3 in FIG. 2 and shows the treadle latched in inactive position; and

FIG. 4 is a longitudinal sectional view, similar to FIG. 3, showing the latch released from the treadle, and the treadle depressed into its operative position.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, the control is shown for purposes of illustration as operating an electric switch of a known type, indicated generally at l, which may be such as disclosed in U.S. Pat. No. 3,250,874, issued May 10, 1966. The switch 1 comprises a stationary contact 2 and a complementary movable contact 3. The contact 3 is mounted on a suitable carrier 4 which, in turn, is mounted on a shaft 5 for swinging movement from an open position, as illustrated in FIG. 3, to a closed position, as illustrated in FIG. 4. The shaft 5 is mounted on the base 6. The switch is enclosed in a compartment 7. A foot treadle 8 is mounted on the base and is operative upon depression to move the switch from normally open position to its closed position. This structure so far described is conventional and well known in the art.

The base 6 of the control is usually heavy cast metal. It is designed to rest on a horizontal supporting surface and support the treadle 8 with its tread 9 facing upwardly. A guard 11 is mounted on the base 6 and has a partition wall 12 which cooperates with a wall 13 on the base to provide the compartment 7 for the switch. For supporting the treadle for rocking movement to operative and inactive positions, the treadle is provided with arms 14 which extend rearwardly of the treadle from its tread 9 and which are pivotally mounted at their rearmost ends on the shaft 5. A suitable return spring 15 is interposed between the base 6 and the treadle 8 and biases the treadle upwardly about the axis of the shaft 5 to an inactive position, as illustrated in FIG. 3, in which the switch 1 is open.

In order to prevent accidental depression of the treadle a latch mechanism, indicated generally at 19, is provided. This mechanism includes cars 16 rigid with, and extending laterally outwardly from, the arms 14, respectively, at a location thereon in spaced relation to the shaft 5. The under faces of the ears 16 provide latching shoulders 17.

Mounted in the side walls of the guard 11 is a shaft 20, arranged forwardly from the shaft 5 and in spaced relation above the base 6 a much greater distance that is the shaft 5. The latch includes laterally spaced arms 21 which are pivotally mounted on the shaft 20 so as to depend from the pivotal axis thereof. At their lower ends, the arms 21 have notches 22, respectively, which open rearwardly of the treadle and are adapted to re ceive the ears 16 when the treadle is in raised inactive position and the latch mechanism 19 is in its lowermost or active position. The notches 22 have upwardly facing bottom walls 23 cooperable with the bottom walls 17 of the ears 16 for latching the treadle 8 against downward movement from the inactive position illustrated in FIG. 3 toward the active position illustrated in FIG. 4.

Further, the latch mechanism includes a latch releasing member 24 in the form of a plate which is integral with the arms 21 and which is disposed at the opposite side of the shaft 20 from the notches 22. The member 24 has a downwardly convex foot engaging portion 25 which, in the normal latching position of the latch mechanism, is spaced slightly above the level of the upper face of the tread 9 of the treadle 8, when the treadle is in its inactive position, and restricts access to the treadle through the open front of the guard 11. The weight of the member 24 is such that when the base 6 is horizontal, the member 24 and the arms 21 rock about the shaft 20 in a counterclockwise direction in FIG. 3, to active latching position wherein, with the treadle raised to inactive position, the ears 16 are engaged in the notches 22 of the arms 21, thus latching the treadle against depression.

If desired, a biasing spring 26 may be connected to the arms 21 and to a wall of the guard 11 so as to more positively bias the arms 21 to latching position.

The guard 11 has a top forward wall 27 and depending side walls 28, the top wall being in spaced relation above the treadle 8 and member 24 in all positions of the treadle 8 and member 24, so as to prevent accidental depression of the treadle 8 by a downward bodily movement of the foot of the operator or by a falling object. The side walls 28 prevent access to the treadle 8 laterally.

The forward marginal portion 25 of the member 24 may extend forwardly and downwardly so that its outer end is outwardly beyond the forward end of the treadle 8 and the forward edge of the

walls

27 and 28. Thus it can be readily seen and engaged on its under side by the toe of an operators foot and swung upwardly thereby as the foot of the operator is moved inwardly of the guard 11 endwise of the treadle 8 to a position for operating engagement on the treadle 3. Though the portion 25 of the member 24 extends outwardly beyond the guard 11, forces imposed thereon as a result of objects dropped on the portion 25 or due to accidental stepping on the portion 25 by an operator, are applied thereto downwardly and merely bias the latch mechanism more firmly into latching position.

Here it must be noted that, due to the positioning of the

shafts

5 and 20, the directions in which the treadle 8 and member 24 must be swung about their respective pivotal axes for moving the latch mechanism to release position and the treadle 8 to active position, are directly opposite from each other. It is necessary to swing the treadle 8 downwardly in the horizontal position of the base 6 and the member 24 upwardly, As a result it does not matter in which position the control, if dropped, strikes the floor, the resultant inertial force will be inoperative to cause the treadle to move to its active position, because the member 24 and the treadle 8 must be swung in opposite directions concurrently about their respective pivotal axes in order to release the latch mechanism and move the treadle to active position. It should be noted that any inertial force directed in a direction to move the treadle 8 toward its active position will move the member 24 in the same direction, and therefore move the notches 22 more firmly into latching position relative to the ears 16. Any inertial force that can be directed to move the member 24 in a direction to release the notches 22 from the ears 16 will move or bias the treadle 8 to inactive position.

For example, assume the control as illustrated in FIG. 3 is dropped downwardly and should strike the floor on the rear end, the right hand end in FIG. 3. The inertial force component on the treadle 8 would be small and clockwise, tending to move the treadle 8 to inactive position, and the inertial force components on the member 24 would be large and counterclockwise, tending to move the latch mechanism more firmly into latching position. If, on the other hand, the control should strike on what is the upper right hand corner in FIG. 3, the inertial forces on the member 24 would tend to release the latch mechanism but at the same time be counteracted to a large extent by the inertia of the arms 21. Concurrently the inertial forces on the treadle it would bias the treadle 8 to inactive position. If the lower right hand corner of the control, as viewed in FIG. 3, should strike the floor, there would be a substantial component of inertial force on the treadle 8 which would bias the treadle to active position, but concurrently, a very large component of force on the arms 21 and the member 24 which would bias the arms and plate counterclockwise and thus bias the latch mechanism even more firmly into latching position. If the upper left hand corner, in FIG. 3, should strike the floor, though the inertial forces on the member 24 and arms 21 would tend to release the notches 22 from the cars 16, coexisting inertial forces on the treadle would tend to move it to inactive position. If the lower left hand corner, in FIG. 3, should strike the floor, the inertial forces on the treadle 8 would tend to move it to active position, but at the same time the inertial forces on the member 24 would bias the latch mechanism more firmly into latching position. If the control should strike the floor in completely inverted position, the inertial forces on the member would tend to unlatch the latch mechanism for an instant, but at the same time those on the treadle 8 would bias it to inactive position. If the control should strike the floor in normal operating position, though the inertial forces would tend to swing the treadle downwardly to active position, at the same time the inertial forces of the member 24 would bias the latch mechanism more firmly into a latching position.

It is apparent, therefore, that a most unusual set of circumstances would have to occur simultaneously in order to release the latch mechanism and depress the treadle. It would have to be an action so closely approximating the deliberate manipulation of the toe of the operator for releasing and operating the treadle that its occurrence by happenstance would be very remote.

Having thus described my invention, I claim:

1. A foot control including a base;

a treadle mounted on the base for movement in one direction to an active position and in an opposite direction to an inactive position;

means biasing the treadle to, and yieldably holding it in, said inactive position;

a movable latch mechanism carried by the base and normally held in a latching position in which it latches the treadle in said inactive position, and movable from latching position to a release position in which it releases the treadle for movement to said active position;

said latch mechanism including a movable latch releasing member which is in a normal position when the latch mechanism is in latching position, and which is movable in a predetermined direction from its said normal position to a release position in which it moves the latch mechanism into its said release position;

characterized in that said latch releasing member and treadle are mounted in relation to each other such that said predetermined direction of movement of the latch releasing member is generally opposite to said one direction of movement of the treadle.

2. A foot control according to claim 1 wherein ,the latch releasing member is positioned relative to the treadle so that when the treadle is in its inactive position and concurrently the latch releasing member is in its normal position, the latch releasing member restricts access to the treadle along a predetermined path, and when the latch releasing member is in its release position it is out of its restricting position relative to said path.

3. A foot control according to claim 2 wherein the latch releasing member and treadle are arranged so that when the base is horizontal, said one direction of movement of the treadle is downwardly, and said predetermined direction of movement of the latch release member is upwardly;

the latch release member, in its normal position, is

above the level of the treadle, is accessible at its underside to the top of a foot of an operator for movement upwardly to its latch releasing position thereby, and is positioned so that it must be engaged and moved upwardly by the operators foot, as the foot is moved generally horizontally along said predetermined path into position for engagement with the treadle, before the foot can engage the tread of the treadle.

4. A foot control according to claim 3 wherein a first pivot means is carried by the base'and'supports the treadle for rocking movement about an axis extending horizontally and transverselyof the base;

the treadle extends in a direction forwardly of the base from said axis;

a second pivot means carried by the base supports the latching releasing member for rocking movement about an axis parallel to that of the first pivot means; and

said second pivot means is arranged so? that its axis is forwardly of the base from, and at a level above, the axis of the first pivot means, in the horizontal position of the base.

5. A foot control according to claim 3 wherein a guard is carried by the base and has a top wall in overhanging spaced relation to the treadle and member;

said guard extends, endwise, in a direction forwardly and rearwardly of the treadle and projects forwardly beyond the forward end of the treadle, and is open at its forward end to afford access thereinto and to the treadle by the foot of the operator; and

said member has a foot engageable portion disposed forwardly of the forward end of the treadle.

6. A foot control according to claim 5 wherein said foot engageable portion is a forward margin of the member and is disposed, in a direction forwardly of the treadle, beyond the forward end of the guard.

7. A foot control according to claim 6 wherein said foward margin is curvilinear and convex downwardly.

8. A foot control including i a base;

a treadle mounted on the base for movement-in one direction to an active position and in an opposite direction to an inactive position;

means biasing the treadle to, and yieldably holding it in its said inactive position;

a movable member carried by the base and movable in one direction into a normal position in which it restricts access to the treadle, and in a predetermined direction from its normal position to an inactive position in which it is,out of access restricting relation to the treadle; and

means biasing the member to, and yieldably holding it in, its said normal position;

characterized in that said member and treadle are mounted on the base for movement in relation to each other so that said predetermined direction of movement of the member is generally opposite to said one direction of movement of the treadle.

Claims

1. A foot control including a base; a treadle mounted On the base for movement in one direction to an active position and in an opposite direction to an inactive position; means biasing the treadle to, and yieldably holding it in, said inactive position; a movable latch mechanism carried by the base and normally held in a latching position in which it latches the treadle in said inactive position, and movable from latching position to a release position in which it releases the treadle for movement to said active position; said latch mechanism including a movable latch releasing member which is in a normal position when the latch mechanism is in latching position, and which is movable in a predetermined direction from its said normal position to a release position in which it moves the latch mechanism into its said release position; characterized in that said latch releasing member and treadle are mounted in relation to each other such that said predetermined direction of movement of the latch releasing member is generally opposite to said one direction of movement of the treadle.

2. A foot control according to claim 1 wherein the latch releasing member is positioned relative to the treadle so that when the treadle is in its inactive position and concurrently the latch releasing member is in its normal position, the latch releasing member restricts access to the treadle along a predetermined path, and when the latch releasing member is in its release position it is out of its restricting position relative to said path.

3. A foot control according to claim 2 wherein the latch releasing member and treadle are arranged so that when the base is horizontal, said one direction of movement of the treadle is downwardly, and said predetermined direction of movement of the latch release member is upwardly; the latch release member, in its normal position, is above the level of the treadle, is accessible at its underside to the top of a foot of an operator for movement upwardly to its latch releasing position thereby, and is positioned so that it must be engaged and moved upwardly by the operator''s foot, as the foot is moved generally horizontally along said predetermined path into position for engagement with the treadle, before the foot can engage the tread of the treadle.

4. A foot control according to claim 3 wherein a first pivot means is carried by the base and supports the treadle for rocking movement about an axis extending horizontally and transversely of the base; the treadle extends in a direction forwardly of the base from said axis; a second pivot means carried by the base supports the latching releasing member for rocking movement about an axis parallel to that of the first pivot means; and said second pivot means is arranged so that its axis is forwardly of the base from, and at a level above, the axis of the first pivot means, in the horizontal position of the base.

5. A foot control according to claim 3 wherein a guard is carried by the base and has a top wall in overhanging spaced relation to the treadle and member; said guard extends, endwise, in a direction forwardly and rearwardly of the treadle and projects forwardly beyond the forward end of the treadle, and is open at its forward end to afford access thereinto and to the treadle by the foot of the operator; and said member has a foot engageable portion disposed forwardly of the forward end of the treadle.

8. A foot control including a base; a treadle mounted on the base for movement in one direction to an active position and in an opposite direction to an inactive position; means biasing the treadle to, and yieldably holding it in, its said inactive position; a movable mEmber carried by the base and movable in one direction into a normal position in which it restricts access to the treadle, and in a predetermined direction from its normal position to an inactive position in which it is out of access restricting relation to the treadle; and means biasing the member to, and yieldably holding it in, its said normal position; characterized in that said member and treadle are mounted on the base for movement in relation to each other so that said predetermined direction of movement of the member is generally opposite to said one direction of movement of the treadle.