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8.3.2.1 Application for Certification
8.3.2.1.1
The application required in 8.3.1.2 shall include information on the expected maximum impact speed, maximum and minimum total loads, and complete data for the oil porting in relation to the effective buffer stroke.
8.3.2.1.2
The drawings required in 8.3.1.2.2(b) shall show
(a) the exact construction of the buffer
(b) all dimensions of each part
(c) all pertinent information concerning materials, clearances, and tolerances
(d) the data as marked on the buffer marking plate required by 2.22.4.11
8.3.2.2 Test Sample
Tests shall be made on a buffer of each type or design to be installed. Each buffer shall conform to the documents submitted and have the following oil portings:
(a) the porting having the range of the maximum loads for which the buffer is designed
(b) the porting having the range of the minimum loads for which the buffer is designed
8.3.2.3 Testing Equipment
The testing equipment shall be designed to perform the tests specified herein and to determine that the buffer conforms to all the requirements of Section 2.22 for oil buffers and shall also conform to 8.3.2.3.1 through 8.3.2.3.3.
8.3.2.3.1 Calibration of Test Weight
The required drop-test load shall be accurate to within ±1%.
8.3.2.3.2 Guiding of Test Weight
The test weight shall be guided to ensure that when dropped onto the buffer, its travel shall be substantially vertical.
8.3.2.3.3 Test Instruments
The instruments used to measure the test results shall conform to the following requirements:
(a) The instruments shall be the recording type.
(b) The instruments shall provide data for the plotting of the buffer performance curves showing time intervals, travel of test weight, velocity of test weight, and retardation of test weight during the buffer stroke, and shall be accurate to within the following tolerances:
(1) The timing device shall record time in increments of not more than 1/60 s during the entire buffer stroke.
(2) Time increments and total time shall be recorded with an error of less than ±0.5%.
(3) The position of the test weight at each time interval shall be recorded with an error of less than ±0.1%.
(4) Time, travel, velocity, and retardation shall be determined by means of a device that will provide the accuracy specified.
8.3.2.4 Installation of the Buffer and Preparations for Tests
8.3.2.4.1 Foundation and Location of the Buffer
A buffer of the spring-return type shall be placed on a foundation designed to withstand without appreciable deformation the forces resulting from the buffer compression on the drop tests. The buffer shall be installed in a vertical position and located centrally with relation to the drop-test weight.
8.3.2.4.2 Securing of the Buffer
The buffer shall be secured by bolts in accordance with the manufacturer's drawings or by equivalent means to
(a) the foundation for buffers of the spring-return type
(b) the underside of the center of the test drop-weight for buffers of the gravity-return type
The centerline of the buffer, when secured in place, shall be vertical to within 0.25 mm (0.01 in.) in the stroke of the buffer.
8.3.2.4.3 Special Adjustments
The buffer test shall be on a production model or a buffer identical to the model to be produced. Modifications or special adjustments for the purpose of meeting the test requirements are prohibited.
8.3.2.4.4 Filling the Buffer With Oil
The buffer, after being installed, shall be filled with oil to a level at or between the manufacturer's gauge line or lines. The oil shall conform to 2.22.4.9 and the data specified on the buffer marking plate.
After filling the buffer with oil, the procedure outlined below shall be followed to ensure that a constant oil level has been established.
(a) The buffer shall be fully compressed at slow speed, and shall then be allowed to return to its fully extended position and remain there for at least 10 min. The oil level shall then be checked.
(b) If the oil level as previously determined has changed, due to the elimination of entrapped air or due to the retention of air under pressure within the buffer, the change in level shall be noted and the procedure repeated until a constant oil level is obtained when the buffer is in its extended position.
(c) If the oil level tends to remain above the level to which it was filled, the air vents, if provided, should be checked for obstructions.
(d) When a constant oil level has been established, the level shall be adjusted to the manufacturer's lowest gauge line, and the exact level noted and recorded before making the drop tests hereinafter specified.
8.3.2.5 Buffer Tests
Each oil buffer with oil portings as submitted shall be subjected to tests for retardation, strength, oil leakage, plunger return, and lateral plunger movement, as hereinafter specified.
8.3.2.5.1 Retardation Tests
The following drop tests shall be made for each buffer porting specified in 8.3.2.2, from a height such that the striking velocity of the falling weight will be equal to 115% of the rated car speed for which the buffer is designed:
(a) three drop tests with a total test weight equal to the manufacturer's rated maximum load for which the porting is designed [see 8.3.2.2(a)]
(b) one drop test with a total test weight equal to the manufacturer's rated minimum load for which the porting is designed (see 2.7.2.2)
Following each drop test, the buffer shall be held in its fully compressed position for a period of 5 min, and shall then be allowed to return freely to its fully extended position and stand for 30 min to permit return of the oil to the reservoir and to permit escape of any air entrained in the oil.
On each of these tests, the average retardation of the test weight, during the stroke of the buffer, shall not exceed 9.81 m/s2 (32.2 ft/s2), and any retardation peak having a duration of more than 0.04 s shall not exceed 24.5 m/s2 (80.5 ft/s2).
On completion of the drop tests, no part of the buffer shall show any permanent deformation or injury.
8.3.2.5.2 Strength Tests
(a) Two drop tests shall be made as follows:
(1) One drop test shall be made with the porting as specified in 8.3.2.2(a), with a total test weight equal to 120% of the manufacturer's rated maximum load, from a height such that the maximum velocity attained by the falling weight during the buffer compression shall be equal to 125% of the rated car speed for which the buffer is rated. In this test, the retardation shall be noted and shall be permitted to exceed the values specified in 8.3.2.5.1.
Immediately following this test, the buffer shall be examined externally for visible deformation or injury. If no damage is apparent, the buffer shall then be fully compressed at low speed and then released to determine if it will return freely to its extended position.
(2) After the buffer has been examined externally and has returned freely to its extended position, a second drop test shall be made from the same height and with the same load as specified in 8.3.2.5.1(a). During this test, the retardation shall not exceed the corresponding retardation developed in the test specified in 8.3.2.5.1(a) by more than 5%.
(b) If, for a given stroke of a buffer having more than one porting, the construction of the buffer varies for the different portings, then a strength test similar to that specified in (a)(1) shall also be made for the porting having the range at minimum loads for which the porting is designed as specified in 8.3.2.2(b).
Following each drop test, the buffer shall be held in its fully compressed position for a period of 5 min, and shall then be allowed to freely return to its fully extended position and stand for 30 min to permit return of the oil to the reservoir and to permit the escape of any air entrained in the oil.
8.3.2.5.3 Oil Leakage Tests
Tests for oil leakage shall be made concurrently with the retardation tests specified in 8.3.2.5.1 and the drop test specified in 8.3.2.5.2(a)(2) to determine the loss of oil during these tests. The oil level shall be noted after the buffer has returned to its fully extended position following each drop test, and after the time interval specified in 8.3.2.5.1.
The drop in oil level, as indicated by these measurements, shall show no loss of oil exceeding 5 mm/m (0.06 in./ft) of buffer stroke, but in no case shall the loss be that the oil level is below the bottom of the plunger or the highest metering orifice, whichever is higher.
Where the volume of oil above the porting is small when the buffer is filled to its normal working level, the laboratory shall be permitted to make additional tests for oil leakage.
8.3.2.5.4 Plunger-Return Test
During the drop tests specified in 8.3.2.5.1 and 8.3.2.5.2, the time required for the buffer plunger to return to its fully extended position, measured from the instant the test weight is raised clear of the buffer until the plunger has returned to its fully extended position, shall be noted. This time shall be not more than 90 s.
Should the plunger fail to return to its fully extended position or should the time required for it to return to its fully extended position exceed the time specified, the manufacturer shall either submit a duplicate buffer or install a new pressure cylinder and piston, following which the plunger-return test shall be repeated. Should the buffer again fail to meet the plunger-return test requirements, it shall be rejected.
Buffers of the spring-return type shall be tested for plunger return with a 20 kg (45 lb) test weight resting on top of the plunger during the test. The plunger shall be depressed 50 mm (2 in.), and, when released, the plunger, while supporting the test weight, shall return to its fully extended position within 30 s.
8.3.2.5.5 Tests for Lateral Movement
The following tests shall be made for lateral movement:
(a) Spring-Return-Type Buffers. The lateral movement at the top of the fully extended plunger shall be accurately measured, the upper end of the plunger being manually moved from its extreme right to its extreme left position. One-half of the total movement measured shall be considered as being the true lateral movement at the top of the plunger and shall not exceed 5 mm/m (0.06 in./ft) of buffer stroke.
(b) Gravity-Return-Type Buffers. A similar test for lateral movement shall be made. The measurement shall be taken at the lower end of the buffer cylinder when the buffer plunger is fully extended and braced to prevent lateral movement. One-half of the total movement measured shall not exceed 5 mm/m (0.06 in./ft) of buffer stroke.
8.3.2.6 Certification
8.3.2.6.1
After the buffer has been subjected to all of the specified tests and all test records and data indicate that it conforms to Section 2.22 and to the requirements of 8.3.2, the laboratory shall issue a test report and a certificate to the manufacturer.
8.3.2.6.2
The certificate shall conform to 8.3.1.3.1 and shall include the following:
(a) the maximum impact speed
(b) the maximum total load
(c) the minimum total load
(d) specification of the fluid
(e) a statement to the effect that the buffer having the particular stroke and portings tested has met the requirements of Section 2.22 and 8.3.2 for the maximum and minimum loads as stated in the certificate
8.3.2.6.3
When the test results are not satisfactory with the minimum and maximum total loads appearing in the application, the laboratory shall be permitted to, in agreement with the applicant, establish the acceptable limits.

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8.3.2.6.2 General Requirements,
) the minimum total load (d) specification of the fluid (e) a statement to the effect that the buffer having the particular stroke and portings tested has ...