US2110196A - Tuning system fob radio receivers - Google Patents

Description

March 8, 1938. H, E. BRQHMAN TUNING SYSTEM FOR RADIO RECEIVERS Filed Sept. 6, 1935 3 Sheets-Sheet l 3 Sheets-Sheet 2 H. E. BROHMAN Filed sept. e, 1935 March 8,'1938. H. E. BROHMAN TUNING SYSTEM` FOR RADIO RECEIVERS s sheets-#sheet s Filed Sept. 6, 1955 l Il.

Patented Mar. 8, 1 938 4UNITED STATES yPATENT OFFICE TUNING SYSTEM FOBBADIO RECEIVERS Howard E. Brohman, Marlon, Ind.. assigner to Case Electric Corporation, Marion, Ind.

Application september s. 1935. serial No. 39,391

7' Claims. 'I'he present invention relates generally to tuning systems for radio receivers. More particularly the invention relates to that type of tuning system which is designed for use with a cabinet-housed radio receiver having a variable condenser and a range switch, and comprises: (1) a knobequipped shaft and driving mechanism between the shaft and the rotor `of the condenser for use in manually turning and adjusting the rotor in connection with tuning of. the radio receiver and, (2) a dial and pointer for indicating the setting of the condenser. t

One object of the invention is to provide a tuning system of this type which is an improvement upon previously designed systems of the same general character by reason of the fact that it includes a high speed drive between the knobequipped shaft and vthe driving Vmechanism whereby. the mechanism may be driven by the 20 shaft in aspeedy or quick manner for quick adjustment or setting of the rotor of the condenser, and also includes a low speed drive between the shaft and the mechanism whereby a minute setting or adjustment of the condenser may be obtained.

Another object of the invention is to provide a tuning system of the last mentioned character in'which the knob-equipped shaft is mounted for longitudinal slidable movement as well as rotation, and the` high speed drive between the shaft and the driving mechanism is brought into play when the shaft is shifted in one direction and the low speed drive is brought into play when the shaft is shifted in the opposite direction.

Another object of the invention is to provide a radio tuning system of the type and character under consideration in which the driving mechanism between the knob-equipped shaft and the rotor of the condenser comprises a pulley system in the form of a drive pulley and a driven pulley and-also comprises speed reducing gearing between the driven pulley and the shaft which supports rotatably and forms a part of the condenser rotor.

Another object of the invention is to, provide a tuning system in which the dial has 'substantially circular, concentrically' arranged wave bands which are calibrated in kilocycles, and the pointer is connected to the driving mechanism between the knob-equipped shaft and the rotor of the condenser so that it swings throughout an arcv of approximately 340 when the condenser rotor is shifted from a position'wherein the plates thereof are in completely overlapped relation with respect to the plates of the condenser stator into a position wherein the plates are out of registry or lapped relation with respect to the stator plates.

A further object of the invention is to provide a tuning system of the type and character under 5 consideration which includes in addition to the regular tuning pointer a Vernier pointer which is adapted to rotate completely around the dial and indicates fractional positions of the main pointer with respect to kilocycle calibrations on the wave bands or scales.

An additional object ofthe invention is to provide a tuning system which is generally of new and improved construction and includes a novel dial arrangement and means for illuminating the dial.

Other objects of the invention and the various advantages and characteristics of the present tuning system will be apparent to those skilled in -the art from a consideration of vthe following detailed description.

The invention consists in the several novel features which are hereinafter set forth and are more particularly dened by claims at the conclusion hereof. 25

In the drawings which accompany and form a part of the present specification or disclosure and in which like letters and numerals of reference denote corresponding parts throughout the several views: 30

Figure 1 is a front view of a radio receiver having a tuning system embodying the invention;

Figure 2 is a plan view showing the arrangement of the gear train and other details of construction;

Figure 3 is a vertical section showing in detail the construction and arrangement of the various parts which comprise the system;

Figure 4 is a sectional view of certain of the gears of. the gear train between the driven pulley and the rotor of the condenser; and

Figure 5 is a section on the line 5 5 of Figure 3.

'I'he tuning system which forms the subject matter of the invention is designed for use in 45 connection with a radio receiver R of conventional or standard type. As shown in Figure 1 of the drawings, this receiver comprises a cabinet C for housing the various operating parts thereof. The cabinet is adapted to be placed upon a table or any other support as well understood in the art, and includes a front Wall c, a base c1, sides c2 and a top c3. .The front wall is suitably secured to the front margin of the base c1, and the upper portion thereof. is semicircular and has for tuning purposes.

Aso

a large circular aperture c. The sides #cil are secured to the side edges or margins of the front wall c, and together with the front wall., base and t 4p of the cabinet form a compartment or cham r for the operating parts of the radio receiver. The top c:l is curved in conformity with the top portion of the front wall and the ends thereof join and form'continuations of the upper ends ofthe sides c. v

The operating parts of the radio receiver include a variable condenser 6. 'I'he latter operates as the tuning medium for the receiver and consists of a stator 1 and a rotor 8. 'As shown in Figure 3 of the drawings the stator is mounted on a bracket 8 and consists of a series of equidistantly spaced. metallic plates I8. These plates are flxedly secured to a pair of conductors II which are arranged in parallel relation and together with a. plurality of vertically extending plates I4 form a frame for the condenser. The rotor 8 is supported by the frame and consists of a shaft I3 and a plurality of equidistantly spaced, metallic plates I2. The shaft `I3 is journalled in the plates I8 of the condenser frame and is adapted to be rotated as hereinafter described The plates I2 are fixedly secured to the central portion of the shaft are adapted in response to rotation of the shaft I3 to be swung into and out of interleaved relation with the plates I8 of the stator. By swingingthe plates I2 into and out of interleaved or lapped relation with respect to plates of the stator, the capacity of the radio receiver may be changed and different radio broadcasting stations obtained as well as understood in the art. The bracket 8.15 suitably supported above the base c1 of the cabinet C and supports the condenser 8 so that the shaft I3 of the stator extends at right angles to the front wall c and is positioned behind the aperture c4.

f The tuning system includes as a part thereof novel and improved mechanism for rotating or tuning the rotor of the condenser. This mechanism comprises a horizontally extending shaft I6, a pulley or drive element I6, a belt I1. a pulley I8 and a gear train between the pulley I8 and theA shaft I3 of the condenser rotor. The shaft I6 is disposed directly beneath the aperture c* and extends through a hole cis in the front wall c of the cabinet C. It is provided at its outer or front end with a knob I9 and is carried by a U-shaped bracket 28 so that it is `rotatable and also slidable longitudinally. The bracket 28 comprises a pair of upstanding legs 2I and 22 and a horizontally extending connecting part 23. The leg 22 f'lts against and is connected to a depending leg 8 on the front end of the bracket 8. The legs of the bracket 28 have aligned holes through which the shaft i6 extends. The knob I8 has a socket for receiving the extreme outer end of the shaft I6 and has a setscrew 26 whereby it is flxedly secured to the shaft. The pulley I8 is loosely mounted on the shaft I6 and is disposed between the upstanding legs 2| and 22 of the bracket 28. The belt I1 extends around. and forms a driving connection between, the pulleys I8 and I8. As shown in Figure 3, the pulley I8 is flxedly secured to a sleeve 26 which is loosely mounted on a shaft 26. The latter is supported at its inner end by a plate 21 which extends parallel to and is disposed behind the front wall c of the cabinet C and is connected at its lower end by an angle bracket 28 to the front end of the bracket 8. -The gear train between the pulley I8 and the shaft I3 of I3 and the rotor 8 of the condenser consists of a pinion 29 which is formed as an integral part of the inner end of the sleeve 26 and is disposed directly behind the pulley I8; a gear 30 which meshes with and is driven by the pinion 28 and is located beneath and'at one side of the sleeve 26; a pinion 3| which is fixed to rotate with and forms the hub of the gear 30 and is mounted on a pin or stud 32 on the plate 21; and a gear 33 which meshes with and is driven by the pinion 3l and is iixedly secured to the front end of the rotor shaft I3. When the pulley I6 is rotated in one direction the belt I1, the pulley I8 and the gear train between the last mentioned pulley and the rotor shaft I3 operate to swing the rotor in one direction with respect to the stator. Reverse rotation of the pulley I8 operates to effect reverse rotation or swinging of the rotor. A flanged roller 34 serves to keep the belt I1 taut in order to maintain at all times a driving connection between the pulleys I6 andl I8. This roller is mounted on a pin 36 which is secured to and projects rearwardly from the distal end of an arm 36 which is pivotally mounted on and extends upwardly from a bolt 31 on the leg 2l of the U-shaped bracket 20. The arm 36 `extends angularly with respect to the vertical and as a result its weight together with that of the roller operates to urge the roller outwardly with respect to one of the reaches of the belt and thus to tighten the belt. An advantage of employing the gear train between the pulley I8 and the shaft I3of the rotor is that the tension of the belt resulting from the operation of the roller or belt tightener 34 is not transmitted to the shaft I3 of the rotor and. the rotor isv thus not likely to be thrown out of alignment with respect to the stator of the condenser.

The shaft I6 is adapted to drive the pulley I6 through a direct or high speed drive and also through an indirect or low speed drive.

The high speed drive comprises a cup-shaped clutch member 38 which'has a hub 38 and is disposed between the pulley I8 and the leg 2I of the U-shaped bracket 2I'I. The hubas shown in Figure 3 of the drawings is mounted on the shaft I6 and is fixed tothe latter by means of a setscrew 48. so that it together` with the clutch member, isjsecured to rotate with the shaft in response to turning of the knob I8.. 'I'he clutch member 38 is adapted when the shaft I6 is shifted rearwards to slide over and engage a circular clutch member 6I on the front end of the pulleyV I6. When the cup-shaped clutch member engages the member 4I the pulley I8 is securedA to' the shaft I6 so that it is rotatable therewith. Thus when the shaft I6 is shifted rearwards so as to bring the cup-shaped member 38 into engagement or gripping relation with the circular clutch member 4I, a direct drive is established between the shaft I6 and the pulley I8 whereby the pulley may be rotated in either direction by manipulation of the knob I8. When the shaft I6 is shifted outwards by pulling on the knob I9. the cup-shaped clutch member 38 is brought out of engagement or gripping relation with the clutch member 4I and the direct or high speed driving mechanism between the shaft I5 and the pulley I8 is broken.

The indirect or low speed drive between the shaft I6 and the pulley I6 consists of an annular series of balls 62 `around the shaft I6 and a ringshaped element 63 around the balls. The balls l2 are confined between, and engage the inner faces oi', the rear end of the pulley I8 and a ner end of the pulley lvolve or rotate therewith. Since the balls travel rotates, the pulley disk 44' on the rear end of the shaft I 5. The

vring-shaped element 43 is .formed oi three pieces.

of sheet metal. The inner or intermediate piece serves as a spacer for the outer pieces and is secured to the horizontally disposed connecting part 23 of the U-shaped bracket 20 in such manner thatthe element 43 is lxedly or rigidly secured in place. The fronhsheet metal piece of the ring-shaped element is xed to the intermediate piece and embodies at the inner margin thereof a forwardly extending flange 45. The rear sheet metal piece of the ring-shaped element 43 is the sam in size and shape as the front piece and has a rearwardly extending ange 46. 'Ihe flanges 45 and 46 form a V-shaped groove 41 therebetween in which the balls 42 are adapted to travel. The shaft I5 is provided with an annular groove 48 at its rear end. This groove vis located or positioned on the shaft so that it re`- ceives the balls 42 when the shaft is shifted rearwardly so as to engage the cup-shaped clutch member 38 and connect the pulley for direct or high speed drive from the shaft. When the balls 42 are in the groove 48 they are loose with respect to the flanges 45 and 46. When the shaft I5 is shifted outwards so as to disconnect the direct or high speed drive between the shaft and the pulley I 6, the balls 42 are 'moved outwards;

into engagement with the flanges 45 and 46. As a result of this when the shaft I5 is rotated, the balls are caused to travel slowly around the anges and because of their contact with the in- I6 cause the pulley'to rearound the flanges more slowly than the shaft I6 turns at a reduced or slower speed with respect to the shaft. When the shaft is shifted rearwards so as to connect the pulley for direct or high speed drive by the shaft, the balls seat in the groove 48 and since they are not urged outwardly into contact withthe flanges they do not revolve or travel around the ring-shaped element 43 in response to rotation of the shaft. 'Ihe pulley I6 is held against axial displacement relatively to the bracket 2'8 by means of an L-shaped bracket 49. 'I'his bracket is secured to the connecting part 23 of the bracket 20 and is arranged so that one leg thereof projects into an annular groove 50 in the rear end of the pulley I6.

In addition to the mechanism.- for turning or rotating the stator of the condenser, the tuning system comprises a dial 5| and a main pointer 52. These two elements or parts of the tuning system serve as an instrumentality for showing the setting of the condenser and permitting the user of the radio receiver R to locate different broadcasting stations. 'I'he dial 5| is located I directly behind the aperture c4 in the upper por- 1 edges of the glass plate tion of the front wall c of the cabinet C, and comprises a square glass plate 53. 'Ihis plate is mounted in a sheet metal frame 54 and has a high wave length band 55, an intermediate wave length band 56 and a low wave length band 51. A

The frame 54 is square and has a forwardly extending marginal ilange 58 which surrounds the 53 and serves to hold the glass plate in place. The upper portion of the frame is deflected or stamped rearwardly to formv a boss 59 which is secured by a stud 60 to an ear of the plate 21. The lower The low wave length band glass plate .53 and U-shaped bracket 20. By connecting the boss 58 to the plate 21 and the boss 62 to the U- shaped bracket, the frame together with the glass plate 53 is secured tlxedly ln place and is held at a small distance behind the portionof the front wall c which denes the aperture c4. The dial 5| is covered or protected by a glass disk 64. This disk is mounted in a sheet metal ring 65 which lits within the aperture c* and has an outwardly extending circular flange 66 at thei'ront margin thereof. 'I'his ange, as shown in I ilgure 3 of the drawings, covers the aperture c4 and engages the front face of the front wall c of the cabinet. The ring 65 is held in place by means of a springwire member 61 which surrounds the rear portion of the ring and extends between the rear face of the front wall c of the cabinet andan outwardly extending flange 58 on the rear end of the ring. The high wave length band 55 consists of a 340 arc 55a and kilocycle calibrations 55b extending radially inwards fromf the arc. The intermediate wave length band 56 consists of a 340 arc 56a and an annular series of kilocycle calibrations 56b which extend radially inwards from the arc 56a. 'I'his arc 55a is smaller than'and is concentri'cally arranged with respect to the arc 55u of the high wave length band 55. 51 consis'ts of a 340 arc` 51 and an annular series of kilocycle calibrations or graduations which extend radially inwards from the arc 51e. 'I'he latter arcl as shown in Figure 1 of the drawings, is smaller than the arc 55n trically arranged main pointer 52 is relatively to the latter. The disposed infront of the glass plate 53 and is fixed to and radiates from the outer or front end of the shaft 26. The shaft extends through the center of the glass plate and is driven from the pinion 3| by means of a gear 69. This gear meshes with said pinion 3| and is xed to the inner or rear end of the shaft 26. When the rotor 8 of the condenser is turned or rotated by manipulation of the knob I9, the shaft 26 rotates and in turn swings the pointer 52 over the bands 55. 56 and 51. The gear 69 is of such size that the pointer travels throughout an arc 'of 340 when the condenser rotor is rotated from a position wherein the plates I4 thereof are in complete overlapped relation with respect to the plates of the condenser stator into a position wherein the rotor plates are out of overlapped relation with respect to the stator plates. By having the pointer rotate throughout an arcv of 340 the kilocycle calibrations of the wave length bands may be spaced sufnciently far apart so that an accurate setting of the radio receiver may be readily obtained. If desired, numbers may be associated with the kilocycle calibrations in order to indicate or show the numerical value or amount of the kilocycles.

In order to show fractional positions of the pointer v52 with respect to the kilocycle calibrations of the wave length bands a Vernier pointer 10 is provided. This pointer is fixed to and radiates from the outer or front end of the sleeve 25,. The latter projects through the center of the serves during setting Aof the condenser to rotate the pointer 10. The latter is adapted to swing 360 and due to the character and type of gearing which is employed to drive the shaft 26 and the pointer 52 swings once around the dial 5I during a 30" travel of the pointer 52. By employing the vemier pointer 10 it is possible accurately to set the radio receiver to receive programs from any broadcasting staof the band 56 and is concention. In order to facilitate adjustment or setting of the radio receiver a scale 1i is associated with the vernier pointer 10. 'This' scale encircles the high wave length band 5B and consists of graduations 1I which as shown in Figure 1 of the drawings are sixty in number and are arranged in an annular series. Numerals such, for example, as the hour markings of a clock are associated with several of the numerals- 1ib to facilitate proper positioning of the vernier pointer in connection with locating any given or known radio broadcasting station.

In order to illuminate the dial 6I an electric light 12 is mounted at each side of .the frame 54. The lights 12 are disposed in sheet metal housing 13 on the frame sides, and light therefrom is permitted to pass into the space between the glass disk 64 and the'dial 5i by way of slots 14 in the side parts of the marginal flange 58 of the frame 5I. In order to produce an iridescent effect the numerals and graduations of the scale 1I and the arcs and kllocycle calibrations of the wave length bands 55, `56 and 61 are painted into grooves in the back face of the glass plate 53. This plate 53 is preferably backed with a paper facing 15 which is cemented .or otherwise secured to the outer or front face of the frame, Thevlights 12 are suitably supplied with current and are controlled by a switch (not shown) which is operated by a knob IB on the front wall vc of the cabinet C.

The radio receiver R has a range switch 11 (see Figure 2) whereby it may be set for high.. intermediate or low wave length reception. This switch is mounted on the bracket 9 and the improved tuning mechanism includes a device for controlling or operating the switch. This device comprises a sleeve 18 which is mounted on and is rotatable relatively to the central portion of the shaft I5. As shown in Figure 3 of the drawings the sleeve extends through the hole ca in the front-wall c ofthe cabinet C, and is provided with a knob 19 whereby it may be turned. The knob is located behind the knob I9 and is tlxedly secured to the front end of the sleeve by means of set-screw 8U. The rear end of the sleeve is provided with a drum 8i and is connected to operate the range switch 1 1 by means of a belt 82 and a drum 83. The latter is mounted on a switch operating shaft 84 at one e side of the bracket 20. The belt 82 extends around the drums 8| and B3 and serves in response to rotation ofthe sleeve 18 to rotatethe shaft 84 and control the range switch 11. By mounting the sleeve 18 on the shaft Il the device for actuating or controlling the range switch 11 is conveniently located with respect to the knob Il and it is possible for the user of the radio receiver to operate the switch or adjust the condenser without moving his or her hand from one point on the cabinet C to another. The sleeve 1I is held against axial displacement by means of a bracket IB whichis fixed to the upstanding leg 2l of the bracket 20 and engages the front end of the drum Bi.

The herein described tuning system is essentially a simple one and may be manufactured at a low and reasonable cost owing to the small number of parts and the simplicity of its construction.

The invention is not to be understood as restricted to the details set forth, since these may be modified within the scope of the appended claims, without departing from the spirit and scope of the invention.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In combination with a radio receiver having a variable condenser in the form of a stator and a rotor mounted to rotate into and out of lapped relation with the stator, a tuning system for. the receiver comprising a gear train connected to rotate the rotor for tuning purposes. a knobequipped condenser actuating shaft mounted to rotate and slide longitudinally, a. driving connection between the shaft and the' gear train including a pulley mounted loosely on the shaft, clutch means rlxed to the. shaft and adapted upon shift of the shaft in one direction to engage one end of the pulley to form a direct driving connection between the pulley and the shaft, and means adapted upon shift of the shaft in the opposite direction to form a low speed driving connection between the shaft and the pulley, said last mentioned means including an annular series of balls encircling the shaft and engaging the other endof the pulley.

2. In combination with a radio receiver having a variable condenser in the form of a plate-type stator and a plate-type rotor mounted to rotate into and out of lapped relation with the stator, a tuning system for the receiver comprising a rotatable mounted shaft having a finger knob at one end thereof for turning purposes, a sleeve shaft, a driving connection between the two shafts whereby turning of the knob equipped shaft will result in turning of said sleeve shaft, a tuning dial having a hole therein through which one end of said sleeve shaft extends, a Vernier pointer adapted to coact with the dial fixed to and radiating from said one end of said sleeve shaft and a gear train between the rotor of the condenser and the other end of said sleeve dshaft whereby said rotor is rotated with respect to the stator in response to turning of said sleeve shaft by the knob-equipped shaft, a third shaft centrically positioned with respect to said sleeve shaft having an end extending through said hole in the tuning dial, a main pointer xed to and radiating from said end of the third shaft, and driving means between one of the gears of the gear train and the third shaft for rotating the third shaft at a lower rate of speed than the said sleeve shaft during turning of the latter by said knoblequipped shaft.

, 3. In combination with a radio receiver having a variable condenser in the form of a plate-type stator and a plate-type rotor mounted to rotate into and out of lapped relation with the stator, a tuning system for the receiver comprising a rotatable mounted shaft having a finger knob at one end thereof for turning purposes, a sleeve shaft, a driving connection between the two shafts whereby turning of the knob equipped vshaft will result in turning of said sleeve shaft, a

tuning dial having a hole therein through which one end of said sleeve shaft extends and also having a substantially circular scale around the hol a vernier pointer adapted to coact with and swing over the scale of the dial ilxed to and radiating from said one end of said sleeve shaft, a third shaft centrically positioned with respect to said sleeve shaft having an end extending through said hole in the tuning dial, a main pointer ilxed to and radiating from said end of the third shaft, a gear train between the rotor of the condenser and the other end of said sleeve shaft whereby said rotor is rotated with respect to the stator in response to turning of said sleeve between one of the gears of said gear train and the third shaft whereby said third shaft together with the main pointer thereon is rotated substantially 340 in one direction when the rotor is swung from its lapped relation into lunlapped position with respect to the stator and when said third shaft together with the main pointer is rotated substantially 340 in the other direction the rotor of the condenser is swung or rotated from said unlapped position into lapped relation with respect to the condenser stator and the rate of rotation of said third shaft is lower than' that of the second shaft. 1

4. In a radio device the combination of a variable condenser actuating and indicating mechanism comprising a variable condenser having a rotatable shaft, a dial with which a main pointer and a 'Vernier pointer are associated, a sleeve shaft to which the vernier pointer is secured. means associated with said sleeve shaft for manual operation thereof, a gear wheel separately mounted and driven from said sleeve shaft, a shaft located within said sleeve shaft to which the main pointer is secured and driving means driven by said gear wheel for turning said shaft to which the main pointer is secured and for turning the rotatable shaft of said variable condenser.

5. In combination witha radio receiver having' a variable condenser in the form of a multiplate stator and a multi-plate rotor mounted to rotate into and out of lapped relation with the stator, mechanism for visibly ascertaining the tuning adjustment of said condenser comprising a tuning dial, a main pointer and a vernier pointer coacting with the scale of said tuning dial, mechanism for tuning the receiver comprising a knobequipped shaft. a-main pointer shaft, a vernier pointer shaft concentrically positioned with respect to said main pointer shaft, a belt and pulley connection between the knob-equipped shaft and the said vernier pointer shaft, a gear train between the said Vernier shaft and said main pointer shaft comprising an intermediate gear wheel,

4 and driving means between said gear train and the rotor of the condenser whereby said rotor is swung with respect to the stator in response to the turning of the knob-equipped shaft and the relative movement and positioning of the rotor is indicated by said pointers on the tuning dial.

for rotating said fine adjustment pointer shaft,

and gear means driven by said ne adjustment pointer shaft comprising a separately mounted gear wheel driverfor driving said coarse adjustment pointer shaft and said first mentioned gear wheel. y

7. In combination with a radiofreceiver having a variable condenser in the form of a plate-type stator and a plate-type rotor mounted to rotate into and out of lapped relation with thestator, a tuning system for the receiver comprising' a rotatable mounted shaft having a'nger lmob atv one end thereof for turning purposes, a sleeve shaft, a driving connection between the two shafts whereby turning of the knob-equipped shaft will result in turning of said sleeve shaft, a tuning dial having a hole therein through which one end of said sleeve shaft extends, a vernier pointer fixed to and radiating from said one end of said sleeve shaft and adapted to coact withV the scale of said tuning dial, a third shaft mounted within said sleeve, shaft having one end extending through said hole in the tuning dial, a main pointer xed to and radiating from the said end of the third shaft, a gear wheel driver separately mounted and driven by said sleeve shaft, and gear means for driving said rotor by said -gear wheel driver whereby said rotor is rotated with respect to the stator in response to turning of said sleeve shaft by said knob-equipped shaft and means for rotating the third shaft by said gear wheel driver at a lower rate of speed than the said sleeve shaft during turning of the latter by said knob-equipped shaft.

HOWARD E. BROHMAN.

Images