US2296760A - Step-by-step switch - Google Patents

Description

p 1942- t G. J. BARRY 2,296,760

STEP BY STEP SWITCH I Filed June 3, 1939 5 Sheets-Sheet l p 1942- G. J. BARRY 2,296,760

' STEP BY STEP SWITCH Filed June 3, 1939 5 Sheets-Sheet 2 iizaerdr ziq p 1942- G. J. BARRY 2,296,760

STEP BY STEP SWITCH I Filed June 3/ 1939 5 Sheets-Sheet 3 he TcZ r- (fera/aJjarry Sept. 22, 1942. G A Y I 2,296,760

I STEP BY STEP SWITCH Filed June 3, 1939 5 Sheets-Sheet P 1942- Q a. J. BARRY 2,296,760

STEP BY STEP SWITCH Filed June 5, 1959 5 Sheets-Sheet 5 Irwernr Patented Sept. 22, 1942 STEP-BY-STEP SWITCH Gerald J. Barry, Philadelphia, Pa., asslgnor, by

mesne assignments, to Philco Radio and Television Corporation, Philadelphia, Pa., a cor-- poration of Delaware Application June 3, 1939, Serial No. 271,273 7 plaims. (Cl. 74-155) This invention relates to positioning devices for actuating an element or elements to certain selectable positions and, more particularly, the invention relates to a novel step-by-step mechanism adapted to respond to control impulses and to position the controlled elements in a novel manner.

In the copending application of Milton L. Thompson, Serial No. 220,356, filed July 20, 1938,

and the copending application of David Grimes 10 other words, the first shaft has a certain operatand Elmer 0. Thompson, Serial No; 220,366, filed ing range, while the second shaft has a smaller July 20, 1938, there are disclosed and claimed operating range that is coextensive with a porcertain remote control systems for radio receivers tion of the operating range of the first shaft. wherein the control of a radio receiver is effected The first shaft is operated in a step-by-step manby means of controlling impulses which actuate l5 ner by means of the controlling impulses and it a stepping mechanism to effect volume control, rotates free of the second shaft in response to station selection, and oil? and on actuation of the volume control impulses above mentioned; the energizing switch at the receiver, as well as but, when a train of station-selecting impulses other desirable functions with which the present is generated, the second shaft is operated in uniinvention is not directly concerned. In those son with the first S a to e f t S at on sel ctio control systems, the controlling impulses are sent at the same time that the receiver is muted or by means of a dial-controlled impulse generator silenced by the operation of the first shaft. It is which generates the controlling impulses under further provided that the first shaft returns to control of a finger-operated dial similar to a its home position following the last control imtelephone dial. For reasons which are not i pulse, while the second shaft is maintained in the portant here, two of the finger positions of the position to which it is actuated to thus maintain dial are reserved for volume control impulses, the desired tuning of the receiver, and when the and one of these finger positions is effective to first shaft is aga a ua d in esponse to a subcause generation of a pulse of fixed short durasequent train of station-selecting imp tion followed by a control impulse of controllable second shaft is returned to its home position andduration, while the other of these finger positions is again operated in unison with the first shaft. is effective to cause generation of two pulses of The homing of the first shaft is controlled by a fixed short duration followed by an impulse of homing relay or magnet.

controllable duration. One of the control imn he pe d g application of Francis pulse trains thus generated is adapted to effect Ri a ds Serial fi ed u y 20, 1938, a volume level change at the receiver in one dithere is disclosed and claimed a novel step-byrection, for example, an increase in the volume step positioning device wherein the homing aclevel; while the other impulse train is adapted tion is controll d y a v l m y mechto effect a volume level change in the opposite anism which eliminates the necessity of P direction, for example a decrease in the volume ing a homing relay and which renders the device level. The subsequent finger positions of the dial responsive to th frequency of Occurrence 0f S are reserved for the control of station-selecting Cessive Control impulses insofar a t e ho n means at the receiver, the particular station se-' action is concerned.

lected in any instance being determined by the By the present invention, there is p d a number of successive impulses of fixed short dun v l st pp mechanism h h s n ra y ration generated by the impulsegenerating similar to that of the said G i and pmeans under control of the dial. For example, son application and which is adapted to control if a train consisting of four successive short imthe positions of two rotatable elements and aspulses is generated, a certain station will be sociated switches in the manner above-menselected at the radio receiver, while if a train tioned but which embodies a simple and novel of five impulses is generated, another station -will be selected at the receiver, etc.

In the said copending Grimes and Thompson application, there is further disclosed a novel stepping mechanism comprising two shafts, one

adapted to control a step-by-step switch which effects volume control changes and also mutes or silences the receiver during station selection, while the other shaft is adapted to control station-selecting switches. The two shafts are rotatable relative to one another but are interconnected in a novel manner to efiect rotation of the second shaft when the first shaft is operating through a portion of its operating range. In

time-delay mechanism as an improvement over that of the said Richardson application. As in the Richardson device, the homing action of the present device is controlled by the time-delay means so that the homing action is effected a0- cording to the frequency of occurrence of the received impulses. It will be understood, therefore,

operating range of the first element, and the two elements being operated in unison over their coextensive ranges.

Another object of the invention is to provide a device of this character embodying novel means responsive to the frequency of control impulses for governing the homing action of the device.

Still another object of the invention is to provide a novel positioning device for controlling the position of a movable element in response to received control impulse trains, which device embodies novel means for controlling the homing action thereof according to the frequency of occurrence of the successive impulses.

A further object of the invention is to provide in a device of the stated character novel time delay means for effecting homing action after a predetermined interval following a control impulse, the said time delay means comprising a device wherein the delay action is obtained by the frictional engagement of a flexible cord with a stationary drum.

A still further object of the invention is to provide in a device of the stated character novel means for preventing th second element from getting out of step with the first element during tandemoperation of the two elements. Other objects and features of the invention will be apparent hereinafter.

In the drawings: Figure 1 is an elevational view of the complete device, showing both primary and secondary switch sections;

Fig. 2 an elevational view of the operating mechanism;

Fig. 3 is a fragmentary sectional view taken along line 3-3 of Fig. 2;

I Fig. 4 is a detailed sectional view taken along line 44 of Fig. 3;

Fig. 4a is a fragmentary perspective view of v the ratchet structure in inverted position;

Fig. 5 is a sectional view taken along line 55 of Fig. 2;

, further hereinafter.

is secured to one of the upright sides of support I, as clearly shown in Figs. 1 and 2. The relay 4, which constitutes the stepping relay, comprises a coil winding 6 and an armature l, the latter being pivotally secured at 8 to the supporting bracket 5 (see Fig. 5). A spring 9 serves to maintain the armature in its normal inoperative position and moves the armature to that position whenever the relay is deenergized. In operation, current impulses are supplied to winding 6 through leads shown in Fig. 1, and upon receiving a control impulse, the electromagnet of the relay attracts the armature 1 against the action of spring 9, as will be well understood, the armature pivoting about point 8 so that its lower end moves in a small arc. The armature carries an operating arm ID, the lower end of which serves as a stepping pawl. The arm l0 extends through a slot in the supporting base i (see Fig. '7) and moves in the slot whenever the armature l is actuated. An edge of the slot serves as a stop to limit the movement of the armature under the influence of spring 9.

As shown clearly in Fig. 3, the base I carries a stationary stud or pin it which supports the rotatable elements whose movements it is desired to control, as will be described presently.

The stud or pin II is supported by a stationary collar or sleeve l2, permanently secured to base i, carrying a set screw l3 which engages the stud, as illustrated. A primary ratchet wheel M is carried by sleeve l8 which is rotatably mounted on the stud H, and is urged to a normal or home position by means of a coil spring l5, one end of which is anchored to the primary ratchet at l6, while the other end of the spring is anchored to the sleeve 12 at H. Thus, the spring l5 resists rotary movement of ratchet l4, and returns the ratchet to its home position whenever the ratchet is released after actuation thereof. The stepping pawl operates ratchet l4, as described A switch arm I9 is carried by sleeve l8 and forms part of the primary switch section of the device.

The lower end of sleeve 18 is provided with diametrically opposed recesses 20 (see Fig. 4). which serve to seat the nose portions 2i on arms 22 of a cam member 23 partially encircling the lower end of the sleeve. A coil spring 24 surrounding sleeve It; has one end anchored to the ratchet I4 at 25, while the other end of spring 24 is anchored to the cam member 23 at 26. Thus, the

cam member 23 is resiliently carried by sleeve and particularly to Fig. 1, the device is assembled on a U-shaped base or support I which is adapted to be secured to mounting brackets 2 which in turn may be secured to a supporting panel 3.

The operating mechanism of the de-- vice is positioned within the U-shaped supp rt I,

and is constructed as follows. An electrome- I8 and rotates therewith. The cam portion 21 serves a purpose which will be explained presently.

A secondary ratchet 28 is carried by a collar or sleeve 29 which is rotatably mounted on the lower end of stud H, as shown clearly in Fig. 3. The ratchet 28 carries an extending arm 30 (see Fig. 1) which actuates a rotatable arm 3! on a shaft 32 rotatably mounted in the bearing structure 33 carried by the supporting panel 3. At its lower end the rotatable shaft 32 carries switch arms 34 and 35 which are arranged to engage successive arcuately spaced stationary contacts 36 and 31, respectively,.carriedv by an insulating support 38, which in turn is suspended from panel 3 by means of supports 39. The rotatable arms 34 and 35 whose positions are thus controlled by the secondary ratchet 28, together with the stationary contacts, constitute the second switch section of the device.

Referring now to Fig. 7, the switch arm I3 is arranged to engage successively a plurality of the armature I.

spaced stationary contact elements 40 in response to stepping movement of the primary ratchet I4 through the medium of the stepping relay. Actuation of the switch arm I9 beyond the contacts 40 causes the arm to engage the arcuate stationary contact M. In the specific application of the device to the control of a radio receiver, according to the method disclosed in the above-mentioned applications, the engagement of switch arm I8 with contacts 40 serves to control the volume of the radio receiver, while the engagement of the arm with the arcuate contact 4I serves to mute the radio receiver during station selection by the second switch section comprising contacts 34 to 31. ent invention is not concerned with the specific use to which the device may be applied, and its application to the control of a radio receiver is mentionedherein merely to illustrate one use of which the device is capable.

The arm 38 and its associated ratchet 28 are urged to the normal or home position, by a spring 42 (see Fig. '7) one end of which is secured to arm 30 at 43, while the other .end of the spring is secured to a lug 44 on the support I. In the home position of arm 30, the arm abuts against stop 30a carried by support I. A pawl 45 serves as a holding pawl for ratchet 28 so as to maintain the arm 38 in any position to which it is actuated. The pawl 45 is resiliently carried by a leaf spring 48 which is secured to a bracket 41 mounted on support I. On rotation of the ratchet I4, the pawl 45 is released by the cam member 23 simultaneously with engagement of arm I! with the arcuate contact 4I, thus, permitting the arm 30 and ratchet 28 to be homed by spring 42 preparatory to the station selection operation. Ratchet 28 carries a pin 48 (Fig. 1) which is engageable by a depending pin 49 on ratchet I4. The ratchet I4 serves to operate the ratchet 28 through the engagement of the two pins. This operation will be more fully described later.

As mentioned above, the lower end of arm I is formed so as to function as a stepping pawl which engages the primary ratchet I4. A spring 50 (see Figs. 2 and '7) has one end attached to the stepping pawl and has its other end anchored to support I at I, so that this spring helps to maintain the pawl against theguide slot so as to properly engage the ratchet I4 upon the operation of A holding pawl 52 (Figs. 7 and 8) for the ratchet I4 is pivotally secured at 53 to support I. A spring 54 has one end connected to the holding pawl at 55, while the other end of the spring is anchored to support I. This spring urges the pawl 52 into engagement with ratchet I4, as may be clearly seen in Fig. 8, but the pawl is normally held out of engagement with the ratchet by means to be described presently. When the holding pawl 52 is permitted to engage ratchet I4, however, it serves to maintain the ratchet in any position to which it is actuated by the steppingpawl I0. As control impulses are supplied to the stepping relay, the stepping pawl However, the pres- I0 operates the primary ratchet I4 in step-bystep fashion,-and the holding pawl 52 serves to maintain the ratchet I4 in the successive positions against the action of the homing spring I5.

One feature of the present invention resides in the provision of novel time delay means for controlling the operation of the holding pawl 52 so as to permit homing of ratchet I4 after a predetermined time interval following a control impulse. The details of the time delay device may be clearly understood by referring particularly to Figs. 8 and 9. Above the horizontal portion of support I, there is pivotally mounted a member 56 (see Fig. 9) whose pivot 51 is mounted on bracket 58 carried by support I. The member 58 comprises an arm 59 having a hooked end 88 engageable by arm ID. The member 58 also has formed thereon an integral extension 8| which passes normally through an opening in support I and engages the holding pawl 52, as shown in Figs. 7, 8, and 9. A relatively heavy spring 82 has one end secured to the pivoted member II at 63 and has its other end anchored to 9. lug 84 on support I. The spring 62 urges the pivoted member 56 in a directionto cause the pivoted member to move the holding pawl 52 out of engagement with ratchet I4, as shown in Fig. 8.

Since the spring 82 exerts a greater force on the holding pawl 52 than the force exerted thereon by the spring 54, the pawl is normally held out of engagement with ratchet I4 against the action of its associated spring 54. Whenever the stepping pawl I0 is actuated, however, the member 58 is moved thereby against the action of spring 62 in'such manner as to expand the same, thereby releasing the holding pawl 52 and permitting spring 54 to move the pawl into engagement with ratchet I4.

A stationary drum 65 is mounted upon support I and a flexible cord 66 is wound about the drum, there being sufiicient turns of the cord upon the drum to provide the required friction grip between said elements. One end of the flexible cord is secured to member 56 at 61, while the other end of the cord is attached at 88 to an end of a relatively weak spring 69, the opposite end of which is secured at ID to a bracket II carried by support I. Normally, the cord is taut on the drum, being so held by the springs 62 and 89. When the member 56 is moved by the stepping pawl against the action of spring 82, as above mentioned, a certain amount of slack of the cord is provided which is immediately taken up by spring 69. Further, the holding pawl 52 is permitted to engage ratchet I4, as above described. Following each control impulse, the stepping pawl I0 returns to its normal position, thus releasing the member 58; and as a result, the heavy spring 82 tends to return member 56 to its normal position, but the frictional engagement of the cord 66 with drum 65 imposes a frictional drag upon the return movement of member 56, thus providing a time delay in the return of the member 58. If a succeeding control pulse is applied in proper sequence, the member 58 is prevented from returning to its normal position and the holding pawl 52 is permitted to continue its engagement with ratchet I4. However, if a control impulse is not received within the timedelay period provided by the mechanism, the member 56 is returned to its normal position, causing the holding pawl 52 to be disengaged from ratchet I 4 and thus permitting homing of the ratchet. It will be seen, therefore, that after a properly timed series of impulses has been applied to the device, the homing action will take place after a predetermined -time interval following the last control impulse. It will be seen further, that the occurrence of the homing action is dependent upon the frequency of occurrence of the successive control impulses, so that the device operates properly only in response to properly timed control improvided by the mechanism just described will depend upon the design and adjustment of the elements constituting the said device. As shown in Fig. 6, the drum 85 may be eccentrically mounted upon a pin or stud l2 adjustably carried by means of a collar '58 and set screw i l.

By rotating the pin 82 to a desired position, the

be readily understood.

Considering now the operation of th complete device, let it be assumed that both of the ratchets M and 28 are in home position, as shown in Fig. 7. Upon the application of a series of control impulses to the stepping relay, the stepping pawl it is actuated to step ratchet l4, thereby moving the contact arm it over its associated stationary contacts. At the-same time, the stepping pawl it actuates the pivoted member 58 to permit the holding pawl 52 to engage the ratchet, as above described. During the application of properly timed successive control impulses, the holding position of the drum 85 may be adjusted to vary the action of thetime delay mechanism, as will.v

pins 48 and 68 engage one another, thus efiecting stepping action of ratchet 28 from its home position, as above described. When the control impulses cease, the ratchet M is homed but the second ratchet 28 is held by pawl #15. During homing of ratchet M the cam 23 isdefiected under pawl 85 by the curved end 271 (see Fig. 4a) so that the cam is unable to disengage pawl 35 from ratchet 263. i

It will be seen, therefore, that the first ratchet i8 is operable over a predetermined range, while the secondratchet 28 is operable over a range which is coincident with a portion of the operating range of the first ratchet. Further, the secondary ratchet is homed from anyposition to which it may have been actuated, preparatory ,to tandem movement of the two ratchets through pawl 52 is maintained in engagement with the it is actuated.- Following the cessation of the control impulses, the ratchet 28 is maintained in the last position to which it has been actuated, while the ratchet- I4 is homed after a predetermined interval, as above described. Thus, the second switch section is maintained in a selected position, determined by the number of impulses,

the medium of the cooperating pins 58 and t8.

As above described, the novel time delay mechanism which controls the homing action of the primary ratchet is-extremely simple in construction and operation, and yet operates eificiently to serve its intended purpose.

In addition to the principal switch sections of the device above described, there may be provided an auxiliary switch 75 (see Fig. '7), the

' spring arms of which tend to close the switch,

while the first switch section of the device is returned to normal or home position.

Itwill be understood, of course, that if the number of control impulses is not such as to move the contact arm l9 beyond the contacts 40, the

ratchet 28 and the switch section controlled thereby will not be operated. Such action might obtain, for example, when the contacts 40 are employed to control the volume ofv a radio receiver, as above mentioned, and where the device is actuated to vary the volume of the receiver but not to effect a station selection.

Assuming that the device has been operated, as above described, to move the second switch section to a selected position, when it is desired to select a different position, a diflerent series of impulses will be applied to the device. Remembering that the second ratchet 28 has been maintained in the position to which it was last actuated, the control impulses will'afiect operation of ratchet l4 and its switch arm l9 as above described. It will be remembered also that the cam member 23 is rotated by ratchet I4, and this cam mem is so arranged that it engages pawl just prio to the engagement of arm I9 with the arcuate contact 4|. As may be seen from Fig. 7, the cam portion 21 deflects the resiliently mounted pawl 45 sufiiciently to disengage the pawl from ratchet 28, thus permitting homing of the ratchet 28 and the second switch section under the influence of spring 42. Continued stepping rotation of ratchet 14 causes the pawl 45 to ride, 011 the cam portion 21, permitting the pawl to again engage ratchet 28. At the same time, the

but are held open during a predetermined portion of the operating cycle by a pivoted toggle member I6, one end of which acts as a cam, while the other-end is bifurcated toaccommodate pin 11 carried by ratchet 84, At a predetermined point in the operation of ratchet l4, this toggle mechanism operates to release switch 15, permitting itto close. This switch may be employed for any desired purpose with which the present invention is not concerned. The pin 11 may serve additionally to fix the home position of ratchet I4 by abuttingagainst a fixed stop Ha on support 1.

a Due to the rapidity with which such a devicev operates; it has been found that the second ratchet 28 tends to get out of step with the first ratchet. The momentum acquired by the second ratchet from the rapidly occurring successive impulses sometimes causes the second ratchet to advance more than a single step, thus causing the second switching section to move beyond the desired position. Obviously, when the device is used to control a radio receiver, such undesirable action may cause the selection of a station other than the one desired.

One form of device for eliminating this undesired action is disclosed and claimed in a copending application of Elmer 0. Thompson, Serial No. 277,270, filed June 3, 1939, now Patent No. 2,206,926, granted July 9, 1940. A further feature of the present invention resides in the provision of other novel means for maintaining the desired relation between the primary and secondary ratchets; As shown in Fig. 7, there is provided an auxiliary pawl I8 which is pivotally mounted at 19 on the support I, and is arranged for engagement with the second ratchet 28. A light spring is arranged to urge the pawl 18 toward the associated ratchet. On the pawl, however, there is provided an extending lug 8| (see Fig. 2) which engages the back of the stepping pawl l0. When the stepping pawl is in normal inoperative position, it holds the pawl 18 out of engagement with the ratchet 28. Upon each actuation of the stepping pawl I0, however, the pawl '8 follows the stepping pawl under the influence of spring 80, and the elements are so arranged that the nose of pawl 18 engages ratchet 28 immediately following the stepping action effected by the stepping pawl. Thus, each step-by-step movement by the ratchet 28 is accompanied by engagement of pawl 18 with the ratchet, thus preventing the latter from moving beyond a single step, Thus, there is provided a simple device in the form of the auxiliary pawl 18 whose action is. controlled by the stepping pawl in a'manner to prevent excess movement of the secondary ratchet. By the provision of this simple device, the above-mentioned undesirable tendency is eliminated.

From the illustration of the drawings and from the above detailed description, it will be seen that there is provided a step-by-steppositioning device which eliminates the necessity of providing a homing relay and in which homingis effected by a very simpleand readily adjustable time delay mechanism. Further,- the switch sections controlled by the device can operate through one step only at a time, thus eliminating any galloping tendency.

It will be understood, of course, that the present disclosure is not intended to limit the invention, which is capable of further embodiments or modifications, particularly in respect to the structural details. Such modifications are to be deemed within the scope of the invention.

I claim:

1. In a step-by-step positioning device, a movable element having a home position arranged for movement to successive operating positions, means for effecting step-by-step movement of said element to its successive positions in response to successive control impulses, means for urging said element to its home position, means for maintaining said element in each position to which it is moved, means responsive to cessation of an impulse for rendering said maintaining means ineffective, and frictional time-delay means comprising a drum and cable device for retarding the operation of said last-named means for a period suflicient to permit stepping of said element in response to a subsequent control impulse.

2. In a step-by-step positioning device, a movable element having a home position arranged for step-by-step movement to successive operating positions, means for urging said element to its home position, normally inoperative means for maintaining said element in each operating position, means responsive to successive control impulses for stepping said element and for ren- .dering said maintaining means effective, means for restoring said last-named means to normal position, and frictional time-delay means comprising a drum and cable device for retarding the action of said restoring means to thus delay homing of said element for a predetermined period following an impulse.

3. In a step-by-step positioning device, a retatable element having a home position and a plurality of successive operating positions. means urging said element to its home position, means including a ratchet and a spring-biased holding pawl for maintaining said element in its operating positions, means normally holding said pawl against the action of its spring out of engage 'ment with said ratchet, stepping means including a pawl arranged cooperatively with said ratchet for stepping said element to its operating positions, means responsive to successive control impulses for actuating said stepping means.

means operable by said stepping means for rendering the holding means for said holding pawl -stepping pawl for rendering said spring-biased inoperative, thereby causing said holding pawl to engage said ratchet, means for restoring said pawl-holding means to normal position, and frictional time-delay means comprising a drum and cable device for retarding the action of said restoring means to thus delay homing of said element for a predetermined period following an impulse.

4. In a step-by-step positioning device, a rotatable element having a home position and a plurality of successive operating positions, means urging said element to its home position, a ratchet connected to said element, a stepping pawl for stepping said ratchet, a holding pawl arranged to engage said ratchet to maintain said element in its operating positions, means urging said holding pawl into engagement with said ratchet, spring-biased means for maintaining said holding pawl normally out of engagement with said ratchet, means operable bythe actuation of said means ineffective. whereby said holding pawl is caused to engage said ratchet, a stationary drum, a cord connected to said spring-biased means and encircling said drum, and a spring arranged to i take up the slack of said cord, whereby the return of said spring-biased means to normal position is delayed for a predetermined interval by the frictional drag of said cord over said drum.

5. In a step-by-step positioning device, a rotatable ratchet wheel, a stepping pawl adapted to engage and step said ratchet wheel, a pivoted holding pawl arranged cooperatively with said ratchet Wheel, a spring arranged to urge said holding pawl into engagement with said ratchet. a pivoted member engaging said holding pawl and adapted to disengage the holding pawl from the ratchet wheel, a second spring connected to said member and adapted to move the same to its effective pawl-disengaging position, an actuator on said member engageable by said stepping pawl to move said member to ineffective position against the action of said second spring, thereby permitting said holding pawl to engage said ratchet wheel under the influence of said first spring, and means for delaying the return of said member to its effective position under the influence of said second spring following the stepping pawls release of said actuator.

6. In a step-by-step positioning device, a rotatable ratchet wheel, a stepping pawl adapted to engage and step said ratchet wheel, a pivoted holding pawl arranged cooperatively with said ratchet wheel, a spring arranged to urge said holding pawl into engagement with said ratchet, a pivoted member engaging said holding pawl and adapted to disengage the holding pawl from the ratchet wheel, a second spring connected to said member and adapted to move the same to its effective pawl-disengaging position, an actuator on said member engageable by said stepping pawl to move said member to ineifective position against the action of said second spring, thereby'permitting said holding pawl to engage said ratchet wheel under the influence of said first spring, a stationary drum, a flexible cord in opposed relation to said second spring and wound about said drum. and a third spring connected to said cord so as to take up the slack thereof, whereby to delay the return of said member to its effective position under the influence of said second spring following the stepping pawls release of said actuator.

'7. In combination, a pivotally mounted member. a first spring means continuously urging said r eeee ree from said predetermined position and then releasing the same, said first spring means being constructed and arranged to return said member to said predetermined position ate rate determined by the friction between said cord and'said drum. Y

GALD J. BARRY.

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