CA1118370A - Emergency oil/mist system - Google Patents

Abstract

Inventors: Frank Salvana Arnold Junker Assignee: Avco Corporation Atty. Docket: L-526 EMERGENCY OIL/MIST SYSTEM
Abstract of the Disclosure An emergency oil/mist system is embodied in the main lubrication system for a bearing or gear box assembly of a gas turbine engine, and includes an auxiliary reservoir interconnected between the main source of pressurized lubricant and an air aspir-ating nozzle which is capable of either providing a stream of oil to the bearing, or a mist of lubricant to the bearing. A source of pressurized air is connected to the air aspirating nozzle through a control piston valve, and the latter also is provided in a vent line extending between the auxiliary reservoir and the atmosphere. During normal operation of the main lubrication system, the source of pressurized oil is connected through the auxiliary reservoir to the nozzle for providing a stream of lubri-cant to the bearing. Upon failure of the source of pressurized lubricant, the control piston valve is actuated so as to connect the auxiliary or emergency lubricant reservoir to the atmosphere by the vent conduit, and simultaneously connect the source of pressurized air to the air aspirating nozzle. The pressurized air passing through the nozzle aspirates or draws oil from the emergency reservoir to provide a spray or mist of lubricant to the bearing. The vent assures that the oil in the auxiliary reservoir is withdrawn at a controlled rate, thereby providing a spray of lubricant to the bearing for a limited period of time to enable the engine to maintain its operation. The emergency system produces an ultrasonic impingement of the oil as it leaves the air aspirating nozzle so as to create extremely small drop-lets of uniform distribution of oil on the bearing.

Description

``` 3~18371~
Il EMERGENCY OIL/MIST SYSTEM
1 The subject invention relates to an emergency oil/mist

2 il system embodied in the main lubrication system for a bearing

3 ,l or gear box assembly of a gas turbine engine, and more parti-

4 ¦l~ cularly, to an emergency lubrication supply system for f, providing a pressurized spray of lubricant so as to create 6 ¦~ extremely small droplets of a uniform distribution of oil on 7 ¦I the bearing for a limited period of time after failure of 8 ¦I the main lubrication supply system.
9 ¦¦ In gas turbine engines, as employed in high speed air-10 ¦ oraft, the rotational shafts are journalled within bearing 11 ~ b~xes for rotation with respect to the engine frame members, 12 I and thus the bearings must be continually supplied with a 13 stream of lubricant. Generally, the main lubrication supply 14 I system includes a large reservoir of lubricant, and pump means 15 l are provided for distributing the lubricant through conduits 16 ¦ to the various bearings and gear box assemblies. The latter 17 are usually housed wlthin enclosed sumps such that the oil 18 j collected at the bottom of each sump is returned to the main 19 reservoir by scavenging devices, after which the lubricant 20 ¦ is again pumped in a continuous circuit back to the bearings 21 ~ or gea~ box assemblies. As is readily apparent, it is of 1 22 ~ extreme importance that the movable bearings or gear box 23 ¦ assemblies are aontinuously lubricated in order to prevent 24 premature failure by seiaing of the relatively mo~able parts. f The v~rious components of the main lubrication supply system, 26 because of their size, are generally located external to the 27 engine ca ing ~here they are susceptible to damage, a~ 1n I
i ~ ~118370 1 l, the case of a gas turbine engine as embodied in a military 2 ~l aircraft where the exposed components of the main lubrica-3 '~ tion supply system are vulnerable to enemy fire. As is 4 i readily apparent, in the case of a rupture or puncture in 'I the oil lines or components in the main lubrication supply 6 ~~ system, the oil pressure and flow to the individual bearings 7 ~l or gear box assemblies will be quickly interrupted, and con-8 ~, tinued operation o~ the gas turbine engine will rapidly 9 11 result in seizure of the bearings and/or gear box assemblies, 11 resulting in engine failure.
11 ¦ Heretofore in order that the gas turbine engine and the 12 ¦ aixcraft may continue to safely operate for a limited period 13 ~ of time after rupture or puncture of a component in the main 14 I lu~rication supply system, an emergency oil reservoir has been ¦
suggested for providing lubricant to a lubricated part for a 16 limited duration after-failure of the main lubrication supply 17 ~ system. The inclusion of the emergency oil reservoir is of ,, 18 critical importance particularly for military aircraft opera-19 ting under combat conditions, and generally it has been suggested that a plurality of emergency oil reservoirs be 21 strategically located throughout the aircraft gas turbine 22 ¦ engine in the vicinity of the bearings and gear box assemblies.j 23 I Generally each e~ergency oil reservoir is filled from the main I
24 oil supply system and may include either a gravity feed drain 25 ~ or an air pressure means for supplying a stream of oil to 26 the bearings, with the supply of oil from each emergency 27 ¦ re~en~oLr e~ng generally closed off by a series of check ~1~837C) 1 valves during normal operation. In the event of a loss of 2 l oil pressure or supply, manual or automatic actuation of the 3 1 check valves is required to open the supply of emergency oil.
4 ¦¦ The disadvantage of such an emergency supply system is that ~I closing off of the emergency oil reservoirs during normal 6 ~i eng~ne operation results in oil stagnation which gradually 7 !l leads to h~at degradation of the oil, and the gravity feed 8 ~ system of most conventional emergency oil supply systems may 9 ~I not provide a sufficient stream of air to adequately lubricate i ¦ the contacting surfaces of the lubricated parts and does not 11 ~ supply a cooling air flow to the lubricated parts.
12 ~t has also been known to provide an emergency lubrica-13 . t~on supply system.inlcuding an oil reservoir in substantial 14 .p~oximity to the.lubricated parb, with conduit means exten-ding fxom the emergency reservoir having an outlet located 16 aa jacent the bearing to be lubricated. Pressurized air flow 17 is continuously provided over the emergency reservoir outlet 18 ` means for creating a suction therein for drawing lubricant 19 through the conduit both during normal operation, and during emergency operation when the main oil source has been disabled.
21 Accordingly, with this emergency lubrication supply system, 22 lubricant within the.emergenay reservoir is continually being 23 depleted during normal operation of the aircraft engine.
24 ~ ¦ ~ccordingly, it i:s an object of the subject invention ¦ to provide a new and improved emergency oil supply system for 26 ¦ provLding, for a limited duration after failure of the main 2 7 lub~ lca~i n supply zyutez, a ~ e ssurized spray of lubr i-ant : ', , I i :

` 111837~ ~

1 `/ mist to the bearing in the form of small droplets of a uniform 2 , distribution of oil on the bearing for preventing seizure of 3 ,I the relatively movable parts, thereby precluding catastrophic 4 1, engine failure.
1l It is a further object of the subject invention to 6 , provide an emergency oil supply system wherein the emergency 7 1ll oil reservoir is disposed in the circuit extending between 8 il ,the main lubrication supply and the bearing, such that the 9 ¦i oil within the emergency reservoir is continually recircula-ili ted, and thus is not susceptible to becoming stagnant.
11 I It is still a further object of the subject invention to 12 ~ provide an emergency oil supply system wherein the oil is 13 ¦ aspirated from an emergency oil reservoir and is sprayed under 14 ~I high,pressure in order to form extremely small droplets of oil ~hich are unifo~mly distributed over the bearing, thereby 16 , expanding the period of time during which the emergency oil 17 system is operative.
18 It is another object of the subject invention to provide 19 an emergency oil supply system which is fully operative fol-20 I lo~ng failure o~ the main lubrication supply system.
21 The above and other objects and advantages of the inven-22 tion ar,e ac,hieved by the subject emergency oil/mist system 23 embodied-in the main,lubrication system of an aircraft gas 24 ¦ turbine engine and including an auxiliary reservoir which is 25 ll operatively conneated in the conduit means extending between 26 ¦~ the main source of pressurized lubricant and the nozzle for 27 applying oil onto a bearing or gear box assembly. ~he noszle 'i . . , 1 is capable of either directing a stream of oil to the bearing 2 ` (when the main lubrication system is fully operative) or a 3 ~ mist of lubricant comprised of lubricant aspirated from the 4 fl emergency reservoir and high pressure air (when the main (~ supply lubrication supply system has failed). A control 6 ~I piston valve interconnects the emergency reservoir to an 7 ~ atmospheric vent, and also connects a source of pressurized 8 ~¦ a~r to the air aspirator nozzle. Upon failure of the main 9 ~l lubrication system, the control valve is actuated such that ~ pressurized air is provided to the nozzle and, by air aspir-~ ation, withdraws oil remaining in the emergency reservoir.
12 ! The ~alve also connects the emergency reservoir to the 13 ~ atmospheric vent thereby providing an effective control on 14 ¦ the amount of oil aspirated from the emergency reservoir. By l this arrangement, the emergency oil/mist lubrication system 16 l prGvides an ultrasonic impingement of droplets of oil as it 17 leaves the nozzle, thereby creating extremely small droplets 18 ¦ of uniform distribution of oil on the bearing or gear box 19 assembly. Actuation of the control valve may be effected by the pressure balance piston type or solenoid valves triggered 21 by low oil pressure in the main supply system or by excessive 22 bearing or gear box temperatures.
23 Further objects and advantages of the invention will 24 become apparent from a reading of the following detailed des-~ cription of a preferred embodiment of the subject invention 26 ¦ taken in conjunction with the drawings in which:
~ ', ' ~183qO
~ i 1 ~ FIG. 1 is a schematic view of the emergency oil/mist 2 , lubrication system of the subject invention when the main 3 1 lubrication system is fully operational;
4 , FIG. 2 is a schematic illustration of the control valve ~ of the subject invention ~hen the main lubrication supply 6 I s~stem is fully operational as-in FIG. l;
7 I FIG. 3 is a schematic illustration of the subject 8 lii, e~ergency oil-~mist lubrication system when the main supply g ll system is disabled and the emergency lubrication supply I system is fully operational~ and 11 ¦ FIG. 4 is a schematic illustration of the control valve 12 ~ of the subject invention during the time when the emergency 13 lu~rication supply system is operational as in FIG. 3.
14 Referring to FIG5. 1 and 2, the lubrication supply lS system of the subject invention is generally designated by 16 the numeral 10 and is operative to provide lubricant to a 17 . bearing 12 which supports rotating shaft 14 of, for example, 18 a gas turbine engine of an aircraft. The bearing 12 may be 19 encased within a bearing cavity (.not shown) having an oil scavenging line for recirculating lubricant provided to the 21 bearing 12 to the ma~in reservoir (.not shown~ for the lubrica-22 t~on supply system 10. Although the lubrication supply system 23 of the subject invention is described in relation to an engine 24 bearing, it is under~tood to have substantially broader appli-25 - cation and may be applied to any engine part requiring 26 lubricat~ n.

1 ' l ~118370 l . The lubrication supply system 10 includes a main source 1 of pressurized fluid, such as from a main supply reservoir 3 i~ (not shovn) and suitable pump means (not shown) which are 4 1 indicated in FIG. l as "oil flow" to the conduit 20 which ~ extends to an air aspirating nozzle 22. The latter is loca-6 1, ted in proximity to the bearing 12 for providing a stream 26 7 I o~ oil to the bearing 12. The air aspirating nozzle 22 is of 8 I generally tubular construction and includes two elongated 9 passageways 28 and 30 lèading to an enlarged outlet 32.
l Conduit 20 is connected to passageway 28 and during normal ll . operation of the lubrication supply system 10, pressurized 12 ~ oil is passed through the conduit 20, through passageway 28 13 ¦ of nozzle 22, and onto the bearing 12.
14 ~ ~rhe emergency oil/mist lubrication system of the sub-¦ ject invention is embodied in and forms a portion of the 16 ¦ lubrication supply system 10 and includes an emergency oil 17 ¦ reservoir 40 that is disposéd in series in the conduit 20.
18 ~ kccordingly, during normal operation of the lubrication 19 ¦ supply system 10, pressurized lubricant provided through the ¦ conduit 2;0 is likewise passed through the emergency oil 21 ¦ reservoir 40 and then to the passageway 28 of the air aspira-22 ¦ ting noz~le 22, and is sprayed a~ stream 26 onto the bearing 23 l 12. Accordingly, the lubricant within the emergency oil 24 ¦ - reservoir 40 is constantly being replenished and depleted, 25 ¦ thereby precluding. stagnation of lubricant within reservoir 26 ¦ 40 aue to heat developed within the engine. Preferably, 27 emergency oil reservoir 40 is located in proximity to the 28 : bea ing 12, and is of a zize in order to hold a q:antity of !

1~8370 . . .
1 , approximately 100 cubic centimeters of oil whereby the 2 ' emergency oil reservoir 40 is of sufficiently small size to 3 ' be readily positioned within the confines of the engine 4 ,, housing. The emergency oil/mist lubrication system also '', includes an emergency control valve means 50 (see FIGS. 1 and 6 ~ 2) which may be of the piston valve type. Piston ~alve 50 7 ~I may be of the pressure balance piston type and includes an 8 1! outer cylindrical housing 52 in which piston 54 is slidably 9 ~ movable, One end 56 of the cylindrical housing 52 includes an opening 58 which is in communication via conduit 21 with 11 the source of pressurized o~l from the main supply reservoir.
12 Opening 58 leads into th~ inner chamber of the cylinder and 13 1~ be~rs against the let hand end 60 of piston 54. The opposite 14 end of piston 54 includes an extension 62 having a single I through aperture 64. Cylindrical portion 52 of the piston 16 I valve includes two through passageways 70 and 72, as well as 17 ¦ an a~perture 53 interconnecting passageway 70 with the chamber 18 on the right hand end of piston 54.
19 ~ During normal operatïon of the lubrication supply system ¦ 10, the pressurized oil flow from the main supply source bears 21 ¦ against the end 60 of the piston æuch that the piston is 22 seated as æho~n in FIG. 2 and the piston extension 62 effec-23 t~vely closes off the passageways 70 and 72. At such time, 24 the force of the pressurized oiI against the end 60 of piston 54 i6 greater than the force o the pressurized air applied to 26 t~e right hand end of piston 54 through aperture 53. The 27 ¦ upper end 70A of passageway 70 is connected to a source of 28 presSuriz d air vie suppiy conduit 84, while the lo~er por-_ ~ _ 111~37~ ~
.
1 ~ tion 70B of passageway 70 is connected via a conduit 86 to !, 2 l the elongated passageway 30 in the air aspirating nozzle 22.
3 The upper portion 72A of passageway 72 is connected via a 4 j, conduit 80 to the atmosphere, while the lower portion 72B .
'~ is connected via line 82 to the emergency oil reservoir 40.
6 ~1 As indicated above, during normal operation of the main 7 ~ lubrication/supply system lO, the extension 62 of the piston 8 ¦ 54 is disposed as shown in FIG. 2.so as to block passageways 9 ¦ 70 and 72, thereby preventing the emergency oil reservoir ~ from being vented to the atmosphere via conduits 80 and 82, 11 and also preventing the source of pressurized air flow from .12 ¦ condu~t 84 from being provided to the air aspirating nozzle 13 1 22.
14 In the event of an emergency, such as a puncture or rupture in the main oil reservoir or the pump means for pres- I
16 surizing the main source of lubricant flaw, pressure and flow 17 in the c.onduit 20 will rapidly decrease. The possibility of 18~ a rupture-or puncture in any component of.the main oil supply 19 .system is of particular conaern to military aircra~t flying j combat missions where the oil supply components, which are 21 generally situated external to the engine casing, are more 22 vulnerable to damage from enemy fire. Without lubrication, 23 . it i5 apparent that the high speed rotating shaft 14 would 24- quickly seize, or the bearing 12 will become damaged thereby 25 ~ possibly resulting.in catastrophic engine failure. The 26 emergency oil/mist supply sytem of the subject invention is 1.
27 designed to provide a limLted period during which an emergency _ 9 _ 37C~

1 ultrasonic spray of high pressure lubrlcant is provided to 2 . the bearing 12, as well as pressurized air flow capable of 3 ~ cooling the bearing 12 during the limited emergency period of 4 ~. the pressurized lubrication spray.
" During an emergency condition, the pressurized flow 6 il provided to the opening 58 of valve 50 rapidly decreases, 7 ~l. thereby enabling the pressure balance piston 54 to be actuated 8 il toward the left, to the position as.illustrated in FIG. 4, by 9 ~¦ virtue of the pressurized ~low provided through aperture 53.
~¦ Alternatively, actuation of piston valve 50 may be solenoid 11 ~ controlled in response to the rapid decrease in pressure of 12 ~ the main oil supply or a temperature sensor may be provided in 13 - ¦- the vicinity of the bearing.12 and may provide a triggering 14 ! signal to a suitable solenoid operated valve for actuating ~ . piston 54 to the position as shown in FIG~ 4. At such time, 16 as shown in.FIGS. 3 and 4, the emergency oil/mist lubrication 17 system i8 operational, and the passageways 70 and 72 are 18 opened, ~ith aperture 64 being aligned with passageway 70.
19 ¦ At such t~me, the emergency oil reservoir 40 is vented to I the atmosphere via conduits 82 and 80 which extend through 2I passage~ay 72. In addition, pressurized air flow is provided 22 ¦ via conduit 84, through.passageway 70 to aperture 53 and also 23 : ¦ to conduit 86 leading to the passageway 30 in the air aspir-24 ating nozzle 22. The high pressurized air flowing through ~ t~he passageway 30 emerges into the enlarged outlet 32 thereby 26 I .effectively creating a partial vacuum in the nozzle 22 for 27 ~ aspirating lubricant from the emergency oil reservoir 40 via Il ., Il -10- 'I

33~70 .
l conduit 20 and passageway 28. The fact that the emergency 2 oil reservoir 40 is vented to the atmosphere assures that the 3 il withdrawal of the emergency oil from the reservoir 40 is at 4 ' a controlled rate in order to prolong emergency lubrication , to the bearing 12 for a sufficient period of time to enable 6 i the pilot of the aircraft to make the necessary emergency 7 1I maneuvers. The intermixture of the pressurized air and the 8 ~l oil aspirated from the emergency oil reservoir 40 results in g !l a fine mist of small droplets of oil 90 (see FIG. 3) provided lO ~I to the bearing 12. The emergency lubrication mist 90 auto-matically continues to flow and impinge on the contacting 12 ¦I bearing surfaces 12 at a slow metered rate until the emergency 13 ~¦ o~l reservoir 40 is emptied. It is estimated that with an 14 ~ emergency oil reservoir 40 having a capacity of approximately lS ~ lO0 cubic centimeteræ of oil, the emergency oil/mist system 16 ~ill be capable of operating for approx~matèly one-half of 17 ll an hour during which time high pressurized mist 90 provided 18 ~¦ to the bearing 12 would be sufficient lubrication for continued l9 ll operation of the bearing 12. In addition, the pressurized air is effective to aid ln cooling of the bearing.
21 Accordingly, there is provided a new and improved ', 22 e~ergency oil~mist lubrication system which is formed as an 23 ~ integra~l part of the main lubrication system of a gas turbine 24 ¦ engine and is designed to function as a mist lubricant gener-¦ ato~ in the event of failure of the main lubrication system.
26 .~ The e~ergency oil~mist lubrication system may be employed for 27 ~¦ ~earings or gear box assemblies of a gas turbine engine, and 37~
, `, 1 ~ the auxiliary or emergency reservoir has sufficient capacity 2 `~ to provide lubrication to the bearing assem~ly for approxi-3 ~ mately thirty minutes following failure of the main lubrica-4 ' tion system. The subject system produces an ultrasonic impingement of the oil as it leaves the air aspirating 6 1I nozzle 22 thereby creating extremely small droplets of 7 ¦~ uniform distribution of lubricant over the bearing. In 8 ~l addition, the flow of pressurized air to the bearing is 9 j effecti~e in cooling the bearing during the emergency ~l operation. The emergency oil/mist supply sytem can be 11 il actuated by a pressure balance piston-type valve or a suit-12 ¦ able solenoid valve triggered by low oil pressure in the main 13 ~ supply system, or a solenoid valve which is triggered by suit-14 able sensors for sensing excessive bearing temperatures.
~hile the invention has been described with respect to 16 a specific embodiment thereof, it is readily apparent that 17 ~ various modifications, alterations, or the like may be appa-18 rent to those skilled i~ the art, and thus the invention is 19 not to be limited by the illustrative embodiment, ~ut by the spirit and scope of the fo1iowing appended claims.

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Claims (9)

1. WHAT IS CLAIMED IS:
   l. An emergency lubricant/mist system for providing a pressurized spray of lubricant to a lubricated part for a limited period of time after failure of a main lubrication system comprising:
   a source of pressurized lubricant;
   air aspirating nozzle means directed to provide either a stream of lubricant or a spray of lubricant to the lubricated part;
   conduit means interconnecting said source of pressurized lubricant to said nozzle means;
   an emergency lubricant reservoir provided in said conduit means intermediate said source of pressurized lubricant and said nozzle means;
   atmospheric vent means;
   a source of pressurized air;
   control means interconnecting: (1) said atmospheric vent means with said emergency lubricant reservoir; and (2) said source of pressurized air with said air aspirating nozzle means; said control means being operatively connected to said source of pressurized lubricant whereby when the main lubrication system is operational, said control means is operative to inhibit the flow of pressurized air from said source of pressurized air to said air aspirating nozzle means and to inhibit said emergency lubricant reservoir from being vented to the atmosphere, whereas upon failure of the main lubrication system, said control means is effective to vent the emergency lubricant reservoir and simultaneously allow pressurized air to be provided to the air aspiration nozzle means from the source of pressurized air, such that the pressurized air passing through the nozzle means is effective to aspirate lubricant from the emergency lubricant reservoir to create a pressurized spray of lubricant to said lubricated part.
2. 2. An emergency lubricant/mist system for providing a pressurized spray of lubricant to a lubricated part for a limited period of time after failure of a main lubrication system as in claim 1 wherein said control means comprises a piston valve including an outer cylindrical casing and a piston slidably mounted therein, said cylinder including a plurality of aligned passageways extending therethrough, which passageways are connected to said atmospheric vent means, said source of pressurized air, said emergency lubricant reservoir, and the air aspirating nozzle means, with the position of the slidable piston being a function of the flow of pressurized lubri-cant.
3. 3. An emergency lubricant/mist system for providing a pressurized spray of lubricant to a lubricated part for a limited period of time after failure of a main lubrication system as in claim 1 wherein said air aspirating nozzle means is gen-erally tubular and includes two passageways leading to an en-larged outlet main passageway, with one passageway connected to said conduit means extending to the source of pressurized lubri-cant, while the other passageway is connected to the conduit ex-tending to the source of pressurized air.
4. 4. An emergency lubricant/mist system for providing a pressurized spray of lubricant to a lubricated part for a limited period of time after failure of a main lubrication system as in claim 1 wherein the volume of the emergency lubricant reservoir is approximately 100 cubic centimeters.
5. 5. An emergency oil/mist system for providing a pressurized spray of oil to a lubricated part for a limited period of time after failure of a main lubrication system comprising:
   a source of pressurized oil;
   an air aspirating nozzle for providing oil to the lubricated part, said nozzle including two generally parallel passageways leading to an enlarged outlet for said nozzle;
   conduit means interconnecting the source of pressurized oil to said nozzle;
   an emergency lubricant reservoir disposed in the conduit means intermediate said source of pressurized oil and the nozzle;
   atmospheric vent means;
   a source of pressurized air;
   a piston control valve interconnecting:
   (1) said atmospheric vent means with said emergency lubricant reservoir; and (2) the source of pressurized air with the air aspirating nozzle, with the piston of said piston control valve being actuated in response to the pressurized lubricant in the conduit means such that when the main lubrication system is operational, the piston is operative to inhibit interconnection between said atmospheric vent means and the emergency lubricant reservoir, as well as inhibit inter-connection between the source of pressurized air with the air aspirating nozzle, whereas, upon failure of the main lubrication supply system, the piston is actuated so as to interconnect the emergency lubricant reservoir with the atmospheric vent means and simul-taneously interconnect the source of pressurized air with the air aspirating nozzle such that the pressurized air passing through one of the passageways in the nozzle is effective to aspirate oil from the emergency lubricant reservoir to create a pressurized mist of lubricant which is sprayed out of the enlarged nozzle outlet for providing lubricant to the lubricated part, as well as providing cooling pressurized air flow to the lubricated part.
6. 6. An emergency oil/mist system for providing a pressurized spray of oil to a lubricated part for a limited period of time after failure of a main lubrication system, as in claim 5 wherein the volume of the emergency lubricant reservoir is approximately 100 cubic centimeters.
7. 7. An emergency oil/mist system for providing a pressurized spray of oil to a lubricated part for a limited period of time after failure of a main lubrication system, as in claim 5 wherein the piston control valve includes an outer cylin-drical casing and a piston slidably mounted therein, said cylin-drical including a plurality of aligned passageways extending therethrough, which passageways are connected to said aspirating vent means, said source of pressurized air, said emergency lubri-cant reservoir, and the air aspirating nozzle.
8. 8. An emergency oil/mist system for providing a pressurized spray of oil to a lubricated part for a limited period of time after failure of a main lubrication system, as in claim 7 wherein the piston control valve is of the pressure balance type and the position of the slidable piston is re-sponsive to the oil pressure drop and the introduction of the pressurized air source acting on the pressure balance piston.
9. 9. An emergency oil/mist system for providing a pressurized spray of oil to a lubricated part for a limited period of time after failure of a main lubrication system, as in claim 7 wherein the position of the slidable piston is re-sponsive to the temperature of the lubricated part.