39 «»

NBS TECHNICAL NOTE

437

DISCLOSURES ON:

Autosort - An Automatic Collating and Sorting Machine,

Optical Heterodyne Refractometer,

Liquid Metering Pump,

Stable Wideband Relaxation Oscillator Using Three

Inverting Amplifiers, and

Seat Belt Webbing Abrasion Resistance Testing Machine

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U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

SWmMMmi
THE NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards1 provides measurement and technical information services

essential to the efficiency and effectiveness of the work of the Nation's scientists and engineers. The

Bureau serves also as a focal point in the Federal Government for assuring maximum application of

the physical and engineering sciences to the advancement of technology in industry and commerce. To

accomplish this mission, the Bureau is organized into three institutes covering broad program areas of research and services: THE INSTITUTE FOR BASIC STANDARDS . . . provides the central basis within the United

States for a complete and consistent system of physical measurements, coordinates that system with the measurement systems of other nations, and furnishes essential services leading to accurate and uniform

physical measurements throughout the Nation's scientific community, industry, and commerce. This

Institute comprises a series of divisions, each serving a classical subject matter area: —Applied Mathematics—Electricity—Metrology—Mechanics—Heat—Atomic Physics—Physical

Chemistry—Radiation Physics—Laboratory Astrophysics2—Radio Standards Laboratory,2 which

includes Radio Standards Physics and Radio Standards Engineering—Office of Standard Refer- ence Data. THE INSTITUTE FOR MATERIALS RESEARCH . . . conducts materials research and provides

associated materials services including mainly reference materials and data on the properties of materials. Beyond its direct interest to the Nation's scientists and engineers, this Institute yields services which are essential to the advancement of technology in industry and commerce. This Institute is or- ganized primarily by technical fields: —Analytical Chemistry—Metallurgy—Reactor Radiations—Polymers—Inorganic Materials—Cryogenics2—Office of Standard Reference Materials.

THE INSTITUTE FOR APPLIED TECHNOLOGY . . . provides technical services to promote the use of available technology and to facilitate technological innovation in industry and government. The

principal elements of this Institute are

:

—Building Research—Electronic Instrumentation—Technical Analysis—Center for Computer Sci- ences and Technology—Textile and Apparel Technology Center—Office of Weights and Measures —Office of Engineering Standards Services—Office of Invention and Innovation—Office of Vehicle

Systems Research—Clearinghouse for Federal Scientific and Technical Information3—Materials

Evaluation Laboratory—NBS/GSA Testing Laboratory.

1 Headquarters and Laboratories at Gaithersburg, Maryland, unless otherwise noted; mailing address Washington, D. C,

20234.

2 Located at Boulder, Colorado, 80302.

3 Located at 5285 Port Royal Road, Springfield, Virginia 22151.
UNITED STATES DEPARTMENT OF COMMERCE

Alexander B. Trowbridge, Secretary

NATIONAL BUREAU OF STANDARDS • A. V. Astin, Director

NBS TECHNICAL NOTE 437

ISSUED NOVEMBER 1967

DISCLOSURES ON:

Autosort - An Automatic Collating and Sorting Machine,

Optical Heterodyne Refractometer,

Liquid Metering Pump,

Stable Wideband Relaxation Oscillator Using Three

Inverting Amplifiers, and

Seat Belt Webbing Abrasion Resistance Testing Machine

Editors: David Robbins and Alvin J. Englert

NBS Technical Notes are designed to supplement the Bureau's regular publications program. They provide a means for making available scientific data that are of transient or limited interest. Technical Notes may be

listed or referred to in the open literature.

For sale by the Superintendent of Documents, Government Printing Office Washington, D.C., 20402 - Price 25 cents
NBS Technical Notes, with "Disclosures On" in their title,

contain devices, methods and systems developed by the primaryoperating units of the Commerce Department and under contract

with the operating units or departmental staff offices.

Other disclosures on various subjects may be found in NBS

Technical Notes 237, 253, 263, 282, 287, and 295.

All property rights in the devices, methods, and systems

described in the above disclosures, unless otherwise noted,

have been retained by the United States Government as represented by the Secretary of Commerce.

ii
TABLE OF CONTENTS

Title Author (s)

Autosort - An Automatic

Collating and Sorting

Machine

Optical Heterodyne

Refractometer

Liquid Metering Pump

Ballard Jamie son

Donald O. Lambert

Central Intelligence Agency

Washington, D. C.

Lynn L. Huffman

Bureau of Census

Washington, D. C.

Lockett E. Wood

Moody C. Thompson, Jr. Environmental Science

Services Administration

Boulder, Colorado

Walter D. Komhyr

Environmental Science

Services Administration

Boulder, Colorado

Stable Wideband Relaxation

Oscillator Using Three

Inverting Amplifiers

Seat Belt Webbing Abrasion

Resistance Testing Machine

Rufus E. Gordon

Environmental Science

Services Administration

Silver Spring, Maryland

Alfred B. Castle, Sr.

National Bureau of Standards

Washington, D. C.

iii
ABSTRACT

This booklet presents descriptions and drawings of

five devices that embody interesting and unusual solutions

to problems frequently encountered in their respective fields,

The devices are:

Autosort - An Automatic Collating and Sorting

Machine

Optical Heterodyne Refractometer

Liquid Metering Pump

Stable Wideband Relaxation Oscillator Using

Three Inverting Amplifiers

Seat Belt Webbing Abrasion Resistance Testing

Machine.

Key Words:

automatic document distribution, programmed document

distribution, rotatable document bin array, optical refractive

index, laser beam phase shift, laser heterodyning, flexible

tubing pump, liquid metering pump, relaxation oscillator,

inverting amplifiers, seat belt webbing abrasion, abrasion

resistance testing.

iv
AUTOSORT - AN AUTOMATIC COLLATING AND SORTING MACHINE

Ballard Jamieson

Donald O. Lambert

Lynn L. Huffman

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Donald O. Lambert

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Ballard Jamieson

Donald O. Lambert

Lynn L. Huffman

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Donald O. Lambert

Lynn L. Huffman

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AUTOSORT - AN AUTOMATIC COLLATING AND SORTING MACHINE

Ballard Jamieson

Donald O. Lambert

Lynn L. Huffman

This publication describes a device which was designed to save manpower and reduce throughput time for distribution of multipage reports.

The counting and sorting of reports in accordance with a wide variety

of distribution lists had been previously performed as a separate

manual operation. It is now accomplished automatically and simultaneously with collating and stapling in a continuous operation.

Each type of report has an entirely different distribution list in

which (a) the number of copies required varies from one subscriber to

the next (b) not all of the list of subscribers receive all types of reports.

Each distribution bin is permanently assigned to a subscriber and

thus receives a variety of reports each with a different quantity but all

for the same destination.

To achieve this flexibility interchangeable plug boards are used

as programming elements, each board controlling the distribution of a certain type of report. The device comprises a commercially available

collator coupled to a newly developed rotatable table with a circular

array of bins.

In the figures, each relay is designated by K and a number, e. g. , Kl, and the contacts related to the relay are designated by the relay

number together with an additional numeral, e.g., 1-1, 1-2, and 1-3.

When one component is connected to another, a few leads are drawn

between the components and the remaining leads are illustrated by a few arrows directed between the components.
In Fig. 1, collator 20 collates and staples together sheets of

printed material to form documents which are deposited in bins 1 to 15

on table 21. Whenever a document is stapled a pulse, transmitted

from the collator, advances stepper switch 22 until the count programmed

for the bin is achieved. Current then flows through stepper switch 22,

program plug board 23 and stepper switch 24. This current activates

control circuit 25 to operate air motor 26 and indexing unit 27 until the

table is advanced to the point where collator 20 may deposit documents

into the next bin. When no documents are to be deposited in a bin, a pulse is transmitted through switch 22, plug board 23 and switch 24 to

operate pause control circuit 28 which inactivates the collator until the

table has been advanced to the following bin.

Signals are sent through diode matrix 30 to provide a visual

display on indicator 31 of the count of a document deposited in a bin.

Likewise, signals are fed from stepper switch 24 through plug board 23

to indicator 32 to display the number of documents programmed for a

bin, and signals are fed through diode matrix 33 to indicator 34 which

displays the number of the bin in which the documents are deposited.

Plug board 23 is shown in detail in Fig. 2. Each terminal in area IA represents the number of documents to be deposited in a bin,

and each terminal in areas IIA and IIIA represents the units and tens

digit, respectively, of such a number. The terminals in areas I, II, and III designate bin numbers.

A program is wired into the plug board by connecting each terminal

in I to a respective terminal in IA, depending upon the number of documents to be deposited in each bin. The terminals in area II are each

wired to a terminal in area IIA, while the terminals in area III are each

wired to a terminal in area IIIA, depending upon the units and tens

digits, respectively, in the number programmed for the related bin.
As an example, assume that bin 1 is positioned to receive documents from collator 20 and that 21 documents are to be deposited in

this bin. Then terminal 21 in area IA is wired to terminal 1 in area I in the plug board, as shown in Fig. 3, and the terminals 1 in areas II and III are wired to terminals 1 and 2 in IIA and IIIA, respectively. In

this way 21 documents are programmed in the plug board for bin 1.

Before the start of operation, arms 40 and 41 in banks I and II on

stepper switch 22 are resting on terminal in their respective banks.

At the same time, arms 43 and 44 in banks I and II of stepper switch 24

are on terminal 1 of their respective banks. When collator 20 staples

the first document relay K6, located in parallel with the stapler coil

(not shown) in the collator, is energized to close contacts 6-1. A

circuit is then completed through stepper coil 47, advancing arm 41 on

switch 22 to terminal 1. This process is continued until arm 41 engages

terminal 21 when a circuit is established through the pick coil of relay

Kl, plug board 23 and arm 43 of stepper switch 24 to ground. Relay Kl

is picked up and contacts 1-2 make (Fig. 4) to complete a circuit

through microswitch 52 to ground. Relay K2 is then energized and a holding circuit for this relay is established through contacts 2-3.

Contacts 2-1 (Fig. 3) make to energize stepper coil 4 8 and advance

switch 24. Contacts 2-2 (Fig. 4) close, setting up a circuit through

microswitch 55 to ground. Relay K7 is then activated and contacts 7-2

close, completing a hold circuit for the latter relay.

Contacts 7-1 close to complete a path that energizes solenoid 60,

and detent arm 63 is disengaged from a block (not shown) on the bottom

of table 21. There are fifteen detent blocks located around the bottom

of the table, one for each bin. As the detent arm moves out of the

engaged position, it closes microswitch 67, which completes a circuit

that energizes the pull solenoid valve 68 in air motor 69.
Air is admitted into cylinder 70 which pulls rod 71 and sliding

block 75 to the right in Fig. 4. As 75 moves to the right, spring 102

moves arm 98 downward and microswitch 55 is opened which breaks

the circuit through relay K7. Contacts 7-1 open and solenoid 60 is

released. Spring 80 then causes detent arm 63 to engage the block

on the bottom of table 21 associated with the next bin.

The rod pulls the sliding block to the right until the trigger pad

on latch 76 engages projection 77. When 77 is engaged the latch can

not move any further but the sliding block continues to move a short

distance, pivoting the latch so that pin 7 8 is disengaged. Spring 86

then forces the pin down, which trips microswitch 93. The pin is now

in the released position and 93 completes a circuit that energizes

solenoid 94. Air is now admitted into cylinder 70 in such a way that

rod 71 is pushed to the left in Fig. 4.

When pad 95 engages the plunger of microswitch 96, the microswitch completes a circuit that energizes solenoid 97. Arm 98 is then

pivoted upward, moving pin 78 into the recess in the block, associated

with the next bin, on the bottom of table 21. As the pin moves upward

the lower lip on latch 76 is pushed under the pin by leafspring 101.

Before the start of the example above, arms 40 and 41 (Fig. 3) are in their initial positions on terminals on banks I and II, respectively, of stepper switch 22. As the collator 20 staples its first document relay K6, connected in parallel with the stapler coil, is energized

to close contacts 6-1 and thus complete a circuit through stepper coil

47. Arms 40 and 41 are then advanced to terminal 1 on their related

banks. This process is continued until arm 41 engages terminal 21

when the circuit described in the paragraphs above is activated and

relay Kl is picked up. Contacts 1-3 then close to establish a circuit
through contacts 5-1 to energize the hold coil of relay Kl. Since

terminals 1 to 50 of bank. I, switch 22 are connected together a circuit

is creatd through contacts 1-1, self-homing device 100 and a stepper

coil 47. Arm 40 is then advanced until it engages terminal 51 when a

circuit is completed through the self-homing device to advance the arm

to terminal 0. A circuit is then established momentarily through timing

network 107 and relay K5 to pulse-open contacts 5-1, opening the

holding circuit for relay Kl. Contacts 1-1 break and the arms of switch

22 remain at rest on terminal of their respective banks.

If the number of documents required for a particular bin is zero,

a patchcord is connected between the bin's terminal in area I and

terminal in area IA of plug board 23 (Figs. 2 and 3). When arm 43 on

stepper switch 24 is advanced to the terminal representing the bin, a

circuit is completed to pick relays Kl and K8. Contacts 8-1 break and

since these contacts are connected in series with the drive motor of

collator 20 the motor is inactivated. Contacts 8-4 (Fig. 4) close,

picking up relay K2; contacts 2-1 make to complete a circuit through

coil 48 (Fig. 3) to advance the arms of stepper switch 24 to terminal 2. Contacts 2-2 close to energize relay K7, which in turn closes contacts

7-1 and starts the table advancing cycle described above. In this way

the table is advanced but no documents are deposited in the bin.

Each of the terminals in bank III (not shown) of stepper switch 22

are connected to diode matrix 30 (Fig. 1) which contains output circuits

connected to the respective terminals of a tens and units Nixie tube in

indicator 31. Thus when the arm of this bank is advanced in unison

with arm 41 on bank II, the selected tube elements are ignited to

indicate the count of the documents being deposited in a certain bin.
The terminals on bank II (Fig. 3) of stepper switch 24 are connected to diode matrix 33 which in turn has output leads connected

to each of the tens and units Nixie tubes 103 and 104 in indicator 34.

As the bins on table 21 are advanced to receive documents, arm 44 is

advanced around the terminals of bank II and the Nixie tubes are energized to display the number of the bin receiving documents.

Plug board 23 is wired to program the number of documents

required for each bin, and in the example above bin 1 is programmed

for 21 documents. When arm 44 is on terminal 1, bank II in switch 24

a circuit is established through the plug board to Nixie tube 105 to

display a "2" for the tens digit, while another circuit is completed

through the plug board to Nixie tube 106 to display a "1" for the units

digit. In this way "21" is displayed on the Nixie tubes in indicator 32.

10
OPTICAL HETERODYNE REFRACTOMETER

Lockett E. Wood

Moody C. Thompson, Jr.

11
OPTICAL HETERODYNE REFRACTOMETER

Lockett E. Wood

Moody G. Thompson, Jr.

31

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12
OPTICAL HETERODYNE REFRACTO METER

Lockett E. Wood

Moody C. Thompson, Jr.

This refractometer measures the optical refractive index of a thin (1 cm)

sample by projecting a laser beam through the sample and measuring

the phase shift between the incident and emergent beams. The measurement is facilitated by heterodyning the beams with laser light of

another wavelength. The light reflecting components of the refractometer are small and may be incorporated into a microwave cavity,

for example, to provide an optical-microwave dispersion measuring

system.

As shown in Fig. 1, the refractometer comprises a laser 10

arranged to project a light beam through a sample 12 whose refractive

index is to be measured. A retro-reflector 13 is positioned to return

the light through the sample 12, and beam splitters 14-15 and 16 are aligned to direct portions of the incident and emergent beams, respectively, to a pair of photomixers (photodetectors) 18 and 20. A second

laser 22 and a beam splitter 23 are arranged to project additional laser

light to the photomixers 18 and 20. The laser lights heterodyne and

the difference frequency components actuate the photomixers 18, 20.

The outputs of the photomixers 18, 20 are applied to a phasemeter 24;

the meter reading is the phase shift of the laser light traversing the

sample 12.

13
The phase shift cp indicated on phasemeter 24 is related to the

refractive index n of sample 12 by

nf T

where f is the frequency of the light from the first laser 10, L is the

total length of the light path through the sample 12, and c is the

velocity of light in vacuum. Hence, if laser 10 is a helium-neon laser

emitting light at 0. 6328 microns (f = 4. 76 • 10 Hz), and the sample

12 is 1 cm thick (L = 2 cm), a change in the refractive index n of one

part per million results in a phase change

A cp = — Anx 360° = 11. 4°.

The refractometer thus can easily measure the refractive indexes of

1 cm samples to better than 1 ppm.

In Fig. 1, the photomixer 18 and a stable intermediate-frequency

oscillator 26 are connected to a phase detector 28. The oscillator

frequency is equal to the nominal difference in the frequencies of

lasers 10 and 22. Thus, if the frequency of laser 22 drifts because

of thermal or other changes, the phase detector 28 produces an output

proportional to the drift. The output is applied to a piezoelectric or magnetostrictive mirror mount (not shown) in the laser 22; the mount

adjusts the laser resonant cavity in the direction to oppose the

detected frequency drift. In this manner, laser 22 is phase locked the

intermediate frequency away from laser 10, and the phasemeter 24 may

be sharply tuned to increase its sensitivity and simplify the measurement.

14
The sample 12 may comprise a gas flowing through a (transparent)

conduit, a liquid in a conduit or a container, or a solid in the form of a disc or plate.

If the accuracy of the phase shift measurement is to be high, the

laser path through the sample 12, the mountings of the four beam

splitters 14, 15, 16, and 23, and the frequency of laser 10 should be

stable during the measurement.

Fig. 2 shows the refractometer incorporated into a microwave

cavity 30. The cavity has three parallel, axially extending bores 31,

32 and 33, which are jointly intersected by a transverse bore 34. The

bore 31 extends into a side wall 35 of the cavity, bore 3 2 extends

through end wall 36, and bore 33 extends partly into the end wall 36.

The light from laser 10 is projected through bore 32, through the

gas in the microwave cavity 30, and is retro-reflected by prism 13

fitted into the far end wall 37. A beam splitter 38 disposed diagonally

across bore 32 directs a portion of the incident laser light up to photomixer 18, and a portion of the emergent light down to photomixer 20,

via a flat mirror 39. The light from laser 22 is projected into bore 31,

passes through the gas therein, and is returned by retro-reflector 40.

A beam splitter 41 directs part of the incident light down to photomixer

20, and part of the emergent light up to photomixer 18. The bore 31 is

hermetically sealed by three windows 42, and is evacuated or filled

with a dry reference gas.

The photomixers 18, 20 are connected to a phasemeter 24 as

in Fig. 1; the lasers 10 and 22 may be phase locked with the intermediate-frequency oscillator 26 and phase detector.

15
In the operation of the optical-microwave refractometer of Fig. 2,

the beams from lasers 10 and 22 are projected over identical paths

through the sample gas in the microwave cavity 30, and the vacuum or reference gas in bore 31, respectively. Portions of the incident and

emergent beams are paired, heterodyned, and applied to the photomixers 18 and 20; the phase difference of the photomixer outputs is a measure of the refractive index of the sample gas in cavity 30, relative

to the refractive index of the vacuum or reference gas in bore 31.

Simultaneously, the cavity 30 is supplied with variable frequency

microwave energy in the well-known manner, and the resonant frequency

of the cavity is determined and related to the microwave refractive

index of the sample gas in the cavity. From the resultant optical and

microwave refractive indexes, the dispersion of the sample gas at the

frequencies of laser 10 and the microwave resonance may be determined, as known in the art.

The dispersion measurement provided by the refractometer of

Fig. 2 provides a convenient, precise method of determining the water

vapor content of an atmospheric sample in the cavity 30. It is well

known that the difference between the optical and microwave refractive

indexes of moist air is in the order of 100 ppm. Since the refractometer

resolves these indexes to better than 1 ppm, the water vapor can be

determined easily and directly within a few percent.

In Fig. 2, the optical components (beam splitters 38, 41, mirror

39, prisms 13,40, and windows 42) are arranged symmetrically in the

walls of the microwave cavity. This makes many of the dimensional

changes in the spacings of the components, due to temperature or other

changes, balance or cancel each other. In addition, the usual temperature compensations employed in the microwave cavity tend also to

compensate the optical system.

16
LIQUID METERING PUMP

Walter D. Komhyr

17
LIQUID METERING PUMP

Walter D. Komhyr

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LIQUID METERING PUMP

Walter D. Komhyr

This pump relates to the class of pumps utilizing a rolling compression

along a flexible tube. It eliminates leakage usually associated with

such pumps, and in addition is self-adjusting, trouble-free, and

economical.

As shown in Figs. 1 and 2, the pump housing comprises a base

plate 10, an integrally-formed back plate 11, and a front plate 12

that is spaced from and secured to the back plate 11 by cylindrical,

threaded-through spacers 13, screws 14, and nuts 15. The back plate

11 mounts a small geared motor 16, the shaft 17 of which is connected

to a pump shaft 18 by a recessed set screw 19. The pump shaft 18 is

journalled in an annular bushing 20, preferably of Teflon, that is

attached to the front plate 12 by screws 21. A section of flexible

tubing 22 of silicone rubber or the like is wrapped around the bushing

20 and suitably cemented to the front plate 12. The ends of the tubing

22 extend through holes 23 provided in plate 12, and are anchored in a clamp 30. The ends provide the inlet and outlet of the pump.

The pump shaft 18 is slotted, as shown best in Fig. 3, to slidably receive an axle 24 having a flattened midportion 25. The axle 24

slidably and rotatably carries a pair of rollers 26, preferably Teflon,

which are retained on the axle by washers 27 and screws 28. The axle

24 is slightly longer than the diameter of the bushing 20 plus the

lengths of the rollers 2 6, so that the rollers 26 are freely guided by

the cylindrical surface of the bushing 20 to overlay the tubing 22. The

rollers 26 compress the tubing 22 against the front plate 12 by virtue

of a helical spring 29 disposed about the pump shaft 18 between the

axle 24 and back plate 11. A Teflon washer 31 is provided between the

spring 29 and plate 11 to reduce the friction therebetween as spring 29

rotates with the pump shaft 18 and axle 24.

19
As shown in Fig. 2, the surface of the bushing 20 adjacent the

axle 24 comprises upper and lower parallel planar portions 32 and 34,

and a pair of interconnecting ramps 36. The upper or raised portion 32

extends over an arc that includes the ends of the tubing 22 (apertures

23), and provides a support for the axle 24 when the associated roller

26 traverses the end portions. This supporting action is clearly shown

in Fig. 1. The ramps 36 smoothly guide the axle 24 onto and off the

raised portion 32 so that the associated roller 26 effects a correspondingly smooth release and compression of the tubing 20. In this manner,

the rotation of the axle 24 by motor 16 is free from the vibration that

would otherwise ensue from the transfer of the rollers 26 across the

ends of the tubing 2 2; and the flow of liquid effected by the rolling

compressions of the rollers 26 on the tubing 22 is smooth and free of

pulsations that cause back-leakage of the pumped fluid. This latter

feature is especially important when the pump is used to precisely

meter liquids in medical instruments, chemical analyzing apparatus,

and the like. Furthermore, it will be apparent that the construction of

the bushing 20, slidable axle 24 and slotted pump shaft 18 is rugged,

reliable, self-adjusting, and economical to fabricate and assemble.

The inexpensive, lightweight, but rugged characteristics of the pump

are especially adapted to portable and airborne chemical analyzer

instrumentation requiring continuous metering or replenishment of

reagent solution.

20
STABLE WIDEBAND RELAXATION OSCILLATOR USING

THREE INVERTING AMPLIFIERS

Rufus E. Gordon

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STABLE WIDEBAND RELAXATION OSCILLATOR USING

THREE INVERTING AMPLIFIERS

Rufus E. Gordon

This relaxation circuit oscillates over a range extending from less

than one Hz to several MHz, and is relatively insensitive to temperature changes.

As shown in Fig. 1, the oscillator comprises three cascaded

inverting amplifiers 10, 12, and 14. A capacitor 16 is connected

around amplifiers 10 and 12, and a resistor 18 is connected around

all three amplifiers 10, 12, and 14. The oscillator output 20 is

taken from the output of amplifier 12.

In the operation of the oscillator, when the input to amplifier 10

is low, its output is high, the output of amplifier 12 is low, and the

output of amplifier 14 is high. In this condition, capacitor 16 charges

through resistor 18, as illustrated by the charging curve 22 of the

voltage curve V,

fi

, Fig. 2, which represents the voltage across

capacitor 16. The voltage V,

fi raises the input to amplifier 10, and

eventually reaches the amplifier turn-on point, causing the output of

amplifier 10 to go low, and the outputs of amplifiers 12 and 14 to

change state. As the output of amplifier 12 changes state from the low

value 24 to the high value 26 (see V20 in Fig. 2), capacitor 16 provides

regenerative feedback to the input to amplifier 10, causing the input

to rise sharply as shown at 2 8 of V-,

fi in Fig. 2. After the amplifiers

change state, capacitor 16 discharges through resistor 18, as illustrated at 30 in Fig. 2. This continues until the turn-off point of

amplifier 10 is reached, and all of the amplifiers again change state,

22
as indicated at 32 and 34 in Fig. 2. Thus the output voltage V

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taken from amplifier 12 provides a very clean rectangular wave having

a frequency approximately equal to

^ -^— . The frequency may be

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18 °16

varied by varying resistor 18 or capacitor 16, or both. If presentlyavailable digital integrated circuit inverting amplifiers (NOR gates,

etc.) are used at 10, 12, and 14, the circuit will oscillate from less

than one Hz to six MHz or better.

The frequency stability of the present oscillator is very good

because the period is determined by the sum of the times 22 and 30

of V,

fi

. As the turn-on and turn-off points, which are essentially

the same, vary with temperature, time 22 will increase while time 30

decreases or vice versa. Since the slope of one curve increases as

the other decreases the compensation is not perfect, but nearly so if times 22 and 30 are nearly equal. This inherent characteristic of the

circuit achieves high frequency stability without the use of conventional, expensive compensating means. The symmetry of the rectangular

wave is disturbed slightly but the period and frequency remain nearly

constant over a wide temperature range.

23
SEAT BELT WEBBING ABRASION RESISTANCE TESTING MACHINE

Alfred B. Castle, Sr.

M<r. i

Fzcr.2

24
SEAT BELT WEBBING ABRASION RESISTANCE TESTING MACHINE

Alfred B. Castle, Sr.

This machine comprises a modified, balanced version of the standard

machine set forth in 15 USC 9. 7(d), and published in the Federal

Register , Vol. 31, No. 169, Part II, pages 11531 and 11536, on

August 31, 1966, entitled Standards for Seat Belts for Use on Motor

Vehicles.

As shown in Figs. 1 and 2, the machine includes a lightweight

drum 10 formed from a pair of rigid, semicircular end plates 11, a thin

curved sheet 12, and a pair of longitudinal stiffening members 13. The

end plates 11 carry centrally-disposed shafts 14 which are journalled

in suitable bearings mounted in a frame (not shown) for the machine.

The front end plate 12 also carries an eccentrically positioned shaft 15

which is connected by a crank arm 16 to a crank 17. The crank 17 is

driven by an electric motor (not shown) secured to the machine frame.

In this manner, the rotation of the crank 17 by the motor effects an

oscillation of the drum 10, as indicated by the arrow 18. The dimensions of the crank 17, the offset of the shaft 15, and the diameter of

the drum 10 are selected to provide an oscillation stroke of 13 inches,

as specified in the above-mentioned Sec. 9. 7(d) of Title 15. The

motor speed is such as to provide the proscribed 60 ± 2 strokes per

minute.

The machine further includes a pair of hexagonal steel bars 20,

of the type specified in Sec. 9. 7(d). These bars are supported by

slotted angle brackets 19 secured to the machine frame so that the bars

are aligned parallel to the longitudinal axis of drum 10, and slightly

above the bottom of the drum on opposite sides thereof. The ends of

the bars 20 carry (equilateral) triangular end pieces 21 which key with

25
the angle brackets 19 to position one of the three pairs of edges of the

bars to receive a plurality of seat belt webbings 22 to be abraded. The

webbings 22 are releasably secured to the drum 10 by metal straps 23,

and thumbscrews 24 threaded into the longitudinal stiffening members

13 of the drum. Successive webbings 22 are secured alternately to

the right and left sides of the drum, passed under the drum, and over

the hexagonal rod 20 on the opposite side of the drum. A plurality of

weights 2 5, each having the mass called for by Sec. 9. 7(d), are attached to the remaining ends of the webbings. An even number of

webbings are used, such as the six webbings 2 2 that are illustrated,

so that the resulting torques on the drum 10 are evenly distributed and

balanced along the length of the drum.

The above-mentioned Sec. 9. 7(d) specifies that each webbing

shall be abraded over two new edges of the hexagonal bars 20. Accordingly, when a pair of new bars 20 are placed in the angle brackets 19,

the numbered faces of the end pieces 21 facing the operator (see

numberals "2" on pieces 21 in Fig. 2) are recorded. A set of webbings

22 are then attached to the drum 10, the weights 2 5 attached thereto,

and the drum oscillated for 2, 500 cycles, after which the webbings

are removed and tested in conformance with Sec. 9. 7(d). The next

set of webbings are then attached to the drum 10 in a pattern that is the

reverse of the preceding pattern. For example, in Fig. 2 the front

webbing 22 is attached to the left stiffening member 13; in the next

test, the front webbing would be attached to the right stiffening

member, the successive webbings being alternated left and right to

form the desired alternately spaced pattern. In this way, the second

set of webbings would contact the hexagonal bars 20 along the portions

that were not used (rubbed) by the first set of webbings. For the third and

26
fourth sets of webbings, the bars 20 would be rotated to cause the

second faces of the end pieces 21 to face the operator, and the webbings would be arranged in the two patterns Just described. Finally,

two more sets of webbings could be tested by rotating the bars 20 to

the third positions of end pieces 21, after which it would be necessary to replace the bars 20.

From the foregoing it will be seen that the present machine

greatly facilitates the testing of a large number of seat belt webbings

for their resistance to abrasion. The machine permits the operator to

test a large number of webbings simultaneously, without imposing an

unbalanced load on the motor of the machine. The hexagonal abrading

bars require a rotation only after the second and fourth tests, and

replacement after the sixth test, thereby reducing the number of manipulations required of the operator. In addition, the numbered end pieces

21 on the bars 20 enable the operator to quickly record, for future

references, the abrasion bar used to test a given set of set belt

webbings.

ftU. S. GOVERNMENT PRINTING OFFICE: 1967 —301-021/55 27

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