1、I NCH-POUND I MI L-J-261 49E 30 December 1988 SUPERSEDING MI L-J-261 49D 12 June 1987 (See 6.6) * MILITARY SPECIfICATION GENERAL SPECIFICATION FOR JACK, HYDRAULIC, AIRCRAFT MAINTENANCE, This specification is approved for use by all Departments and Agencies of the Department of Defense. 1 . SCOPE 1.1
2、 Scope. This specification covers the general requirements for weapon systems hydraulic jacks as used with all types of military aircraft. - t I r ! L E f i. 1.2 Classification. All aircraft jacks shall be classified as to their design or use. These classifications shall be.in accordance with Table
3、I. TABLE 1. Classification of Aircraft Jacks. CLASSIFICATION CHARACTERISTIC OF REFERENCE OF JACKS JACK DESIGN LANDING GEAR HAND CARRI ED- MS26566 (AXLE) DOLLY MOUNTED CANTILEVER AIRFRAME FIXED HEIGHT MS33589 (UNIPOD quantity; warning symbol; signal word designating degree of hazard; affirmative stat
4、ement of hazards; precautionary measures covering actions to be followed or avoided; instructions in case of contact or exposure; antidotes and notes to physic.ians; instructions in case of fire, spill, or leak; instructions for handling and storage; and disposal instructions. Characteristics and op
5、erating-hazards which require labeling include: toxic, high toxic, irritant, corrosive, strong sensitizer, combustible liquid, flammable, extremely flammable liquid, dangerously reactive, pressure- generation, explosive, magnetic, ionizing radiation, non-ionizing radiation; high voltage, implosion,-
6、 noise, and etiologic agent. Marking of hazardous materials shall be in conformance .with establ i shed and approved procedures. 3.5.1.3 Recycled, virgin and reclaimed materials. When the intended use of the aircraft jack(s) will be jeopardized by the use of reclaimed or recycled materials these mat
7、erials shall not be used. However, the following shal-1 apply: 6 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-J-261 49E MIL-J-26L49E L7 9 7779706 OL938B7 B 9 a. There is no exclusion to the use of recovered materials. b. There is no requiremen
8、t that an i tem be manufactured from virgin materi al s. c. Within 1 year from the date of issue by the environmental protection agency of guidelines designating items which are or can be produced with recovered materials, specifications for such products require the use of recovered materials to th
9、e maximum extent possible. 3.5.2 Metals. Metals shall be corrosion resistant or treated to resist corrosion due to fuels, salt fog, or atmospheric conditions likely to be encountered in.strage or normal service. Stock used in the fabrication of jacks shall have a properly refined structure with unif
10、orm elemental distribution, sound and free from nonmetallic inclusions, injurious porosity, excess segregation, and soft or hard spots. Castings shall be of uniform quality, free from blowholes, excess porosity, and soft or hard spots. All castings shall be subjected to a seasoning or aging process,
11、 either natural or artificial, to insure maximum stabi 1 i ty. 3.5.2.1 Dissimilar metals. Unless specifically protected against electrolytic corrosion, dissimilar metals shall not be used in intimate contact with each other. Dissimilar metals are defined in and s.hall be used in accordance wi th MIL
12、-STD-889. 3.5.2.2 Standard steel. Suitable steel complying with ASTM or AIS1 standards shall be uti 1 ized in the manufacture of the jack 3.5.2.3 Welding material. All welding of the jack shall be in accordance with the structural welding code for steel, Dl.1-86, as issued by the American Welding So
13、ciety (AWS) and welding aluminum shall be in accordance with 01.2-83. 3.5.2.4 Brazing. All brazing shall be accomplished in accordance with the Brazing Manual 1976 issued by the American Welding Society. 3.6 Design and construction. The jack shall be axle, cantilever, unipod or tripod, designed for
14、the load capacity required. The aircraft configuration which will effect the jack installation and operation shall be considered in the design of all jacks. The jack shall be designed and constructed so that all parts are made for assembly without interference and no parts will work loose in service
15、. The jack shall be designed and constructed to withstand the strains, jars, vibration, and other.conditions incident to shipping, storage, installation and service. MS26566 or MS33589 *shall be used as design guides. 3.6.1 Component arrangement. Al 1 components shall be arranged for maximum ease of
16、 operation and maintenance consistent with the utility and efficiency required to conform to the requirements specified herein. 7 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-J-26347E L7 m 777770b 0373888 T m MIL-J-26149E 3.6.1.1 Component sel
17、ection. All components shal proper clearances and adjustments. They shall so work will supply the rated capacity. 1 be new and shall have together that the jack 3,6.1.2 Component maintenance. All components shall be selected on the basis of maximum life cycle with a minimum of maintenance. Selection
18、 shall be made primarily from approved standard parts using the best engineering practices. Whenever possible extended life parts shall be utilized. As required by the contract the parts control program shall be in accordance with MIL-STD-965. 3.6.2 Reliability. (MTBF) of not less than for a 1-cycle
19、 mission at The jack shall have a-mean-time-between-failures 0.9 confidence (see 6.7.4). 108 cycles with a reliability of not less than 0.9908 3.6.3 Maintainability. The jack shall be designed and constructed as specified herein and to provide the following: a. Minimum number of parts consistent wit
20、h reliability and performance specified herein. b. Minimum amount of training and time necessary for assembly, disassembly, location of trouble sources, and maintenance including servicing. Where practical, parts and components shall be located or positioned for rapid and simple inspection and recog
21、nition of excessivewear or potential failure. c. Permit adjustments, servicing, replacement of parts and components, and other maintenance with minimum disturbance to other equipment parts or components. Parts and components shall be located for ample and rapid access unless performance .or re1 iabi
22、lity will be appreciably degraded by the accessible -location. In performing maintenance, if engineering reasoning or data determines that physical or visual interference between items cannot be avoided, the i tem predicted to require the most maintenance shall be located for best accessi bi 1 i ty
23、and ease of maintenance. d. Permit maintenance with general purpose tools and equipment normally available commercially. Use of special purpose tools and equipment shall be subject to .approval by the procuring activity. e. Minimum number of tools required for maintenance by design practices such as
24、 reducing the variety of bolt head sizes- to the practicable -minimum; 8 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-J-26247E 27 W 7777706 0273887 L W MIL-J-26149E f. Foolproofness - Where improper installation of an item could cause malfunct
25、ion of the item or the equipment in which it is installed, an unsymmetrical mounting means shall be provided where practical. That mounting shall allow the item to be installed only in its proper operating position. If an unsymmetrical mounting means is not practical, the item shall be so mounted th
26、at its proper operating position can be readily and visibly determined by service maintenance personnel. g. Repair kits and soft kits shall be desig-ned and developed to extend the life of the jack assembly by repairing or replacing those piece parts that are subject to wear during normal use. 3.6.4
27、 Capacity and type. The rated capacity shall be specified in U.S. tons ( kg.). The type of jack shall be specified as axle, .cantilever, unipod or tripod (see 1.2 and 6.2). 3.6.5 Floor loading. The jack base or foot pads shall be of such proportions, relative to floor contact area, as to prevent flo
28、or loading in excess of 400 psi (2758 kPa) when supporting a rated capacity load. However, in those circumstances where tight clearances or special aecomodations are necessary, the floor loading may not exceed 600 psi- (4137 kPa). Floor loadings *in excess of 400 PS1 (2758KPA) will require approval
29、of the responsible procuring activity. 3.6.6 Mobility. Jacks having a gross weight in excess of 120 pounds (54.4 kg.) shall be provided with type I, class lb mobility in accordance with MIL-STD-1784 except that the slope requirement shall be a maximum of 15“. 3.6.6.1 Casters or wheels. Unless otherw
30、ise specified by the procuring activity, al 1 casters shall be furni shed in accordance with requirements of MS24380. Casters on tripod or axle jacks may be spring loaded for ease of placement. 3.6.6.2 Towbar. A towbar meeting the requirements for type I, class 2 of MIL-STD-1784 shall be provided. W
31、hen specified, provisionsshall be made to secure the towbar to the jack structure when not in use. 3.6.6.3 Carrying handles. All hand carried jacks shall have carrying handle(s. The design of the carrying handles shall favor the user. Handles shall be ruggedized and located in relationship to the ce
32、nter of gravity (cg) such that the jack is easily controlled while it is being moved about. Also, if possible, the carry,ing handles may be used to protect the controls while the jack is in operation. A jack having a gross weight not to exceed 60 lbs. (27.2 Kg) shall require only one handle. For a j
33、ack weighing between 61 lbs. (27.7 Kg) to 120 lbs. (54.4 Kg), two handles shall be required. Any jack exceeding 120 lbs. shall meet the mobility requirements stated herein. 3.6.7 Heat treatment. Heat treatment of steel materials shall be- in accordance with MIL-H-6875. 9 Provided by IHSNot for Resal
34、eNo reproduction or networking permitted without license from IHS-,-,-MIL-J-261 49E 3.6.8 Structural design. The jack ram and cylinder shall be designed to include a factor of safety of 1.75 based on the rated capacity of the jack. The remainder of the jack supporting structure .shall be designed fo
35、r a factor of safety of 2.0 based on the rated capacity of the jack (see 6.7.8). 3.7 Performance. The jack shall operate under the following conditions: . An internal pressure equal to 1-112 times the pressure at rated capacity without leakage. b. Maximum settling of 0.020 inch (0.51 mm) per ram per
36、 hour under rated capacity load. c, . Rai sing verti cal ly 150 percent of the rated capacity load. d. Withstanding a horizontal load equa1,to 15 percent of rated capacity while supporting a rated capacity loadwi th the ram fully extended and the screw extension retracted. e. Operating at all temper
37、atures ranging from -65F to t130“F (-53.9“C to 54.4“C). f. Two hundred cycles of raising a rated capacity load and sixty cycles of rai sing a rated capacity load- while being fubjected to a horizontal load of 15 percent of rated capacity. g. Dust particles as encountered in desert areas. h. Exposure
38、 to salt fog or salt laden atmosphere. j. Operating in rain, snow, or bright sunlight. l. Interface properly and securely with the aircraft jack points. m. The hydraulic fluid system shall have overload protection capabi 1 i ti es. 3.8 Hydraulic system. The hydraulic system (figure 1) shall be desig
39、ned for operation with hydraulic fluid conforming to MIL-H-5606, MIL-H-83282, or MIL-H-81019 and shall consist of a jack ram and cylinder, pump, necessary bypass and check valves, reservoir, tubing, hose and fittings. The hydraulic system sha-11 be provided with a device designed and located to blee
40、d all entrapped air from the system. The jack shall be equipped with a self- contained, hand operated, hydraulic pumping system and shall also have provisions for connection to an external hydraulic pumping source when specified. Hydraulic hose shall conform to MS28759 and the hose shall have a fema
41、le connector 43A13905 which will mate with the connector on the jack. The external leakage of the system shall not exceed 0.05 cc per hour at any pressure. For design purposes the optimum hydraulic pressure shall be 3000 psi *(20,684 kPa) at the rated capacity. 10 Provided by IHSNot for ResaleNo rep
42、roduction or networking permitted without license from IHS-,-,-i MIL-J-26149E ; PUMP. ASSEMBLY .SPRING LOADED CHECK VALVE PUMP (ONE OR MORE) SAFETY BY-PASS PUMP ASSEMBLY CHECK VALV RE LEAS E VALVE SUCTION I 1 HYDRAULIC FLU ID RESERVO1 R i 1: I , long and shall be provided with a suitable grasp (knur
43、led) surface. For jacks of less than 10 tons (9070KG) capacity a shorter handle may be provided ie 18“ (0.456M) or 20“ (0.51M). Provisions *shall be made to stow the pump handle on-the jack. The pump inlet shall be provided with a screen-of approximately 50-mesh, 0.007-inch (0.18 mm) diameter brass
44、wire. The internal leakage of the pump shall not exceed 5.0 cc per hour. * 3.8.2 Safety Bypa?s valve. The jack shall .be equipped with a bypass valve adjusted and set to 105 to 110 percent of the rated capacity of the jack. This valve shall be-located between the pump check valve and the jack ram to
45、 prevent overload and shall vent into the reservoir. 3.8.3 Safety device. The tripod jack ram(s shall be provided with a hydraulic pressure removed. The safety device shall prevent dropping the load during and after the jacking operation in the event,the hydraulic system fai 1s. The safety devi ce s
46、hall be in operation at al 1 times when the jack ram is raised and supporting the load. . mechanical safety device capable of supporting the rated load with the 3.8.4 Reservoir. The hydraulic fluid reservoir shall have a capacity sufficient to fully extend the jack ram plus a 10-percent minimum rese
47、rve. air relief valve and filler plug in accordance- with Drawing 1128AS121 shal provided on top of the reservoir (not shown in Figure 1). _. An 1 be * 3.8.4.1 Reservoir Dumping or safety valve. The dumping or safety valve (not shown in Figure No. 1) shall be located on or near the top of the reserv
48、oir. This valve shall automatically vent excess air from the reservoir when this air is being replaced by hydraulic fluid. This valve shall be sized to accomodate the maximum flow of hydraulic fluid that may pass through the release valve. Also when relatively small-sized jacks are tipped or overtur
49、ned this valve may not leak hydraulic fluid. * 3.8.4,2 Reservoir overflow vent valve. Those hydraulic jack systems that include a connection for an external pumping source connector shall also include an overflow vent valve located at the top of the reservoir (not shown in Figur.e No. 11 This vent shall relieve excess fluid that may be inadvertently transferred from the external pumping source. The vent valve shall open at about 100 psig pressure to prevent any damage to the
