1、MIL-P-7873 23 m 7779706 OL8899L 7 m MILITARY SPECIFICATION 3 PASSENGER AND CARGO VEHICIZS; -. GENERAL SPECIFICATION FOR MAINTAINABILITY FEATURES OF 1. SCOPE I 1.1 This epecification covers maintainability features that are to be incorporated in passenger and cargo vehicles, such vehicles include, bu
2、t are not- necessarily limited to, passenger buses and ambulances used for the movement and transport of personnelt and trucks, truck tr8ctors. cargo carriers, trailers, semi-trailers, aud trailer converter dollies used for the movement and transport of cargo and materiel. 1 1 2. A$PLICABLE DOCUMENT
3、S 2.1 There are no documents applicable to this specification. I 3. REQUIREMENTS I 3.1 $MRPLAMI. I 1i I ENGINE (GASOLINE a ,DIESEL) . - _. - .- I .i t i 3.1.1./1 The general requirements or the engine are given i.n 3.1.1 5 1.1 The configuration of the equipment shall permit removal and 3.1.1 . 1.1 O
4、hrough 3 1.1 . 1.5. replacementf of the engine within a minimum length of time, without the re- quirement or removal of an excessive number of components, 1 3.1.1(1.2 The number of disconnect points shall be held to a rnhninum, . 3.1.1;.3 The connectors for wiring, fuel, hydraulic, lubricant, and .
5、and the ditconnecf points shall be easily accessible. alr liner ehall be of standard commercial or AN type. connectorelof the same configuration are mounted near each other, tach con- nector and the associated fitting shall be appropriate. fdenttfied. 1 When two or more 3,1,1.1.4 System components,
6、assemblies, or subassemblies of the engine, such as fuel system, ignition system, elect-icat system, control units, heat exchangers, filters, etc; shall be temovablr! cr Lt ,Laceable, with atnimum requirement for the removal or other componerito, assemblies, or. subassemblies . I 9 1 I ! Provided by
7、 IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-I I I 3.1.1.1.5 The engine and aesociated heavy or bulky components or as- ecmblies shall-be provided with runs for Attachment of lifting eyes or other approved devices to permit safe handling. 3 . 1 . 1.2 3.1.1.2
8、.1 and replacement, using etandard tools, without requirement for removal of other engine parts. It shall be provided with a drain for the removal of fuel or foreign matter. is comnonlp avai lable . FUEL SYSTEM (GASOLINE ENGINE) The fuel filter shall be easily accessible for removal The fuel filter
9、element she.11 be of a type that 3.1.1.2.2 The fuel pump and booster unit shall be eccessible for easy removal and replacement, usng standard tools, without requirement for removal of other engine components. 3.1.1.2.3 The air cleaner shall be accessible for servicing, removal, and replacement, with
10、out requirement for removal of other components. 3.1.1.2.4 The carburetor shall be acceseible for adjustment, removal, and replacement, using common tools. be adjustable tu compensate for wear. The throttle-control linkage shall 3.1.1.2.5 The intake manifold shall be provided with tap(s) for test I
11、purpcsas: 3.1.1.2.6 If the engine is equipped with a fuel prmfng system, the components of this system which require maintenance shall be accessible. 3.1.1.2.7 If the engine is e2 Fuel filters of the duplex-type are preferred. The filter for removal and replacement, using standard tools, I I element
12、s (cartridges) shall be accessible for inspection and replacement, using common.tools, without requirement for removi.1 of engine components or connectink fuel lines. f 3.1.1.3:3 Fuel strainer(8) sh:ll be ahcessible for n8pec:eion and service, using common tools , without requirement for removal of
13、engine components ok connecting fuel lines. - - i- 3.1.1.34 The fuel strainer and fflter caees shall be provided wfth accessible vglves (or pet cocks) to bleed the fuel system of nir. Also, the cases sh 11 be provided with accessible rain valve8 (orpet cocks) for the drainingof I water and foreign m
14、atter. Preference should be given to drain devic$which does not require the use of tools for opegfng or C108fng. I _- 1 3.1.1.3,.5 I The fuel distributor pump (multi- or individual pump) rhall be easily accessible for adjustment, removal, and replacement. 3,1.1.3/,6 The air cleaner shall be accessib
15、le for rervicing, removal, 3.1,1.3.7 All engines employing a scavenging rir pump, rotrry or cen- and replacement. tri fugal blotter, or supercharger or turbocharger shall be provided with accessfble tap(s) in the air header or manifold for attachment of test equipment, i 3.1.1.3.8 A hand or electric
16、 fuel-primng pump shall bo an integral part of the fuel system. the fuel system, and shall provide a method to bleed free) the system of air after fuel system maintenance has been accomplished. If the fuel systim includes a fuel of1 pressure gage, the gage shall be properly protected against pulsing
17、, ta prevent early failure of the gage, The priming pump shell permit initial primfng of 3.1.1.3.9 8 3. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-3.1rl.3.10 Tha governor, fuel line end fuel-line routing, tanks, and .fuel-gage sending unit shall
18、 meet the requirements given in 3.1.1.2.1. through 3.1i1.2.11. 3 o 1 o 1.4 IGNITION SYSTEM (GASOLINE ENGINE) o 3.1.1.4.1 The spark plugs shall be easily accessible for removal and replacement, using standard tools, without requirement for removal of engine componente other than weatherproofing and r
19、adio-interference sup- pression component, when installed. acceisible for easy removal and replacement, without requirement for special tool8 . 3.1.1,4.2 The distributor and coil, or magneto assembly, shall be 3.1.1.4.3 The distributor or magneto lubrication points (grease cup or oil reservoir) shal
20、l be accessible. 3.1.1.4.4 The timing marks shall be clearly visible from the area in The timing shall whicn the timing adjustments will normally be performed. be adjuBtable, using common tools. 3.1-1.5. COOLING SYSTEM. 3.1.1.5.1 The coolant hoses shall be installed so as not to be chafed by other e
21、ngine or vehicle parts. Preference should be given to the use of spring-type hose clamps which maintain a constant peripheral pressure and eliminate the need for clamp adjustment. 3.1.1.5.2 Accessible pet cocks or valves to permit draining the sys- i tem shall bo provided in t;he radiator engine blo
22、ck, and in the water pump i if necessary. #, i 3.1.1.5.3 The radiaior configuration shall permit easy removal and replacement of the radiator. ment using comnon tools. 3.1.1.5.4 The water pump shall be accessible, and capable of adjust- 3.1.1.5.5 Adjustment, removal, and replacement of the fan belt
23、shall 3.1.1.5.6 if the fan is equipped with a shroud, the shroud shall not interfere with adjustment or inspection of other components or assemblies. Where the shroud must be partially or completely iemoved for the performance of matntenance operations, the method af fastenin6 shall pernit removal .
24、be easily accomplished, using coiamon tools. e ,I . Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-v I _Y- and replacem2 The crankcase breather shall be conveniently located bo facilitate cleaning and servicing. using standard tooa, and the location
25、 shall permit drainage directly into waste 3.1.1.6.3 *I The crankcase drain plug shall be accessible f-7 removal, container without the use of adapters or piping, I 3.1.1.6i.4 The oil filter(s) shall be of standard comercial typo, The oil filter shall be accessible fer easy removal and replacement o
26、f . filter element, without requirementvfor removal of engine components other than connecting oil lines. , 3.1.1.6.5 All parts or components requiring lubrication shall be provided with standard grease fittings. If necessary, extended fittings shall be provided to lubricate parts or assemblies whic
27、h are not readily acceseible for direct lubrication, or which are likely to be overlooked because of inaccessibility. - 3,1,1.6.6 The drain, inspection, and fill plugs shall be easfly . accessible, and shall be easily removed and replaced, using common taoi8. 3.1,1.7 EXHAUST SYSTEM. 3.1.1.7.1 - All
28、components of the exhaust system shallbe routed so se not to create a hazard to personnel, and shall be mounted to facilitate easy rempval and replacement,. , e 3.1.1.7.2 All ,hardware used in the exhaust system shall be of standard size. type, to facilitate removal and replacement by one individual
29、, Nuts used with cap screw8 and bolts should be of the semi-capbive 3.1.1.7.3 The spark arrestor, when installed, shall ka accessible for easy removal, cleaning, and replacement. i 3.1.1.7.4 The exhaust gas flow shull be directed away from the vehicle or equipment. Hot exhaust gases shall not come i
30、n contact with any part, O. - Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-P-7873 23 7777706 OL88746 b . . i ! component, or frame member of the equipment where damage to painti or eronion would result. . Where exhaust gases discharge from a v
31、ertical pipi or -silencer, a weather cap or other suitable meann shall be provided to pre- vent witer from entering the exhaust systtm. 1 I I I 3 .2 EIECTRICAL SYSTEM. I I 3 e2 . 1 BATTERIES i 3.2.1.1 The battery location shall permit crsy rccens for testing, 3.2.1.! Ample ventiletion shall be provi
32、ded for normal-use and battery- repleni shmejt of electrolyte, and removal and replacement of- battery . charging periods. I 3.2.2 GENERATOR. 3.2.2.1 The generator output nhall be indicated by an ammeter on the instrument panel . 3.2.2.2. The generator mounting, Idler, or othcr associated belt-drive
33、n engine accessory shall permit adjustment of V-belt tension, using common tools, without necessity for removal of other components. 3.2 . ALTERNATOR . 3.2.3.1 The rectifier shall be mounted in a locatlon where adequate ventilation and cooling air will be provided. 3.2.3.2 Tha rectified output from
34、the alternator shall be indicated . ._ - by an ammeter on the instrument panel. 3.2.3.3 The alternator mounting, idler, or other associated belt- driven accessory shall permit adjustment of V-belt tension, using comon tools, without necessity for removal of ather components. or in tha a-c alternator
35、 and rectifier system shall be accessible for . removal and replacement, and for rervtcing while installed on vehicle. 3.2.4 REGUXATOR.-The regulator employed in the d-c generator system 3.2.5 STARTING MUToRr I I 3.2.5.1 The cabler from the battery to the solenoid or awitch of the t . 1 ,a - 108s+u,
36、 and ahall be adequately insulated and nupported to prevent chafing f 1 rtarting motor shall be of Adequate size to prevent excessive electrical i and po86iblr rhorting . ,I I:. . ,.: ,; ! 5 s. ,. . . .-a . .$ .+ -L- Provided by IHSNot for ResaleNo reproduction or networking permitted without licens
37、e from IHS-,-,- .- 3.2.5.2 The itarting motor shall be energized by means of an electric solenoid Which, if possible, shall be suitably interlocked with the ignitlon system or charging generator, in preference to being energized by remote mechanical cable, bell crank, and lever systems. Where mechan
38、ical means are provided for engagement of the starting motor with the flywheel, the electrical circuit shall be completed after gear engagement. The starting motor shall include provision for automatic disengegement, in the event the operator fails to release the system immediately after the engine
39、starta. 3 .2 . 6 WIRING 3.2.6.1 The wiring rihall be grouped, where practical, in cable or harness form, and should be routed to afford maximum protection from roa8 splash, abrasion, grease, oil, fuel, and excessive heat. 3.2.6.2 All electrical devices, laky468 alarms, terminal strips, etc, that req
40、uire periodic aervice shall be easily accessible. 3.2.7 HORN AND SIREN. 3.2.7.1 The horn or siren,or both, shall be securely mounted in a location which permits maximum audfbility in the direction of travel. It. shall be easfly accessible for adjutment, and ehall be easily teraoved and replaced, usi
41、ng common tools. 3.2.7.2 The horn ehall be operated by a switch button in the center of the steering wheel for a convcntfonal steering system, or in a location which is natural and convenient to the operator. equipped with an afr horn, an electrlc-solenoid air valve shall be employed in conjunction
42、with the horn switch. Where the vehicle is I 3.2.7.3 The airen (if used) shall be controlled by a convonbntly locatea fooe-operated ewitch, or a transfer switch shall be installed to change the airen control to the horn control circuit, or both manr of con- trol shall $e used, 3.2.8 !.LIGHTS. 1: 3.2
43、,8.i All external .lamps of the vehicle ahall be prdrected from possible daTage by means of adequate guarda or similar devices, and shall be easily a cessible. c 3.2.8.3 Head lampa or spot lamps chal1 be mountrd so ar to permit adjustment, using common tools. I Provided by IHSNot for ResaleNo reprod
44、uction or networking permitted without license from IHS-,-,-.- 3.3.1 All fnstruments for operation of the vehicle shall be mounted 3.3.2 The minimum complement Of instruments required for gasoline or (a) HoUr, or running-time, meter (b) Oil pressure gage (c) Water (coolant) temperature gage (d) hete
45、r (e) Fuel quantity gage .- in direct view of the operator. _- - y /- /- diesel engtnes shall be as follove: . 3.3.3 A tachometer shall be installed where control of engine rpm is I . .ian important factor in the proper operation and maintenancq of the equipment, 1 to indicate speed and distance tra
46、velled by the vehich. I f 3.3.4 A speedometer and odometer shalt be installed, where necessary, 3.3.5 Where required for the proper operation of the .vehicle or mounted . . equipment4, or where necessary as an aid to maintenance and trouble rhooting, one or more of the following instruments shall be
47、 incorporated: i (a) Oil temperature gage (engine) .(b) Transmission temperature gage . (c) Transmission pressure gage (d) Manifold vacuum gage (gasoline engine) (e) Fuel pressure gage (diesel gngine) (f) Air-reservoir pressure gage or vacuum-reservoir gage (8) Air-brake chamber or application press
48、ure gage (h) Hydraulic oil-pressure gage (steering eystem) I 3.4 CHASSIS CrnONEKTS. .; . 3.4.1 BRAKE SYSTEMS. , t. 3.4.1e1 HYDRAULIC. f I i 3.4.1.1.1 The mater cylinder shall be eastly accessible for in- , . rpecton, rcplcnishnent of fluid, and adjustment? ucing coon tools 3.4.1.1.2 The wheel-cylind
49、er bleeder vent qhall be of rtandard size, : to permft aaximum utilization of bleeder tank during system maintenance. I .i -3; . f Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,- MIL-P-7873 23 977990b 0388947 L I - _.- /.2- .i I . 9 ! .- . ,-_ . . 3.4.1.i.3 The brake-ahoerdjuatment shall be eaaly .ccesa.ible, and 3.
