1、MIL-STD-2151 20 999991L 0033031 5 I c-54 -40 MIL-STD-P151(SH) 25 July 1984 . MILITARY STANDARD INCLINED LADDER TREAD TEST METHODS AND EQUIPMEW FOR WEAR, SLIP-RESISTANCE AND IMPACT ,- THIS DOCUMENT CONTAINS Ja PAGES Licensed by Information Handling ServicesMIL-STD-2151 20 W 77734LL 0033032 7 MIL-STD-
2、2151(SH) 25 July 1984 DEPARTMENT OF THE NAVY NAVAL SEA SYSTEMS COMMAND Washington, DC 20362 Inclined Ladder Tread Test Methods and Equipment for Wear, Slip-Resistance and Impact. MIL=STD-2151(SH) 1. This Military Standard is approved for use by the Naval Sea Systems Command, Department of the Navy,
3、and is available for use by all Departments and Agencies of the Department of Defense. 2. Beneficial comments (recommendations, additions, deletions) and any perti- nent data which may be of use in improving this document should be addressed to: Commander, Naval Sea Systems Command, SEA 5523, Depart
4、ment of the Navy, Washington, DC 20362 by using the self-addressed Standardization Document Improvement Proposal (DD Form 1426) appearing at the end of this document or by letter. ii Licensed by Information Handling Servicesb - MIL-STD-2353 20 = 7779733 0033033 7 W MIL-STD-2 15 1 ( SH) 25 July 1984
5、I 3. Tests have been incorporated in this standard which more closely simu- I late shipboard conditions and permit an evaluation of sample ladder treads with I some degree of assurance that shipboard performance will be predicted. FOREWORD 1. Historically, ladder treads for shipboard use have not be
6、en tested except for the type G tread in accordance with Drawing 804-0860041, which is fabricated of layered glass fiber reinforced plastic. The acquisition specifica- tion for the type G tread required the following tests for wear, slip-resistance and impact: (a) The specified test for wear employe
7、d a rotating steel disk to which loose abrasive was applied. the tread surface was forced against the disk causing wear on the sample. The thickness change was then measured and related to the number of turns of the disk. simultaneously by measuring the force required to pull a weight with three rub
8、ber feet across the samples for dry, wet and oily conditions. The force was then converted to coefficient of friction. repeatedly dropping a 2-pound steel ball onto a 6- by 6-inch tread sample in a closely spaced pattern. The sample was then inspected for damage or loss of adhesion. Since most damag
9、e due to impact occurs on the nose of treads, the impact test A 2- by 3-inch sample of (b) To measure slip-resistance, three worn samples were tested (c) The impact test specified for the type G tread consisted of did not simulate actual conditions. 2. It has been determined that tests for wear and
10、slip-resistance were unsatisfactory for the following reasons: (a) The sample was honed to a flat, smooth surface, unlike actual shipboard wear caused by the scuffing action of shoe soles imbedded with abrasive dirt particles. the same for lab tests as for shipboard tests. to the influence of the no
11、se configuration on tread life and slip-resistance. The method of measuring wear indicated average wear rate of the points measured and did not allow prediction of the tread life. Slip-resistance was measured for the honed lat samples and did not reflect the slip-resistance of a worn tread nose. (b)
12、 The relative wear rates of different types of treads were not (e) The test was conducted on a flat sample of tread without regard (d) (e) iii Licensed by Information Handling ServicesMIL-STD-ZLSL 20 W 77797LL 0033039 O W MIL-STD-2151( SH) 25 July 1984 CONTENTS 2 2 2 2 2 2 3 3 3 3 3 4 4 4 4 4 4 4 5
13、5 5 5 6 . iV Licensed by Information Handling Services MIL-STD-2353 20 = 7799733 0033035 2 W Figure 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. MIL-STD-2151(SH) 25 July 1984 CONTENTS - Continued FIGURES UWLG yuu Tread impact test fixture -_I_ Tread positioning Clamp positioning Rigging for slip-resistance te
14、st . Example of completed record form . Example of tread test record . Inclined ladder treads test results summary - Testing for pad pressure . Tread impact test record . Page 7 8 9 10 10 11 12 13 14 15 17 v/vi Licensed by Information Handling ServicesMIL-STD-2151 20 77779LL 0033036 4 W MIL-STD-2151
15、(SH) 25 July 1984 1. SCOPE 1.1 Purpose. This standard describes test methods and equipment for testing compound filled ladder treads intended for use on Navy ships for wear, slip-resistance and impact resistance. 2. REFERENCED DOCUMENTS 2.1 Issues of documents. The following documents of the issue i
16、n effect on date of invitation for bids or request for proposal, form a part of this standard to the extent specified herein. DRAWINGS NAVAL SEA SYSTEMS COMMAND NAVSHIPS 804-0860041 - Ladder Inclined Tread Details, Aluminum, Steel. NAVSEA 804-5959201 - Test Machine For Ladder Treads. (Copies of draw
17、ings required by contractors in connection with specific acquisition functions should be obtained from the conrracting activity or as directed by the contracting officer.) 3. DEFINITIONS Not applicable. 4. GENERAL REQUIREMENTS 4.1 General description. Shipboard tests and examinations have shown that
18、 maximum tread wear and damage occur on the nose of the tread. Test methods for wear, slip-resistance and impact, as described herein, provide an approximate simulation of deterioration of inclined ladder treads encountered on board U.S. Navy ships. 4.1.1 Wear test method. The wear test is designed
19、to provide a wear pattern of approximately the same contour and angle as for shipboard performance by drawing spring-loaded abrasive pads across the nose at an average angle of 30 degrees. The 3- by 6-inch pads are attached to a pair of articulated paddles carried by a rotating arm. The arm is rotat
20、ed by a 1/3-horsepower (hp), 28.5 revolutions per minute (r/min) gear motor, causing 57 pad strokes per minute. The number of strokes are counted, permitting preset stroke count intervals as specified in the applicable acquisition document for measuring wear. Wear is measured at 17 positions in the
21、contact area with a dial micrometer through holes in a jig plate. Wear rate is compared with the thickness of the slip- resistant material to indicate the life of tread wear. 1 Licensed by Information Handling ServicesMIL-STD-2151 20 W 7777711 0033037 b W MIL-STD-2151(SH) 25 July 1984 4.1.2 Slip-res
22、istance test method. The slip-resistance is measured at intervals as specified in the applicable acquisition document by applying a dry, wet, and an oily rubber shoe sole pad to the wear pad and measuring the force required to pull the pad across the nose. 4.1.3 Impact resistance test method. Impact
23、 resistance is tested by dropping a Z-pound steel ball on various points of the tread flat and nose and then examined for cracking or loss of slip-resistant material. 5. DETAILED REQUIREMENTS 5.1 Test equipment and accessories. 5.11 Description of wear test machine. The wear test machine, as shown o
24、n Drawing 804-5959201, consists of a motor driven twin leg stroke assembly. Each leg consists of an articulated, spring loaded, wear pad support. The 3- by 6-inch rubberized abrasive wear pad is mounted to the pad support with two-sided foam tape. A tread support fixture is provided to permit mounti
25、ng of the tread at the required angle, height and transverse position regardless of the tread design. A predetermining mechanical counter is mounted to record each revolution (two strokes per revolution) and to stop operation when the desired number of strokes is reached. 5.1.2 Wear measuring access
26、ories. The wear measuring accessories consist of a data point locating jig as shown on figure 1, and a depth dial micrometer, Starrett No. 644, or equal. The jig is designed to permit the perpendicular measurement of tread thickness changes at an angle of 30 degrees to the top of the tread at 17 poi
27、nts on the nose wear area. One end support for the jig is adjustable to eliminate rocking due to unevenness of the tread surface. additional holes in the jig are provided to permit reference readings to verify consistent jig positioning. Two 5.1.3 Slip-resistance measuring accessories. Slip-resistan
28、ce is meastired by pulling sole pads across the wear contact area and measuring the force required. Three sole pads (see figure 2) are used. Sole material is “Cats Paw“, or equal, 12 iron (1/4 inch thick) rubber shoe sole material. Plain tap water is used for the wetting agent for the wet test condi
29、tion, and SAE 1OW-30 motor oil is applied for the oily condition. Model DPP 50, or equal, with a scale of zero to 50 pounds and 0.5 pound gradua- tions, The winch is a l/l35-hp by 12-r/min gear motor mounted as shown on Drawing 884-5959201 and fitted with a 5/8-inch diameter shaft extension to provi
30、de a tow speed of approximately 24 inches per minute. 1/8-inch diameter cotton rope loop and a small diameter flexible tow wire fitted with a hook for attachment to the force gage. The force gage is a Chatillon Tow rigging is one . 5.1.4 Impact equipment. Impact resistance is measured using the test
31、 fixture shown on figure 3. from the helght and at the locations specified. for variations in drop height, tread length and impact angle. used for accurate position of the impact point and a hand-held vacuum release device (Neward Enterprises, Inc., Mitivac !I6810 or equal) is used for dropping A 2-
32、pound steel ball is dropped onto the tread A plumb bob The fixture can be adjusted Licensed by Information Handling Services/ MIL-STD-2351 20 M 7797933 0033038 8 MIL-CTD-2 15 1 ( SH) 25 July 1984 the ball. Full treads may be bolted directly to the fixture. When cap treads are tested, a type F extrud
33、ed aluminum tread (see Drawing 804-0860041) is first installed, and the cap tread is bolted or clamped to it. Foam padding is installed in the bottom of the fixture to catch the ball after impact. 5.2 Test methods. 5.2.1 Wear test procedure. 5.2.1.1 Tread mounting. The sample tread shall be mounted
34、as shown on figure 6 using C-clamps. The mounting fixture shall be adjusted so that the tread is in the location and angle as shown on figure 4. shims may be required when the tread is too narrow or has ribs which prevent solid clamping to the fixture. Transverse positioning is not critical. The cla
35、mps shall be located to also secure the positioning blocks for the wear measuring jig as shown on figure 5. Wood blocking or 5.2.1.2 Wear pad installation. The 3- by 6- by 3/8-inch rubberized abrasive wear pads, shall be affixed to the face of the pad support with three strips of 1- by 1/16-inch, tw
36、o-sided urethane foam tape along the length. Contact surfaces of the pad shall be thoroughly cleaned with soap and water and dried. Dirt and adhesive residue shall be removed from the pad support with solvent and a razor blade to assure proper adhesion. When the pads show signs of uneven wear or dee
37、p grooves, they shall be smoothed with a dressing stick (Brightboy #90 or equal), or replaced with a new pad. If the pad is worn to less than 3/16-inch thick in any part, it shall be replaced before the next tread test. 5.2.1.3 Machine operation and care. After connecting to a 115 volt outlet, the p
38、redetermining counter shall be set to half the number of strokes as specified in the applicable acquisition document. Pad force on the tread nose shall be checked to ensure proper spring tension by measuring the perpen- dicular force required to pull the pad away from the tread nose. and rope sling
39、may be used for this purpose (see figure 7). If a force of 15 to 18 pounds is not obtained, adjustment of the spring length by modifying the mounting hooks, or replacement of the springs, may be necessary. After any spring has been in service in excess of 50,000 strokes and the pad force falls below
40、 15 pounds the spring shall be replaced. Low force is an indication that the spring may fail from fatigue causing personnel injury and machine damage. The force gage 5.2.1.3.1 Before the wear test procedure, all set screws, mounting bolts and clamps shall be tight, and arm return bumpers and flexibl
41、e coupling inserts shall be in good condition. Lubrication of the gear motor is not required. When necessary, a drop of oil shall be placed on the pad arm pivot for smooth operation and the pivot shaft nuts shall be tightened to reduce play. 5.2.1.3.2 When the thumb lever on the side of the counter
42、is depressed all the way down and released the machine will start and the counter will reset to the present number. Caution shall be taken to stand clear while the machine is in operation. If necessary, the machine may be turned off during operation using the switch with the red cover plate. When us
43、ing the counter lever, stopping and restarting will reset the counter and disrupt the stroke count. 3 Licensed by Information Handling ServicesMIL-STD-215L 20 9999911 0033039 T W I 5.2.3 Slip-resistance measurement. I MIL-STD-2151( SH) 25 July 1984 5.2.2 Wear measurement. 5.2.2.1 Measuring jig adjus
44、tment. Before mounting the measuring jig on the tread, excessive tread surface variations shall be removed in the area of jig contact at each end of the jig with a course file. The jig shall be placed between the clamp blocks as described in 5.2.1.1 and as shown on figure 5. The end plate adjustment
45、 screw shall be loosened at one end and the end plate moved until both end plates sit hard on the tread surface with no rocking. The screw shall be retightened. 5.2.2.2 Depth readings. Tread wear shall be determined by measuring the change in distance from the jig face to the tread surface by placin
46、g the depth dial micrometer through each of the holes in the jig and recording the reading as specified in 5.2.2.3. Data points “R“ (see figure 1) shall be read first and shall be the same for each reading to verify consistent positioning of the jig. Contact surfaces between the jig and micrometer s
47、hall be clean to ensure accurate readings . 5.2.2.3 Reading data. Depth readings, rounded off to the nearest thou- sandth of an inch, shall be recorded (figure 11 illustrates an acceptable format). Daca and initials of the person taking the data shall be recorded. Observations o unusual happenings o
48、r conditions shall also be recorded on the form. 5.2.2.4 Computing the average wear. Initially, and after each specified stroke count interval, depth readings shall be taken of the test sample through the 17 holes in the jig, as shown on figure 1, with the depth dial micrometer. The depth readings s
49、hall be recorded in the left portion of the spaces, as shown on figure 8, corresponding to the hole location in the jig, as shown on figure 1. After the data has been recorded for the final stroke interval, the last readings shall be compared with corresponding initial readings and the differences recorded in the right portion of the appropriate spaces as shown on figures 8 and 10, The highest five differences (10, 13, 14, 12 and 13, spaces with shaded upper right corner) recorded shall be averaged. The average wear figura (12.4 at 50,000 strokes) shall
