ID: nht74-2.42

DATE: 08/07/74

FROM: AUTHOR UNAVAILABLE; R. B. Dyson; NHTSA

TO: Royal Industries

TITLE: FMVSS INTERPRETATION

TEXT: This responds to your July 23, 1974, question concerning the certification responsibility of a small manufacturer of trailers that must conform to Standard No. 121, Air brake systems. You ask if road testing of any or all vehicles produced would be necessary to satisfy the requirements.

A manufacturer must "exercise due care" in certifying that the vehicles manufactured by him comply with the applicable standards (National Traffic and Motor Vehicle Safety Act of 1966, @ 108(b)(2), 15 U.S.C. @ 1392(b)(2)). What constitutes due care in a particular case depends on all relevant facts, including such things as the time to elapse before a new effective date, the availability of test equipment to small manufacturers, the limitations of current technology, and above all the diligence evidenced by the manufacturer.

A small manufacturer of standard and custom trailers might fulfill his due care responsibility to assure that each of his trailers is capable of meeting the standard in several ways. For example, he could establish categories of models which share a common brake and axle system and certify them all on the basis of tests on the most adverse configuration in the category. Calculations should be written down in such a case to establish that reasonable care was taken in these decisions.

Alternatively, joint testing might be undertaken with a trade association or with a major supplier of brake and axle components. In the case of standard models, you might be able to rely on the supplier's warranty of his products' capacities.

Neither of these methods would require road testing of each vehicle manufactured, nor would every model have to be road tested. A manufacturer must simply satisfy himself that the trailer is capable of meeting the stopping performance requirements if it were tested by the NHTSA.

Yours truly,

ATTACH.

PEERLESS DIVISION ROYAL INDUSTRIES

July 23, 1974

Chief Council -- National Highway Safety Administration

Dear Sir:

This concerns a recent telephone conversation between Loretta Carlson of the National Highway Safety Administration in Seattle and myself.

As a custom trailer manufacturer, we seldom manufacture any number of trailers of the axact same model. While we may build saveral trailers a year to perform the same job, there could be sufficient change from order to order that could conceivably classify them as different models.

My question of her was whether or not we, as a custom commercial trailer manufacturer, would be required to road test all models of trailers that we build to meet the requirements of FMVSS121.

Loretta Carlson talked to your office and relayed your answer to me in that for a manufacturer to satisfy the requirements of FMVSS121, he has to exercise due care to certify his equipment as meeting the requirements of FMVSS121.

Also, your office felt that if we road tested a trailer that we felt would be the worst configuration to meet the requirements of FMVSS121, then we could be considered as exercising due care.

I am very grateful for the assistance of Loretta Carlson and would greatly appreciate a letter from your office confirming your conversation with her on this matter.

C. J. Baker -- Research & Development Engineer

ID: nht74-2.43

DATE: 05/24/74

FROM: AUTHOR UNAVAILABLE; R. B. Dyson; NHTSA

TO: Dorsey Trailers

TITLE: FMVSS INTERPRETATION

TEXT: This responds to your May 3, 1974, question concerning the certification responsibility of a manufacturer of trailers that must conform to Standard No. 121, Air brake systems. You ask if the substitution of parts not specified by an axle manufacturer will affect certification if the parts are nearly identical in their specifications and performance to the recommended parts.

In the case of substitution of parts, you must simply satisfy yourself that your vehicles are capable of meeting the requirements of the standard in a test by the NHTSA. If you are satisfied that the supplier's recommended package will meet the requirements, and you determine that a substitution would not adversely affect the vehicle's performance to the point where it no longer would meet the requirements, you are free to make the substitution. It would be advisable to make some record of your calculations of the effect of such substitutions.

Yours truly,

ATTACH.

May 3, 1974

James B. Gregory, Administrator -- National Highway Traffic Safety Administration

Dear Sir:

Dorsey Trailers, Inc. has selected Wagner Electric Corporation and The Berg Manufacturing Company to supply the air actuation and anti-skid equipment for all trailers manufactured by this company. Other companies have been reviewed as suppliers on special customer request but our Engineering and Production techniques are only developed for the above two suppliers at this time. Both of the suppliers have assured us of adequate inventory of the required material to start shipping trailers by September 1, 1974 with the F.M.V.S.S. 121 specifications.

The two major axle suppliers which we use, Kershaw Axle Division of C. & M. Spring Company and Standard Forg and Axle Company, have both promised axles with brakes to meet the 121 specifications by September 1, 1974.

The problem that concerns us is the dynamometer brake rating. We have just been given a new interpretation of the requirements for the dynamometer rating, stating that if any portion of the combinations of components such as air chambers, slack adjusters, brake drums, etc. is changed from the exact specified part number and brand name used in certifying an axle with a given brake lining, the certification is voided and not acceptable. If this is true, then there does not seem to be enough dynamometer time available to meet a deadline even by January 1, 1975 for all combinations of parts available to the trailer industry.

As a smaller manufacturer of trailers we do not enjoy the luxury of telling our customers that certain parts are our standard materials and we won't furnish other components. Our customers usually have their own part specifications to simplify their maintenance.

If we had an axle certified with B-W slack adjusters, 6" long and B-W type 30 spring brake chambers, but our customer specified his axles must have Berg 6" slack adjusters and Berg Type 30 spring brake chambers, would this affect the certified axle? The substitution would be of equal parts and performance but different brand names.

Another example would be an axle certified with a Webb #66518 drum weighing 96 pounds and the customer specifying a Webb #67518 drum which weighs 106 pounds. The addition of the 10 pounds of weight would increase the fade-away characteristics by better heat dissipation but would this change require another dynamometer test?

Some customers specify cast brake shoes while others prefer fabricated brake shoes. With all other components being the same, would the change in brake shoes require a new certification?

If our suppliers meet their commitments, we could offer certain of our options to meet "121" specs on September 1, 1974. To certify all of the options that we are required to furnish, there could possibly not be enough dynamometer time available by January 1, 1975. Please give us an interpretation on varying the components and how this would effect the certifications.

Due to material shortages, the privilege of switching suppliers of certain assemblies is almost prohibitive since allocation of material is very common. This problem will only multiply the above problem of dynamometer testing time. If your regular supplier does not have his own dynamometer, it will be very difficult to secure time on an independent test machine and impossible to get the service of your competitors' equipment.

Yours very truly,

DORSEY TRAILERS; Roy C. Belcer - Vice President -- Manufacturing and Engineering

CC: G. L. Collier

ID: nht74-2.44

DATE: 05/11/74

FROM: AUTHOR UNAVAILABLE; Richard B. Dyson; NHTSA

TO: The Adams & Westlake Company

TITLE: FMVSS INTERPRETATION

TEXT: This is in reply to your letter of March 13, 1974, asking whether S5.3.2 of Motor Vehicle Safety Standard No. 217, "Bus Window Retention and Release," permits the use of more than one release mechanism on any one opening if each mechanism requires a separate motion to release.

Standard No. 217 does not prohibit the use of more than one separate release mechanism for a single opening. However, S5.3.2 does limit to two the number of total force applications, and this limits the number of separate release mechanisms to two. If two release mechanisms are used, each must be operated by only one force application, and one of these force applications must differ by 90 degrees to 180 degrees from the direction of the initial push-out motion of the emergency exit.

Of course, in using this configuration, the other requirements pertaining to emergency exists and release mechanisms in Standard No. 217 must also be met.

YOURS TRULY,

March 13, 1974

Office of Chief Consul National Highway Traffic Safety Administration

Attention: Mr. Larry Schneider

In regards to Motor Vehicle Safety Standard #217, "Bus Window Retention & Release", please refer to S5.3.2 which states:

"The release mechanism or mechanisms shall require for release one or two force applications."

Is this to be interpreted that more than one mechanism, each requiring a separate motion to release, can be used on any one opening?

This question is prompted by reason of a car body structural member, at center line of rear window opening, which makes a single mechanism unsuitable.

Your earliest reply will be appreciated.

Earl V. Gordon -- Manager of Engineering, THE ADAMS & WESTLAKE CO.

cc: H. C. Gildner, Vice-President, Transportation Sales; C. M. Miller, Vice-President, Engineering

ID: nht74-2.46

DATE: 12/04/74

FROM: AUTHOR UNAVAILABLE; Andrew G. Detrick; NHTSA

TO: Matlock Truck Body and Trailer Corporation

TITLE: FMVSR INTERPRETATION

TEXT: This is in reference to your defect notification campaign (NHTSA No. 74-0203) concerning trailers equipped with Standard Forge axles which may have defective brake shoes.

The letter which you have sent to the owners of the subject trailers does not completely meet the requirements of Part 577 (49 CFR), the Defect Notification regulation. Specifically, the second sentence of your letter describes the defect as existing in the brake shoes. Part 577.4(b), however, requires that in cases where a vehicle manufacturer is notifying owners of vehicles, the letter must state that a defect exists in the vehicle itself. The reference to motor vehicle equipment applies only to equipment campaigns where vehicles are not directly involved. Your letter also fails to adequately evaluate the risk to traffic safety as required by Part 577.4(d) since it does not state that the vehicle crash without warning may occur. Although the statement that reduced braking power or lockup may result may suggest the possibility of a crash to many owners, it is not entirely adequate.

Although mailing of a revised notification letter will not be required, it is expected that in the event that another defect notification campaign ever becomes necessary in the future, the notification letters conform completely with the regulations.

A copy of Part 577 is enclosed. If you desire further information, please contact Messrs. W. Reinhart or James Murray of this office at (202) 426-2840.

Sincerely,

Andrew G. Detrick -- Acting Director, Office of Defects Investigation Motor Vehicle Programs

Enclosure

ATTACH.

MATLOCK TRUCK BODY & TRAILER CORP.

February 11, 1975

Wolfgang Reinhart -- Office of Defects Investigation Motor Vehicle Programs, U.S. Department of Transportation, National Highway Traffic Safety Administration

RE: N41-62 re

Dear Mr. Reinhart: I received Mr. Andrew G. Detrick's letter of December the 4th, 1974 in regard to our defect notification campaign (#74-0203). He stated that my letter did not completely meet the requirements of Part 577 (49 CFR) in two specific items. I am returning a copy of his letter with the two points in question underlined in red and marked 1 and 2. Also, I am enclosing a copy of my letter of defect notification with the "answers" underlined in red and marked 1 and 2.

Please note that in the point marked 1 that my letter states that the defect exist in the brake shoes on Matlock MTE (electronic trailers).

In the second point, perhaps we were not specific enough about the possibility of a crash, but we were only quoting the statement in Standard Forge's letter to us.

We sent all the information to Standard Forge concerning the recall after receiving a letter from Mr. Detrick on January the 6th, 1975. In accordance with his letter, we will not submit the quarterly reports. A copy of the letter to Standard Forge is also enclosed.

Yours truly,

Curtis Eddy Vice President - Engineering

This notice is sent to you in accordance with the requirements of the National Traffic and Motor Vehicle Safety Act.

Matlock Truck Body and Trailer Corporation has determined that a defect which relates to motor vehicle safety exists in the brake shoes of Standard Forge axles with 12 1/4" x 7 1/2" brakes on Matlock Model MTE (electronic trailers). These axles are used only with 15" wheels and on trailers produced between February 1, 1974 and October 31, 1974.

Standard Forge and Axle Company, one of the world's largest manufacturers of trailer axles, made a change in the brake shoe attachment on some of the axles made for highway trailers early in 1974. After several months of operation, some of these axles have caused brake problems.

Standard Forge has been very prompt in their actions to correct any problems of approximately 5000 axles that are involved. Matlock received only 438 of these axles or about 9%. The other 91% have gone to others, including most of the leading trailer manufacturers.

The axles concerned are only those with 15" wheels with 12 1/4" x 5 1/4" or 12 1/4" x 7 1/2" brakes. Matlock uses only the heavier 12 1/4" x 7 1/2" brakes. If you have a trailer other than a Matlock, as a safety precaution, you might check the brakes yourself or contact your trailer supplier.

Approximately 200 of the 438 axles supplied to Matlock have been corrected already, or are in our plant and will be corrected prior to shipment of new trailers.

For your information, a copy of the letter from Standard Forge alerting trailer companies of a possible problem is enclosed.

The second paragraph of Standard Forge's letter explains the condition that might cause the malfunction and the result of such an occurance. Note that breakage can occur without warning, resulting in reduced braking power or lockup.

We instruct you to remove from service immediately any trailer that has an axle in the list that follows until the brake shoes can be replaced.

Also enclosed is a drawing showing both the correct and incorrect brake shoes. The casting number on the brake shoe will be 201103 on both the correct and incorrect brake shoe. However, the two can be easily distinguished by the shape of the end of the brake shoe. The ones that should be replaced have had the ends milled off; the replacement, or newer parts, have a closed end.

Matlock is attempting to do everything possible to minimize any inconvenience to you. Your cooperation will be appreciated. Please follow the procedure as outlined below:

1. Check the serial number on each axle used with 15" wheels. The serial number is located in the center of the axle on the name tag. If it is a Standard Forge axle and has one of the serial numbers in this list, the brake shoes should be checked and changed if they are the incorrect brake shoes. Some of the axles in this list, however, have already had the brake shoes replaced. If the brake shoes are the correct type on one end of the axle, it will not be necessary to pull the drums on the other end. We will allow one and one-half (1 1/2) hours labor per axle for checking only. In order to be reimbursed for this labor, you MUST send us the trailer serial number and the axle serial number. Be sure that the axle serial number is contained in this list, as we will not pay for labor for axles not contained in this list. 14074 thru 14083 33207 thru 33242 20199 " 20212 34011 " 34035 20213 " 20226 34036 " 34060 24535 " 24634 34111 " 34210 25128 " 25137 36406 " 36465 25348 " 25357 42395 " 42494 27572 " 27589 46360 " 46365

NOTE: If you have a Matlock trailer with 15" wheels, and you cannot read the serial number on the axle, pull the brake drum on one side of each axle to be sure that you do have brake shoes that are the correct type.

2. You may bring your trailer to our plant in Nashville or to our branch in Knoxville for the required rework. You may do the work in your own shop, or you may take it to any reputable trailer repair shop such as, but not limited to, Dorsey, Fruehauf, Great Dane, Lufkin, Nabors, Strick, Timpte, Trailmobile, or Utility. If you have any question as to where you should take your trailer for repair, you may call Mr. Jim Waters of Standard Forge and Axle Company, in Montgomery, Alabama, (205) - 269-1271.

3. The replacement parts are available now and should be ordered from Matlock Truck Body and Trailer Corporation, 1070 Visco Drive, Nashville, Tennessee 37210 - (615) - 259-2000.

The replacement parts will be shipped and invoiced to you at regular parts prices. We will allow up to five (5) hours labor per axle to replace these parts, although we believe that four (4) hours will be sufficient in most cases. Oil seats will be furnished and must be replaced.

You will be given full credit for parts, labor and freight both ways when the parts that are replaced are returned to us in Nashville, freight prepaid. The parts should be returned to the above address and marked to the attention of Mr. Tom Hartigan.

IMPORTANT: All parts returned MUST have the trailer serial number and the axle serial number on the shipping crate and on your invoice to us.

If you have sold or otherwise disposed of a trailer that was built between February 1, 1974 and October 31, 1974, please send us the name and address of the buyer or the disposition of the trailer.

We want to tell you that when you deal with Matlock, you are dealing with a reliable supplier that wants to correct this safety defect. We appreciate your business and would like to take this opportunity to solicit your order for the coming year for your trailer and truck body needs.

Yours truly,

Curtis Eddy Vice President - Engineering

ID: nht74-2.47

DATE: 08/27/74

FROM: Frank Berndt; NHTSA

TO: Armstrong Rubber Company

TITLE: FMVSR INTERPRETATION

TEXT: This will confirm that the suggested defect notification letter, enclosed in your letter of August 14, 1974, meets the requirements of 49 CFR Part 577.

We appreciate your taking this action with respect to the Steel Belted Surveyor 78 tire.

ID: nht74-2.48

DATE: 07/26/74

FROM: AUTHOR UNAVAILABLE; E. T. Driver; NHTSA

TO: Stanley Electric Co., Ltd.

COPYEE: L. OWEN

TITLE: FMVSS INTERPRETATION

TEXT: This is in reply to your letter of July 11 in which you asked what standards will be applied to stop and turn signal lamps after September 1, 1974.

Parking, stop, and turn signal lamps are required by Section S4.1.1.11 and S4.1.1.12 to meet the grouped photometric minimum candlepower requirements specified in Figure 1 of FMVSS No. 108. Prior to September 1, 1974, multiple compartment or multiple lamps need only meet the group value total specified in Figure 1 for a single compartment or single lamp. After that date, however, the higher candlepower values for two and three compartments or lamps specified in Figure 1 are applicable.

Docket 69-19; Notice 3, published in the Federal Register on October 25, 1972, only proposed that SAE (Illegible Word) and (Illegible Word) be referenced in FMVSS No. 108. Until such time as Standard 108 is further amended, SAE J586b, June 1966, and J588d, June 1966, are applicable to stop lamps and turn signal lamps, respectively.

If the new revisions to the SAE standards are included as an amendment to Standard 108, sufficient lead time will be provided to allow the manufacturers to make any changes necessary to meet the new requirements.

Sincerely,

Not Controlled

ATTACH.

STANLEY ELECTRIC CO., LTD.

July 11, 1974

E.T. Driver -- Director Office of Operating Systems Motor Vehicle Programs,

U. S. Department of Transportation, National Highway Traffic Safety Administration

Re: A lamp with two or three lighted compartments used in Stop Lamp and Turn Signal Lamp.

Dear Mr. Driver

According to S 4.1.1.12 in MVSS No. 108 a lamp with two or three lighted compartment is required to meet the minimum photometoric values at each test point specified in table 2 of SAE Standard J575d.

However, after September 1, 1974 a Stop Lamp has to be complied with SAE J586c by P.R. dated October 25, 1972 and SAE J508e for Turn Signal Lamp and further the standards of a lamp with two or three lighted compartments will be applied to a lamp with two or three lighted compartments and by F.R. dated April 9, 1974 the F.R. dated October 25, 1972 has been postponed.

Please let us know what standards will be applied to Stop, Turn Signal Lamp after September 1, 1974, the standards as they are now or the proposal as it is being planned will become effective.

Thanking you in advance for your cooperation,

Very truly yours, H. MIYAZAWA -- Director, Automotive Lighting, Engineering Dept.

ID: nht74-2.49

DATE: MAY 24, 1974

FROM: ALFRED TEVES

TO: JAMES B. GREGORY -- ADMINISTRATOR-NHTSA

TITLE: INTERPRETATION OF FMVSS NO. 105-75

ATTACHMT: OCTOBER 3, 1988 LETTER FROM JONES TO BURKARD, EBNER, AND TEVES, FEBRUARY 3, 1981 LETTER FROM KAWANO TO BERNDT, JULY 10, 1974 LETTER FROM DYSON TO NAKAJIMA, MAY 27, 1988 LETTER FROM TEVES TO JONES, AND OCTOBER 9, 1988 LETTER FROM JONES TO BURKARD, EBNER, AND TEVES

TEXT: We wish to request clarification of our interpretation of S5.4.1, Master Cylinder Reservoirs, of FMVSS No. 105-75, (105a) published in the Federal Register on May 18, 1973.

S.5.4.1 reads as follows:

Master Cylinder Reservoirs.

A master cylinder shall have a reservoir compartment for each service brake subsystem serviced by the master cylinder. Loss of fluid from one compartment shall not result in a complete loss of brake fluid from another compartment.

As we understand it, this Section does not prohibit the designs sketched below.

See Illustration on Original

F: Front

R: Rear

C: Clutch

ID: nht74-2.5

DATE: 11/04/74

FROM: AUTHOR UNAVAILABLE; R. B. Dyson; NHTSA

TO: Todco Division

TITLE: FMVSS INTERPRETATION

TEXT: This responds to Todco's September 27, 1974, question whether Standard No. 121, Air brake systems, 49 CFR 571.121, requires a spring brake system on Todco's "Jifflox converter dolly." You describe the Jifflox dolly as a trailer converter dolly which may also be used as a "third axle attachment" on a two-axle truck.

Standard No. 121 applies to vehicles, and specifies separate requirements for trucks, buses, and trailers. It appears that the Jifflox is subject to separate requirements under the standard depending on its use.

If Todco manufactures (Illegible Word) sells the Jifflox for use as a "trailer converter dolly" (defined in 49 CFR 571.3 as a trailer equipped with one or more axles, a lower half of a fifth wheel, and a drawbar), it constitutes a vehicle subject to Standard No. 121. As such it is exempted from the parking brake system requirements (S5.6) and its emergency braking capability is not required to be applied by an emergency source, such as a spring brake, that is not affected by loss of air pressure or brake fluid pressure in the service brake system.

If a truck manufacturer utilizes the Jifflox as an additional axle in the suspension of its vehicle, the truck manufacturer must assure that the truck meets the requirements applicable to it with the Jifflox incorporated in it. This means that, if the truck is manufactured to accept the Jifflox dolly and the truck is rated for a gross vehicle weight rating that depends on inclusion of the axle, the truck must comply with all applicable requirements of the standard with the Jifflox attached. If the truck manufacturer determines that parking brakes are required on the Jifflox axle to meet S5.6.1 or S5.6.2, those parking brakes would have to be applied by an energy source that is not affected by loss of air pressure or brake fluid pressure in the service brake system.

Yours truly,

ATTACH.

September 27, 1974

Richard Dyson -- Chief Council, National Highway Traffic Safety Administration

Dear Mr. Dyson:

This is a second request regarding a ruling on the Jifflox Converter Dolly. This letter is in lieu of our first request of which our copy has been misplaced.

The Jifflox Converter Dolly has been manufactured, sold and licensed as a converter dolly. As stated in F.M.V.S.S.-121 paragraph S.5.8 a converter dolly need not have spring brakes. However, the Jifflox is unique in the fact that it can also be used as a third axle attachment.

In previous conversations with Mr. Sid Williams it has been his opinion that since the Jifflox is sold and licensed as a converter dolly it would be exempt from spring brakes. He reffered us to your office for an official ruling.

Since we deal directly with the truck manufacturers they are obviously concerned with this ruling. They have in fact requested from us an official ruling from your office.

I would think that since the Jifflox is sold throughout the United States, an ammendment to F.M.V.S.S.-121 would be in order. However an official ruling from your office in letter form would suffice.

Since we are a member of the T.T.M.A., I am forwarding a copy of this letter to Mr. Bert Weller, in hopes that research in this matter may be expedited.

If you have any questions regarding this matter, do not hesitate to contact me.

Sincerely

Frank L. Wigand, Eng. Dept. -- TODCO Division

cc: Joseph J. Cunha; Bert Weller

ID: nht74-2.50

DATE: 07/10/74 EST

FROM: RICHARD B. DYSON -- NHTSA ASSISTANT CHIEF COUNSEL

TO: K. NAKAJIMA -- DIRECTOR/GENERAL MANAGER, FACTORY REPRESENTATIVE OFFICE - TOYOTA

TITLE: N40-30

ATTACHMT: OCTOBER 9, 1988 LETTER FROM JONES TO BURKARD, EBNER, AND TEVES, OCTOBER 9, 1981 LETTER FROM BERNDT TO KAWANO, FEBRUARY 3, 1981 LETTER FROM KAWANO TO BERNDT, MAY 24, 1974 LETTER FROM TEVES TO GREGORY, AND MAY 27, 1988 LETTER FROM TEVES TO JONES

TEXT: This is in reply to your letter of May 24, 1974 to Dr. Gregory asking whether the five master cylinder reservoir designs indicated would meet the requirements of S5.4.1 of Motor Vehicle Safety Standard No. 105-75.

Each of these designs appears to conform to S5.4.1 providing that the reservoir capacity requirements of S5.4.2 are met. It appears that Designs (3) and (4) would require additional fluid for the clutch.

ID: nht74-2.6

DATE: 09/26/74

FROM: AUTHOR UNAVAILABLE; R. B. Dyson; NHTSA

TO: Eagle International Inc.

TITLE: FMVSS INTERPRETATION

TEXT: This responds to your July 16, 1974, request for approval of the Bendix "dual circuit air brake system" for use on your buses in satisfaction of Standard No. 121, Air brake systems. In a subsequent phone call with Mr. Herlihy of this office, you stated that your only concern was whether the standard requires a parking brake system that meets the axle-by-axle retardation force requirements of S5.6.1 and the grade holding requirements of S5.6.2.

The National Highway Traffic Safety Administration is unable to "approve" plans or prototype systems for compliance with a standard in advance, because there is no way to establish that a vehicle so equipped actually meets the requirements until it has been manufactured.

With regard to your specific question, S5.6 states that each vehicle shall have a parking brake system that meets the requirements of S5.6.1 or S5.6.2 at the manufacturer's option. This means that you are free to choose a system which meets either of these requirements but does not meet both.

Yours truly,

ATTACH.

July 16, 1974

Sid Williams; 400 7th Street, S.W.; Washington, D.C. 20024

Dear Sid:

Enclosed is a copy of our Dual Circuit Air Brake System as developed by the Bendix heavy vehicle system group (their drawing number SA-8117-99). With this is an explanatory writeup describing a circuit operation for normal running, parking position and for service brake failure on the rear or front axle.

We would appreciate receiving your comments and possibly your approval for use in compliance with safety standards #121.

As previously mentioned we would like to avoid the use of spring brakes especially on the tag axle because these wheels are independently sprung and have a tendency to lock up because they do not have a load dividing connection with the drive wheels.

I would appreciate your help on these matters and hope to hear from you soon.

With warmest personal regards,

Sincerely yours,

Harry L. Cuthbert -- Chief Engineer, Eagle International Inc.

Enc: 2

SA-9117-99

EXPLANATORY WRITE-UP

NORMAL RUNNING

1. All reservoirs charged and accessory pressure protection valve open.

2. Parking Control Valve handle in release position. DD-3 Valve (Item 20) does not deliver air. DD-3 locks are disengaged. Service Interlock Valve controlled from its delivery line.

3. "Stand-by" Valve (Item 15) does not deliver any brake valve air, and low pressure indicator switches are open.

4. Service brakes can be applied by treadle valve; primary section of the brake valve applies rear axle and secondary section of the brake valve applies front axle.

SECONDARY BRAKES

1. A service brake failure, which would result in a rear axle circuit reservoir pressure loss will cause the "Stand-by" Valve (Item 15) to open. This will supplement the front axle brakes with rear axle brakes by applying modulated from axle circuit service pressure to the parking diaphragm.

2. A front axle circuit service brake failure will only cause a loss of front axle braking. Full service brakes can be applied on the rear axle through the treadle valve (Item 14).

3. In event of a broken treadle, the parking brakes can be applied as a "Back-up" emergency.

PARKING POSITION

1. When Parking Control Valve Handle (Item 18) is moved to the "park" position, the DD3 locks engage. The parking DD3 Valve will first deliver adequate pressure to the DD3 parking diaphragm, and then exhaust it automatically. In this condition, the parking application will remain applied strictly by "a mechanical means."

2. Service Interlock Valve being decontrolled, is closed and parking brakes cannot be released until PP-1 is pushed and a full service application is made and released, in this sequence.

RCF: dw Current for Drawing Revision #7; 6/18/74 (Graphics omitted) ITEM QTY DESCRIPTION 1 1 AIR COMPRESSOR 2 1 GOVERNOR 3 1 RESERVOIR-SUPPLY 4 1 (Illeg.) 5 1 (Illeg.) 6 1 (Illeg.) 7 1 (Illeg.) 8 3 DRAIN COCK 9 1 SAFETY VALVE 10 1 PRESSURE PROTECTION VALVE 11 3 SINGLE CHECK VALVE 12 3 LOW PRESSURE SWITCH 13 2 AIR PRESSURE GAUGE 14 1 (Illeg.) 15 1 (Illeg.)

TWO-STEP RELEASE OF DD-3 ACTUATORS.

2. (Illegible Words)

3. (Illegible Words)

(Graphics omitted)

(Illeg. table)