US2373056A

US2373056A - Precision balance

Info

Publication number: US2373056A
Application number: US478625A
Authority: US
Inventors: Seederer Jacob Emil
Original assignee: Individual
Current assignee: Individual
Priority date: 1943-03-10
Filing date: 1943-03-10
Publication date: 1945-04-03
Anticipated expiration: 1962-04-03

Description

April 1945- J. E. SEEDERER PRECISION BALANCE Filed March 10, 1945 4 Sheets-Sheet l I IG' .1.

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April 3, 1945. 1 E. SEEDERER 1 PRECISION BALANCE Filed March 10, 1943 4 Sheets-Sheet 3 57 INVENTOR.

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null/"Mum:mull f5 [NVE/V'TOE, ATTOMX 40 1 1 ll l ll Patented Apr. 3, 1945 UNITED STATES PATENT OFFICE PRECISION BALANCE Jacob Emil Seedercr, Englewood, N. J.

Application March 10, 1943, Serial No. 478,825

4 Claims.

This invention relate to precision balances of the chain type where a chaincomprising a great many small links is fastened with one end to the beam of the precision balance while the other end is fastened to mechanical means whereby it may be raised and lowered and thereby varying the active length of that part of the chain which is supported by the beam of the balance, and more specifically it relates to an improved mechanical arrangement whereby the movable end of said chain may be raised or lowered.

A great many so-called chain balance have been'suggested as exemplified by the following patentsf Becker, No. 1,295,259; Gattoni, No. 1,964,349; Becker, No. 1,986,995; Gattoni, No. 2,222,658; and others. Most of these patents are concerned with the details of the suspension of the chain as well as with the mechanical means for raising and lowering one end of same. Numerous methods have been suggested ranging from the lead screw type shown by Becker, U. S. No. 1,295,258 to the flexible shaft type of drive shown by Gattoni, U. S. No. 2,222,658. In all these patents the efiort has been mainly concerned with providing a smooth acting movement of the movable end of the chain without any back lash and providing a linear scale with vernier reading. The objects have been attained with varying success and with various advantages claimed for each type of arrangement. Most of these balances, however, have had one or more faults, most often in the mechanism for raising and lowering the one end of the chain. In some case the mechanism has been apt to be jammed or broken by incorrect or careless operators. In other cases, the operation may have been uneven and Jerky after a while or there may have been too much back lash. In the present invention I have provided a mechanism which is smooth and safe and dependable in operation which thereby overcomes the various faults found in other devices of this character.

The first object of my invention is, therefore, to provide a mechanism which will operate smoothly and which will not be subject to wear or changes of any kinddue to moisture or temperature, and which is dependable and emcient in operation.

Another object of my invention i to provide a safe means of stopping the operation of the chain raising mechanism at both ends of the travel,

' of this specification and in which like numerals designate like parts throughout the same.

Figure 1 is a front elevation of a precision bal- 4 ance embodying my invention,

Figure 2 is a section taken along line 2-2 in Figure 1,

Figure 3 is a. section taken along line 3-3 in Figure 1,

Figure 4 is an enlarged sectional elevation of the chain raising mechanism.

Figure 5 is a partial elevation of the stop mechanism in one end position,

Figure 6 is a partial elevation of the stop mechanism in the other end position,

:5 Figure 7 is a section taken along line 1-1 in Figure 5,

Figure 8 is a section taken along line 8-8 in Figure 4,

Figure 9 is a section taken along line 9-9 in Figure 4,

Figure 10 is a section taken along line Ill-l 0 in Figure 4,

Figure 11 is a section taken along line I |ll in Figure 4, and

Figure 12 is a sectional elevation taken along line I2l 2 in Figure 11.

In the drawings wherein for the purpose of illustration, is shown a preferred embodiment of my invention, the numeral 15 designates the outer case or cabinet enclosing the precision balance having column I 6, beam I! and scale pans la. The balance furthermore has the usual pointer l9 indicating balance upon dial and balancing screws 2| as well a the usual pan raising mechanism 22 operated by knob 23 on the front of the base 24. The base 24 is mounted upon a fixed support 25 which is placed centrally in the rear of the base and upon two adjustable supports 26 which may be adjustable by screws 21.

The weighing chain 28 is fastened at one end to the beam I! by means of the screw 29 and stud 30. The other end of the chain 28 is fastened to stud 3| by means of the adjustable hook 32 and screw 33, see Figure 11. The stud 3| is fastened to the slider 34 which is adapted to slide vertically in column 35 which is graduated into a scale on the front side, usually giving readings in milligrams. A Vernier scale 35 is fastened by means of screw 31 to the slider 34 and by means of this scale it is possible to read fractions of the division engraved upon the main scale on column 35, usually tenths of milligrams. The weighing chain thus hangs supported between the two

points

29 and 32 in the form of a true catenary. Each one of the two

points

29 and 32 support a part of the chain which is on their respective sides just as if the chain had been cut at the lowest point of the catenary curve. By sliding the slider 34 upward along column 35, therefore, the length of chain supported by the beam is shortened and the weight accordingly reduced.

The column 35 is mounted upon a base 38 and is U-shaped in cross-section as indicated in Fig ures 10 and 11. A cap 39 is placed upon its upper end and a short distance below said cap is placed a pulley 40 over which runs a second chain 4| which is fastened with one end to the slider 34 by means of the screw 42, see Figure 11. The other end of chain 4| is fastened to the bottom of groove "43 in pulley 44 which is mounted upon the shaft 45, see Figure 8. The pulley 44 has a cover 43 with an opening 41 through which the chain 4| may enter thereby providing a fool-proof protective housing for same. The cover 46 issupported upon a stationary bushing 470. which is supported in bracket 48 and which furnishes a bearing for shaft 45. The outer end of shaft 45 is provided with crank 49 which may be easily removed when not in operation. The bearing bushing 50 supports the outer end of shaft 45. By turning crank 49 it is thus possible to wind up chain 4| in groove 43 thereby raising the slider 34 along column 35 and thus shortening the length of the weighing chain 28 supported by the beam. When the crank is turned in the other direction, the weight of the slider 34 pulls the same down by gravity thereby unwinding th chain 4| from groove 43 and giving a. smooth and efiicient operation without back lash or slipping. The chain drive effected by means of pulley 40, chain 41 and pulley 44 is a considerable advantage over the various drives mentioned supra in that it is more positive in action and less subject to wear and getting out of order.

To prevent that the slider 34 may be driven too far up and the driving chain 4| thereby torn off Or stretched, I have provided a new and novel stop mechanism which is adjustable and which may b set for any suitable length of scale 35. This is accomplished by means of the two adjustable collars and 52 which are runningin a thread on shaft '45 and adjustable on same by means of set screws 53. The stop pins 54 and 55 are inserted in collars 5| and 52 respectively and are adapted to engage the stop 55, one end of which slides in groove 51' of bracket 48 and the other end of which is fastened in a nut 58 which is running in the threaded portion of shaft 45, see Figures 4, 5, 6 and 7. In Figure 5 is shown how the stop pin 54 strikes stop 53 when the slider 34 is in the extreme downward position, and Figured illustrates how stop pin 55 strikes stop 55 when the slider 34 is in the top position.

The shaft 45 is secured in place by collars 59 and 6B and spring 6| which provides a suitable amount of friction so as to give smooth and even operation. The bracket 48 is fastened to base 24 by means of screws 62, the holes for which may be slotted thereby providing longitudinal adjustment so that groove 43 can be properly lined up with the center of column 35. The base 33 supporting column 35 is mounted by means of nut 63 which is placed in a recess in the base 24. Chain 4| runs through the center of column 35 and through a slot in slider 34 to pulley 45 over which it is looped and the other end is fastened to slider 34 by means of screw 42 as described supra. This permits the chain 4| to run perfectly straight and without any friction other than that of pulley 40 thereby insuring a long life for the chain.

The operation of my invention has been described above in its essential details but it may be reiterated as follows:

The balancing of the oscillatory system is made by means of the usual adjustment until the indicator l9 reads zero on scale 25 with the slider in the top position and with the zero point of the vernier scale .35 in line with the zero point of the scale 35. If an article to be weighed is now placed upon the pan i8, the indicator I!) will move to one side. The slider 34 is now moved downward by turning crank 49 until the indicator |9 again reads zero on scale 25. The reading in milligrams is then made on scale 35 by means of the Vernier scale 36.

The operation of the stop mechanism, as mentioned supra, acts to prevent any damage to the driving chain 4| by limiting the number of rotations which can be made by crank 49. When crank 49, for instance, is turned in an anti-clockwise direction, thereby lowering slider 34, the nut 58 moves to the left on the threaded part of shaft 45 -as shown in Figure 1, until the stop pin 54 strikes the stop 55 as indicated in Figure 5. When the crank 49 is turned in the opposite direction, the nut 53 travels to the right until stop pin 55 hits stop 55 as shown in Figure 6.

It is to be understood that the form of my invention herewith shown and described, is to be taken as a preferred example of the same and that various changes in the shape, size and arran-gement of parts may be resorted to, without departing from the spirit of my invention or the scope of the subjoined claims.

Having thus described my invention I claim:

1. In a precision balance of the character described comprising a beam; a weighing chainv pulley in the shape of a narrow spool being fastened on the shaft of said drive mechanism; a driving chain fastened with one end to said second pulley and with the other end being looped over said free pulley and fastened with its other end to said slider, and a stop mechanism commounted in said cabinet, a beam mounted upon said column; a weighing chain fastened with one end to said beam; a graduated column, a slider moveable on said column, said slider supporting the other end of said weighing chain; a drive shaft rotatably mounted under said cabinet and having a removable crank on the side of same; a free pulley journalled at the top of said graduated column; a driving chain looped over said pulley and fastened with one end to said slider; a spool formed pulley fastened on the end of said drive shaft underneath said graduated column and having the other end of said driving chain fastened in the bottom of its groove, and a stop mechanism comprising a plurality of co-acting threaded collars adjustable on the shaft of said drive mechanisms; a threaded sleeve located on said shaft between said threaded collars and means preventing the rotation of said sleeve but permitting the longitudinal motion of same whereby the rotation of same may be limited in both directions.

3. In a precision balance of the character de scribed comprising a cabinet, a balance column mounted in said cabinet; a beam mounted upon said column; a weighing chain fastened with one end to said beam; a graduated column mounted perpendicularly at a distance away from said beam; a slider slidable vertically on said graduated column, said slider supporting the other end of said weighing chain; a drive shaft rotatably mounted under said cabinet and having a removable crank on the side of same; a free pulley journalled at the top of said graduated column; a driving chain looped over said pulley and fastened with one end to said slider; a spool formed pulley fastened 0n the end of said drive shaft underneath said graduated column and having the other end of said driving chain fastened in the bottom of its groove and a stop mechanism comprising a pair of collars adjustably mounted on said drive shaft, said collars having stop pins extending in opposite directions and engageably with a stop movable along a threaded portion of said drive shaft.

4. A stop mechanism for a precision balance chain drive comprising a drive shaft rotatably mounted, a removable crank engaged with one end to said drive shaft; a pair of adjustable collars fastened on said drive shaft, said collars having stop pins extending toward one another in opposite relation; a nut running in a thread on said drive shaft between said adjustable collars and a stop pin fastened in said nut and engageable with outside guide means for the prevention of the rotation of said nut, whereby said nut will travel along said thread on the drive shaft until one of said step pins in the adjustable collars will strike the stop pin of the nut.

' JACOB E. SEEDERER.