52:
136:
161:
87:
20:
109:
shaft, so as to distribute their loads. The engine-critical systems, including the starter drive, are arranged on the high-pressure shaft, with aircraft systems on the low-pressure shaft. The high-pressure shaft also rotates faster than the low-pressure shaft, which may influence the distribution of accessories.
108:
For two-shaft designs, an accessory drive will be taken from the high-pressure shaft, i.e. the outer and shorter of the two concentric shafts. This shaft comes up to speed more quickly when the engine is started. The drive and accessory gearboxes may also be split in two, one driven from each engine
42:
engine. Although not part of the engine's core, it drives the accessories – such as generators, pumps for fuel and lubrication oil, air compressors, hydraulic pumps and engine starters – that are otherwise essential for the operation of the engine or the aircraft on which it is mounted. Accessory
226:, or as a supply of cooling air to other components (to avoid excess heat, this is taken for a low-pressure tapping, or from the LP compressor of a two-shaft engine). One important use for bleed air is for cross-starting of other engines in a multi-engine aircraft.
147:
To make the best use of the limited space for the driveshaft and internal gearbox, the driveshaft runs at high speed, thus allowing it to be of small diameter. This reduces the disruption to the airflow and the size of the hollow fairing that encloses it.
151:
If it is not possible to arrange a single straight path for the driveshaft, it may be arranged in two sections and linked by an intermediate gearbox. This is most commonly required for high-bypass turbofans with large diameter fans.
171:
The packaging of an engine within its nacelle is a complicated task. The accessory drive is usually arranged as a curved casing, so that the various accessories are mounted close to the engine. The casing is a pair of
289:
Additional facilities are provided for a centrifugal oil breather, to separate the drive lubricating oil from the overboard breather air vent. Also access for hand-turning the engine, during ground maintenance.
222:
is also tapped to provide power for accessories, as well as a mechanical shaft drive. Bleed air is particularly useful when a source of compressed air is specifically needed, either to pressurise
191:
are sometimes used for the high-torque drives, typically the starter, as these give smoother running. However helical gears also generate an end-thrust, which then requires a more complicated
97:
The design of the internal gearbox is complicated by the heat and small space available in which to connect the driveshaft. It is usually placed between the compressor outlet and the
546:
123:
Stub shaft drive, where a tubular stub shaft is fitted over the main shaft and driven from it by splines. This stub shaft carries the bevel gear that drives the radial shaft.
539:
183:. Accessories are arranged on both sides of the driveshaft entry, in reducing order of their speed. The gears are usually plain spur gears, running in
126:
Idler shaft drive, a narrow shaft runs parallel to the main shaft. It is driven by spur gears and in turn drives the bevel gear to the main gearbox.
532:
396:
62:
Power for the accessory drive is taken from the central shaft linking the turbine and compressor sections of the engine. This requires an
223:
58:, with the accessory drive mounted beneath. The accessories are removed and their mounting flanges covered by bright red blanking plugs.
930:
920:
329:
198:
The complexity of an accessory drive and its gears is so great that they were used as a theme by the anthropomorphic illustrator
893:
925:
273:
Low-pressure air compressor (cabin air conditioning), where this is not provided by tapping engine compressor bleed air.
497:
793:
667:
517:
1061:
842:
1030:
1056:
878:
55:
873:
644:
51:
299:
950:
868:
728:
112:
To allow for thermal expansion, the drive from the main shaft may be taken by one of three means:
822:
604:
442:
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768:
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682:
599:
404:
1035:
803:
773:
753:
1020:
983:
935:
692:
258:
252:
187:. Idler gears are commonly used between them, to increase the spacing between accessories.
8:
285:
Auxiliary gearbox drive, to a further gearbox that may be required in some installations.
165:
139:
91:
524:
143:
Separate accessory drives are taken from the nose cone, above and below the engine core.
888:
837:
509:
199:
333:
915:
707:
493:
304:
1015:
808:
778:
748:
677:
207:
105:
or designs with centrifugal compressors, it may be placed ahead of the compressor.
973:
590:
559:
489:
135:
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192:
184:
23:
1050:
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738:
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380:
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188:
176:
castings. Separate machined mounting pads are provided for each accessory.
160:
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858:
702:
672:
570:
562:
309:
244:
173:
39:
629:
555:
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117:
26:
turboshaft engine. The accessory drive is the large casting on the top.
449:
1025:
883:
733:
687:
624:
219:
180:
102:
98:
999:
758:
697:
619:
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361:
359:
357:
355:
243:
There may be a number of fuel pumps: low pressure, high pressure,
19:
609:
35:
423:
411:
352:
340:
783:
634:
43:
drives on large engines handle between 400–500 hp.
963:
270:
High-pressure air compressor (undercarriage actuation, etc.)
554:
255:, often one for engine systems and one for the aircraft
179:
The drive within the casing is provided by a train of
234:
Some of the accessories that may be driven include:
483:
467:
455:
429:
417:
365:
346:
931:Engine-indicating and crew-alerting system (EICAS)
964:Full Authority Digital Engine/Electronics (FADEC)
514:The Aircraft Gas Turbine Engine and its Operation
206:company, who were making drive gearboxes for the
1048:
381:Pratt & Whitney, Aircraft Gas Turbine Engine
921:Electronic centralised aircraft monitor (ECAM)
540:
261:to maintain a constant frequency AC generator
376:
374:
926:Electronic flight instrument system (EFIS)
547:
533:
391:
389:
371:
247:pump and also a speed-sensitive governor
159:
134:
85:
50:
18:
443:"How a jet engine runs on its "nerves""
1049:
386:
164:Sectioned accessory drive on top of a
67:
528:
520:. pp. 3-45–3-47. P&W 182408.
401:Introduction to Aircraft Power Plants
75:
63:
130:
155:
81:
13:
14:
1073:
794:Thrust specific fuel consumption
518:United Technologies Corporation
477:
461:
843:Propeller speed reduction unit
435:
322:
229:
1:
332:. GE Aviation. Archived from
315:
46:
213:
66:that couples the drive to a
7:
754:Engine pressure ratio (EPR)
293:
10:
1078:
1021:Auxiliary power unit (APU)
645:Rotating detonation engine
1008:
982:
949:
906:
851:
830:
821:
721:
653:
583:
569:
300:Components of jet engines
729:Aircraft engine starting
492:. 1986. pp. 65–71.
90:Internal gearbox of the
605:Pulse detonation engine
468:Rolls-Royce, Jet Engine
456:Rolls-Royce, Jet Engine
430:Rolls-Royce, Jet Engine
418:Rolls-Royce, Jet Engine
366:Rolls-Royce, Jet Engine
347:Rolls-Royce, Jet Engine
202:in advertising for the
799:Thrust to weight ratio
769:Overall pressure ratio
764:Jet engine performance
683:Centrifugal compressor
600:Gluhareff Pressure Jet
484:"7 Accessory drives".
330:"Engine Vocabulary: A"
168:
144:
94:
59:
27:
1062:Jet engine technology
1036:Ice protection system
804:Variable cycle engine
774:Propulsive efficiency
264:Lubricating oil pumps
163:
138:
89:
54:
38:that forms part of a
22:
936:Flight data recorder
693:Constant speed drive
673:Afterburner (reheat)
259:Constant Speed Drive
1057:Aircraft components
510:Pratt & Whitney
458:, p. 124, 126.
397:"Accessory Systems"
166:Rolls-Royce Pegasus
140:de Havilland Goblin
116:Direct drive, by a
92:Rolls-Royce Pegasus
16:Gas turbine gearbox
838:Propeller governor
200:Boris Artzybasheff
169:
145:
120:on the main shaft.
95:
60:
28:
1044:
1043:
916:Annunciator panel
902:
901:
817:
816:
708:Propelling nozzle
305:Fuel control unit
218:In some engines,
195:to support them.
131:Radial driveshaft
68:radial driveshaft
1069:
1031:Hydraulic system
1026:Bleed air system
1016:Air-start system
879:Counter-rotating
828:
827:
809:Windmill restart
779:Specific impulse
749:Compressor stall
678:Axial compressor
581:
580:
549:
542:
535:
526:
525:
521:
503:
471:
470:, pp. 70–71
465:
459:
453:
447:
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439:
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427:
421:
415:
409:
408:
403:. Archived from
393:
384:
378:
369:
363:
350:
344:
338:
337:
326:
208:Westinghouse J40
156:External gearbox
82:Internal gearbox
76:external gearbox
64:internal gearbox
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1071:
1070:
1068:
1067:
1066:
1047:
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1004:
987:
978:
974:Thrust reversal
951:Engine controls
945:
908:
898:
874:Contra-rotating
847:
813:
717:
663:Accessory drive
655:
649:
591:Air turborocket
573:
565:
553:
512:(August 1988).
500:
480:
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474:
466:
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383:, pp. 3–45
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341:
328:
327:
323:
318:
296:
232:
216:
185:roller bearings
158:
142:
133:
84:
74:that drives an
56:Turbomeca Adour
49:
32:accessory drive
17:
12:
11:
5:
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894:Variable-pitch
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869:Constant-speed
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576:jet propulsion
567:
566:
552:
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522:
505:
504:
498:
486:The Jet Engine
479:
476:
473:
472:
460:
448:
434:
422:
410:
407:on 2015-03-26.
385:
370:
351:
339:
336:on 2012-02-21.
320:
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314:
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307:
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295:
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287:
286:
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277:
276:Engine starter
274:
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268:
267:Hydraulic pump
265:
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256:
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240:
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228:
215:
212:
193:thrust bearing
157:
154:
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83:
80:
48:
45:
24:Klimov TV3-117
15:
9:
6:
4:
3:
2:
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1024:
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1019:
1017:
1014:
1013:
1011:
1009:Other systems
1007:
1001:
998:
996:
993:
992:
990:
986:and induction
985:
981:
975:
972:
970:
967:
965:
962:
960:
957:
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954:
952:
948:
942:
941:Glass cockpit
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745:
742:
740:
739:Brayton cycle
737:
735:
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727:
726:
724:
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714:
713:Turbine blade
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499:0-902121-04-9
495:
491:
487:
482:
481:
469:
464:
457:
452:
444:
438:
432:, p. 70.
431:
426:
420:, p. 69.
419:
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406:
402:
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377:
375:
368:, p. 67.
367:
362:
360:
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349:, p. 65.
348:
343:
335:
331:
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321:
311:
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301:
298:
297:
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284:
282:sensor drives
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204:Avco Lycoming
201:
196:
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189:Helical gears
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57:
53:
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41:
37:
33:
25:
21:
995:Flame holder
969:Thrust lever
959:Autothrottle
789:Thrust lapse
744:Bypass ratio
662:
571:Gas turbines
563:gas turbines
513:
485:
478:Bibliography
463:
451:
437:
425:
413:
405:the original
400:
342:
334:the original
324:
288:
233:
217:
197:
178:
170:
150:
146:
111:
107:
96:
71:
61:
31:
29:
909:instruments
864:Blade pitch
859:Autofeather
703:Nose bullet
556:Jet engines
490:Rolls-Royce
445:. Feb 1953.
310:Nose bullet
245:afterburner
230:Accessories
174:light alloy
40:gas turbine
1051:Categories
852:Principles
831:Components
823:Propellers
722:Principles
668:Air intake
656:components
654:Mechanical
630:Turboshaft
316:References
280:Tachometer
253:Generators
181:spur gears
118:bevel gear
103:turboprops
72:towershaft
47:Components
884:Proprotor
734:Bleed air
688:Combustor
625:Turboprop
238:Fuel pump
224:cabin air
220:bleed air
214:Bleed air
99:combustor
1000:Jet fuel
889:Scimitar
759:Flameout
698:Impeller
620:Turbojet
615:Turbofan
596:Pulsejet
560:aircraft
294:See also
210:engine.
988:systems
610:Propfan
36:gearbox
907:Engine
784:Thrust
640:Rocket
635:Ramjet
496:
584:Types
101:. In
34:is a
984:Fuel
574:and
558:and
494:ISBN
30:The
70:or
1053::
516:.
488:.
399:.
388:^
373:^
354:^
78:.
598:/
548:e
541:t
534:v
502:.
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