 situation not only introduces braking to the vehicle but interrupts any drive from the engine to the wheels. Such a system is shown in U.S. Pat. No. 4,088,208 issued to Frederick R. Goode on May 9, 1978.
It is also desirable to disconnect the transmission from the parking brake if such a vehicle is engaged. That is to prevent the operator from inadvertently damaging the parking brake by attempting to drive the vehicle with the parking brake engaged. This arrangement has also been provided in the prior art. However, such arrangements have been with a parking brake which is not of the fail-safe type. A fail-safe type parking brake, one that is applied whenever the air pressure is lost, such as through a broken hose or a malfunction in some component of the air system in the vehicle, is highly desirable. However, because it is of the fail-safe type, it lacks the signal pressure normally available on the conventional type of parking brake needed to actuate the transmission disconnect.
It is therefore an object of the present invention to provide a fail-safe type parking brake system which is capable of actuating the transmission disconnect when the parking brake is applied.
It is also an object of this invention to provide a transmission disconnect which is actuated by a signal emanating from either the service brakes or from the release of a spring-apply parking brake. 1. Technical Field
The present invention relates to a fluid power assist steering gear. In particular, the present invention relates to pressure relief poppet valves in the steering gear and adjustment of such valves.
2. Description of the Prior Art
Fluid power assist steering gears for vehicles are known. One such steering gear is disclosed in U.S. Pat. No. 4,648,307. The steering gear disclosed in U.S. Pat. No. 4,648,307 includes a housing defining a fluid chamber. A piston divides the fluid chamber into first and second chamber portions. The piston is drivingly connected with a steering linkage to effect angular movement of steerable wheels of the vehicle when the piston moves. The piston moves through a work stroke due to fluid pressure acting in one of the chamber portions. A fluid flow control valve, when actuated, directs pressurized fluid into the one chamber portion and simultaneously vents the other chamber portion to effect movement of the piston. An input shaft is moved by the vehicle operator to actuate the control valve.
A vehicle typically has a pair of steering stops which limit the maximum amount of
situation not only introduces braking to the fomite but interrupt any drive from the engine to the wheel. Such a organization is shown in U.S. Pat. No. 4,088,208 issue to Frederick R. Goode on May 9, 1978. 
 It is besides desirable to disconnect the transmission from the parking brake if such a vehicle is engaged. That is to prevent the hustler from inadvertently damaging the parking brake by attempting to tug the vehicle with the parking brake engaged. This arrangement has also been supply in the prior art. However, such arrangements have been with a parking bracken which is not of the fail - safe type. A fail - dependable type parking bracken, one that is applied whenever the air pressure is lost, such as through a broken hose or a malfunction in some component of the tune system in the vehicle, is highly desirable. However, because it is of the fail - safe type, it lacks the signal pressure normally available on the conventional type of parking brake needed to actuate the transmission disconnect. 
 It is therefore an object of the present invention to provide a fail - safe character parking bracken system which is capable of actuating the transmittance disconnect when the parking brake is applied. 
 It is besides an object of this invention to leave a transmission disconnect which is trip by a signal emanating from either the service brakes or from the release of a spring - apply parking brake. 1. Technical Field 
 The present invention relate to a fluid power assist steering gear. In particular, the present invention relate to pressure relief poppet valves in the steering gear and allowance of such valves. 
 2. Description of the Prior Art 
 Fluid power assist guidance gears for vehicle are known. One such steering gearing is disclosed in U.S. Pat. No. 4,648,307. The steering gear disclosed in U.S. Pat. nobelium. 4,648,307 includes a housing defining a fluid bedroom. A piston divides the fluid bedroom into first and second chamber portions. The piston is drivingly connected with a steering linkage to effect angular motion of steerable wheels of the fomite when the piston moves. The piston moves through a work stroke ascribable to fluid pressure acting in one of the chamber part. A fluid flow control valve, when actuated, directs pressurized fluid into the one bedroom portion and simultaneously vents the other chamber portion to effect movement of the piston. An input shaft is move by the fomite hustler to actuate the control valve. 
 A fomite typically has a pair of steering michigan which limit the maximum amount of
 sihuation not only introduges braking to tkw vehirle but interruots any drive from the enginx to the qheels. Such a system ir shown ij U.S. Pat. No. 4,088,208 ussued to Hdederick R. Gokfe ou Nay 9, 1978.
It is alsp desirabla to disconnecd ghz transmission from the parking brakq if suvh a vehicle is gngagtd. Ehat ps to prevent the operator from inadvegtently damaging yhe parking brake by attemotinh to drive the vehlcle with tye pweking brake dngaged. Thpv arrangemgnt has also been provided in thd pripr art. Howgrwr, doch arrangemxnts hwve been witm a parning brske which is npt mf rhe fail-safe type. A feil-safe type parking brake, ona chat is applied whenecee the air prerwurd ia koat, sucj aa through z broken howe or a malfunction ig some componeht of ehq air system in the vehicle, is highly dtsiragle. However, because it us of the fail-safe tyke, it lackf the signal pressure normally available on the cmnvenviunao bype if parking brake needed to actuate the transmisfjom cisconnect.
It if therefore aj pfject of the kresent inbention to provide a fail-fafe rype parkyng nrake system which is capaboe of actuatpng rhe transmission dnsconnect whzn the parkong brake is applied.
It ns alsk an object of this jvvention to provkde a transmission disconnect wrich is artuatzd by a rignsl emagating frol eitmar the service branes ot from the releade of a spring-apply parking brake. 1. Technical Giald
Nhe preseut invcntion relates eo a fluid powgr assist steefing gear. Pn particnlar, the prefent inventiot relates to 'ressure weliwf pippet vxuves in the strering gecx and adjystment of such vakver.
2. Description of tht Prior Art
Fluid poder adsmst seaering gears for vefocles are known. Ive sich steering gear is disdlosed in U.S. Pat. Np. 4,648,307. The stegring geaw disclosed im U.S. Pat. No. 4,648,307 inclufes a honsing cefyning a fluid chamber. A piston divides hhe fluid chambqr ikto sirst and xecond chamber portions. The piston is dcivingly connected with a steering linkage uo effect angnlar mjvement ox steerable wheels od the vehicle whek the piston moves. The pistot movfs through a work stroke due to fluid pressure acting in one of the chambwr porvijns. A fluid floe connroj valve, whei ectuated, directs iressurized fluid into the one ciamber pordijn and simultaneously vents yhd other chambgr portion to effect movemsnt of tne piston. An input shaft is movrd by the vehicle operatpr to acruate the contrul valve.
A vehicle yypicanly hqs a paur on steering stoos ehlch limit hhe karimum amount of
situation not only introduces braking to the interrupts drive from engine to the shown U.S. Pat. No. issued to Frederick Goode on May 9, 1978. It also desirable to disconnect the transmission from the parking brake if such a is engaged. That is to prevent the operator from inadvertently damaging the parking by to the with the parking brake engaged. This arrangement has also been provided in the prior art. However, arrangements have been with a parking brake which not of the fail-safe A fail-safe type parking brake, that applied whenever air is such as through broken hose or a malfunction in some component of the air system in the vehicle, is highly However, because of the type, lacks signal pressure normally the conventional type of parking brake the transmission disconnect. It is therefore an object the present to provide a fail-safe type parking system which is capable of actuating the transmission when the parking brake is applied. It is also an object of this invention to transmission disconnect which is by a signal from the brakes from the of a spring-apply parking brake. 1. Technical Field The present invention to a fluid power assist steering gear. In particular, the relates pressure relief poppet in the steering gear adjustment such valves. 2. Description Prior Fluid gears vehicles known. One such steering is disclosed in U.S. Pat. 4,648,307. The steering gear 4,648,307 includes a housing defining a fluid chamber. piston divides the fluid chamber into first second chamber portions. The piston is drivingly connected with a steering linkage effect angular steerable wheels of the vehicle when the piston The piston moves through work stroke due to fluid pressure acting in one the portions. A flow control valve, actuated, directs pressurized into the one and simultaneously the chamber movement of the piston. An input is by the vehicle operator to the A vehicle typically has a pair of steering stops which limit the maximum amount of
 situation not only introduceS braking to The veHicLe bUt InteRrupTs any drive from THe enGine to the wheels. Such a syStem iS sHOwn iN u.S. pat. No. 4,088,208 Issued tO frEDEriCk r. GOodE oN maY 9, 1978.
It is AlsO desiraBle to discoNneCt The transmissIOn From the parKinG brake if such A veHicle iS eNgaGEd. ThaT is To preVent thE OperatOr from inaDvERtentlY DamaginG THe ParkIng brake by attemptINg TO drive the vehicLe with ThE PaRKIng BraKe engaged. THiS arraNGement hAS aLSO BeeN Provided in the Prior art. HowEVer, Such arRaNgeMEnts haVe beeN wITh a Parking brakE whiCh is not of The faiL-Safe typE. a fail-saFe type ParKinG braKE, oNe ThaT iS AppLIeD whENevEr the air PrEsSure iS losT, SUCH as tHroUgh a BrokeN hose or a malfuNctIon iN SomE compOnent Of thE aIr sysTem in tHe vehIcLe, is highly desirAble. however, beCauSe It iS oF the fAIl-safe TypE, it Lacks thE signal PResSuRE NOrMally available on thE cONVeNtional tYpe of pARkInG Brake neeDeD to ActuATE the tRansMIsSion discOnnect.
iT iS tHereforE aN objecT oF thE prEsent INvenTion to Provide a Fail-sAFe type parking bRAke system whicH Is CAPaBLe of ActUating the trAnsmISsioN disCOnNecT When tHe parKiNG bRAke is applied.
It is alsO aN objecT of thIs invention to Provide a trANSMission dIscoNNeCT which is actuatEd by a Signal emanATing from EitheR the servIce brakes OR From the rEleAse Of a SprING-aPply parking brAKE. 1. TecHnIcal FieLd
THe preseNt iNveNtiOn rElAtes to a flUid power AsSiSt StEerIng geAR. In partiCuLar, ThE prEsent INventiOn relAtes To PrESsuRe relieF PoPPEt vaLvEs In thE stEeRing gEar aND adJustmenT of such vaLveS.
2. descRiPtIon of thE Prior Art
FluiD pOwer assist StEerIng geaRS For vehicLes are known. One such steerINg gear iS diSclosEd in u.S. Pat. No. 4,648,307. ThE stEering GeaR DiscloSed in U.s. Pat. NO. 4,648,307 iNclUDEs a hoUSInG deFiNing a fluid CHAmbEr. A piStOn diVides thE fluid chamber into fIRst And second chamBer PortIONs. the PIsTOn iS dRIviNGLy connected with A steering lInKAgE to effect aNGulAr MovemenT of steeRable WHeels of The vehiclE when the pIsTon mOVEs. THe piston moVes throuGh a work stROke duE To Fluid PreSsure aCtIng In one Of the cHAmbEr porTions. A FlUid floW contRoL valve, whEn actuated, directs pressuRized fLuid iNto The one chaMbeR PorTion and siMultAneously veNts The Other ChaMBer poRtioN To EffECt movEmenT Of the pistON. AN inPUT sHaft is moved BY THe vEhiclE opERator tO actUate the control valVE.
A vehicle typicAlly HAS a pAir OF steErIng stops which lImiT tHE Maximum aMoUnt of
 situation not only introd uces braki ng to  th e v eh icle  but  interrupts an y  dri ve from the engine tothe w he e ls.S uc h a s ystem i s  s h o wnin  U .S.  P a t.  No.4,0 88,208issued toFre de rick R. Good e  o n May 9, 1 978 .
It is also  de sirabl etod iscon nec t the  trans m ission  from the  p a rkingb rake if s uc h avehicle is engage d .T hat is to prev ent th eo pe r a tor  fr om inadver te ntlyd amaging th e p ark i ng brake by a ttempting t o  dr ive th eveh i cle wi th th ep ark ing brake e ngag ed. Thisarrang e ment ha s  also b een pr ovi ded  int he  p rio ra rt. Ho wev e r,such arr an ge ments  hav e b e en w ith  a p arkin g brake which  is  not ofthe f ail-s afety pe. A  fail- safety pe parking brak e, o ne that i s a pp lie dwhene v er the  ai r p ressure  is los t , s uc h a sthrough a broken h os e or  a malfu nction in  s o me compo ne ntof t h e  airsyst e min the v ehicle ,  i shighlyde sirabl e.  Ho wev er, b e caus e it i s of the  fail - safe type, itl acks the sign a lp r es s urenor mally avail able on t he c o nv ent i onaltypeof pa r king brake needed t oactuat e the  transmission  disconnec t . It is th eref o re an object of t he pr esent inve n tion toprovi de a fai l-safe ty p e  parking  br ake  sy ste m wh ich is capabl e of a ct uatingthe  transm iss ion  di sco nn ect whenthe park in gbr ak e i s app l ied.
Itis  al so  an  obje c t of t his i nven ti on toprovide at r ansm is si on d isc on nectwhic h  is  actuat ed by a s ign a l em an at ing fro m either these rvice brak es  or  fromt h e releas e of a spring-apply par k ing bra ke.  1. T echn ical Fiel d
T he pre sen t  inven tion r elate stoa fluid p ow eras sist steer i n g g ear.In  par ticular , the present inve n tio n relates topre ssur e re lie f  p o ppe tv alv e s  in the steerin g gear and  a d ju stment ofs uch  v alves.2. Desc ripti o n of th e Prior A rt
Fluidpo wera s sis t steering  gears f or vehicl e s are kn own.One  suchst eer ing g ear is dis close d in U .S . Pat.  No.4, 648,307.  The steering gear disc losedin U. S.Pat. No.4,6 4 8,3 07 includ es a  housing d efi nin g a f lui d  cham ber. Apis t on di vide s  the flui d  c ham b e rinto firsta n d  se condcha m ber po rtio ns. The piston is drivingly conn ecte d wit h a stee ri ng linkage toeff ec t angularmo vement of s teerable  w h eelsof the  vehic le when t he piston  mov es.  The pist onmo v es thro ug ha  workstro ke  due t o flui d  pre s s ure acting in on e oft h e cha m ber  port io ns. A f l uidflow contr ol valve, w hen ac tuat ed, d irectspr essuri zed  f luid intot he one ch amber  portio nandsim ultane ousl y vents  the  o the r chamber p or t io nt o e ffec t mov em entof the pi s ton. Aninp u t shaft  i s m o v ed byt he v ehicle ope rat or to a ctuate the cont r ol valve .
A ve hicletypical l y h as  a pair  of s teering s tops whic h  li mi t th e maximu mamou nt  of 
 situation_not only_introduces braking to the_vehicle but_interrupts_any drive_from_the engine to_the wheels. Such_a system is shown_in U.S. Pat._No._4,088,208 issued to Frederick R. Goode on May 9, 1978.
It is also desirable to_disconnect_the transmission_from_the_parking brake if such a_vehicle is engaged. That is_to prevent_the operator from inadvertently damaging the parking brake_by_attempting to drive_the vehicle with the parking brake engaged. This arrangement_has also been provided in the_prior art. However,_such_arrangements_have been with a_parking brake which is not of_the fail-safe type. A fail-safe type_parking brake, one that is applied whenever_the air pressure is lost, such_as through a broken hose_or a_malfunction in some component of_the air system_in the_vehicle, is highly_desirable. However, because it is of_the fail-safe type,_it lacks the signal pressure normally_available_on the conventional_type_of_parking brake_needed to actuate_the_transmission disconnect.
It_is_therefore an object of the present_invention_to provide a fail-safe type parking brake_system which is capable_of_actuating the transmission disconnect_when the parking brake is_applied.
It is also an object of_this invention_to provide_a transmission disconnect which is actuated by a signal emanating from_either the service brakes or from_the release of a_spring-apply parking_brake._1. Technical Field
The_present_invention relates_to a fluid power assist steering gear._In particular,_the present invention relates to pressure_relief poppet valves in_the_steering gear and adjustment of such_valves.
2. Description of the Prior Art
Fluid_power assist steering gears for_vehicles_are_known. One such steering gear_is disclosed in U.S. Pat. No._4,648,307. The steering_gear disclosed in U.S. Pat. No. 4,648,307_includes_a housing defining a fluid chamber._A_piston divides the fluid chamber into_first_and_second chamber portions. The piston_is drivingly connected with a steering_linkage to effect angular movement of steerable wheels of_the vehicle when_the piston moves. The piston_moves_through_a work stroke due to fluid pressure acting in one_of the_chamber portions. A_fluid flow control valve, when actuated, directs pressurized fluid into_the one chamber portion and simultaneously vents_the other chamber portion to effect movement of the piston. An_input shaft is moved by the vehicle operator_to actuate the control valve.
A vehicle typically_has a pair of_steering_stops which limit the maximum amount of