USRE21602E - Hydraulic brake holding apparatus - Google Patents

Description

Oct. 22, 1940. F. DARLING HYDRAULIC BRAKE HOLDING APPARATUS Original Filed Sept. 9, i938 2 Sheets-Sheet 1 RANK LIJARLING Oct. 22, 1940. F. DARLING 21,602

HYDRAULIC BRAKE HOLDING APPARATUS Original Filed Sept. 9, 1938 2 Sheets-Sheet 2' Z 'IJiqlll Reiuued a. 1940 Re, 21,602

HYDRAULIC BRAKE HOLDING APPARATUS Frank L. Darling, Hollyw o Calif., assignor to Wagner Electric Corporation, St. Louis, Mo., a corporation of Delaware Original No. 2,148,190, dated February 21, 1939, Serial No) 229,201, September 9, 1938. Applicatign for reissue June 14, 1940, Serial No. 341, 32

22 Claims.

My invention relates particularly to motor vehicles having hydraulic brakes.

Drivers of automobiles generally have recognized the dangers and inconveniences of having to hold ones foot on the brake pedal while the vehicle has made a temporary stop as for a traftic light. Especially is danger present if the vehicle has stopped while on its way up a bill for then when the driver wishes to start the mam chine rolling forwardly he must shift his foot from the brake pedal to the accelerator pedal and during the interval of shift the car is unbraked and usually begins to roll backwardly a greater or lesser distance, depending on the time required by the operator to shift his foot over from the brake pedal to the accelerator pedal. Some drivers when making short time stops frequently use the clutch as a brake to hold the car from rolling backward, while maintaining a foot also on the accelerator pedal for a quick get-away, with consequent unnecessary wear on the clutch, resulting in expensive relining or clutch replacement repairs.

Again, in going down long hills, the driver not infrequently gets tired of holding his foot in the brake-applying position.

It is therefore an object of the invention to provide a device of a simple, inexpensive, easilyoperated character, which will eliminate all the foregoing objectionable features of present-day practice.

It has also been observed that with hydraulic brakes, a sudden application of foot power to the brake pedal often results in locking the brakes, with resultant shock to the occupants of the vehicle and sometimes causing serious injury due to the occupants of the vehicle being thrown forwardly by the sudden stop.

It is therefore a further object to combine with the brake holding feature of my invention, means to cushion the application of the brakes so as to reduce danger of locking to the minimum.

Further it is an object to improve the apparatus which comprises the subject matter of my application Serial No. 204,902, filed April 28, 1938, now Patent No. 2,133,538, issued October 18, 1938, so as to reduce the cost of manufacture.

Other objects will in part be obvious and in part be pointed out hereinafter.

To the attainment ofthe above objects and ends the invention still further resides in those novel features of construction. combination and arrangement of parts, all of which will be first fully described in the detailed description and then be particularly pointed out in the appended claims, reference being had to the accompanying drawings, in which: 1

Fig. 1 is a central vertical longitudinal section of my apparatus, the parts being located in the position they assume when the magnet has been energized.

Fig. 2 is a like section with the parts in the normal or inactive position (magnet de-energized).

Fig. 3 is a section on the line 3-3 of Fig. 1.

Fig. 4 is a section on the line 44 of Fig. 1.

Fig. 5 is a plan view of the lower casting having the valve seat.

Fig. 6 is a top plan view of the apparatus.

Fig. '7 is a top plan view of the core.

Fig. 8 is a side elevation of the combined core and valve unit.

Fig. 9 is a magnified detail section showing how the non-magnetic guide 'sleeve is secured fluid-tight to the top of the casing.

Fig. 10 is a side elevation of a hydraulic brakeapplying cylinder (Lockheed type) with my apparatus applied.

Fig. 11 is an elevation of the distributor.

In the drawings, in which like numerals of reference designate like parts in all the figures, i represents the usual brake-applying cylinder and oil reservoir, 2 the brake-applying rod which is operated by the usual pedal and return spring (not shown), 4 the filler cap and 5 the mounting lugs, all of which are of known construction and per se are not of my invention.

My invention comprises a lower cylinder 6 having a diametricai bore 20 recessed at the ends as at 18 and I9 and providing for the screw bolt 3. The cylindrical neck 23 of the bolt fits in recess l8 against a suitable washer 2i (copper, for instance).- The bolt passes through the dis-- tributor 25 (which may be turned on the bolt with its cylindrical neck 26 held in recess l9 against a washer 22) into the brake-applying cylinder I. When the bolt is tight, distributor 25 is held immovable.

The cylinder 6 has a recess 1 in its upper end the wall of which is threaded to screw on the threaded ring 56 of the magnet case 4, later again referred to.

The cylinder 8 has a longitudinal passage I0 around the upper end of which is provided an annular portion 8 having cross grooves 9, the portion 8 constituting a core stop if desired.

Located in a groove in the wall of the passage I0 is a split spring-ring ii which holds the spring stop washer or ring l2 against being forced out by the valve-seating spring (coil) 42 which enthe rubber seal 51 is placed in.the ringso (which ,5; threads into Dandaretaini ng ring" is forced,

gages the metallic washer I! continually to urge the flexible and/or elastic (rubber, preferably) valve seat 40 toward the web II.

The web has a bore I with by-pass grooves Ii, into which bore the cylindrical-plug-valve II has a sliding flt and when the met is energized this valve ll engages valve seat, as will later be made clear.

The e I! below the bolt 8 is tapped and .cloud by a screw plug [1.

The bolt fiias a threaded end I to screw into the cylinder l.

The distributor 25 has a circular groove 21, a threaded socket ll and a duct 2! connecting groove TI to socket 28, while cylinder 0 has a duct lll leading from groove 21 to recess I.

The cylindrical plug valve ii is formed on one end or a stem 32 which is threaded at 34 into the reduced end I! of the core 36 and is formed with a stop shoulder 33. The core, of course, is formed of magnetic material, preferably mild steel, and

outer die-cast shell 44 and aninner pressed steel shell or liner ll having flanges I} and "respectively with matched screw holes for the screws II that secure the cover ll in place. A suitable washer ll. sets in a groove in the outer shell 44, against which washer I! the upper end of cylinder is screwed tightly.

Thecover a has an'annular recess or groove II and a cylindrical lugon which-a thin-brass or other non-magnetic sleeve' 52 i'sjorced'tightly and held to the lug by means of a isshrunkonandliesinrecessli. As best shown in F18; 9, the lug is forthe depth of the groove ii is of slightly greater outside diameter than that of the inner diameter of the sleeve 52, while the lower part of the lug' flts within the sleeve I! with a freeslidingflt. Thus;

when sleeve I2 is forced overthe larger part of ll it will be slightly exp'anded.- .Then' the ring a is heated to expand it'and it is placed over sleeve 52 and into groove IL Oncooling', ring I tightly around 51.; This makes Ii-flllidtight Joint and rigidly secures sleeve 52 to cover It moves The coil it o'i'the magnetis wound I, after which the cover is-screwed on. Then in to hold seal in place.

tapered as at 59 so that the fluid in. recess I under pressure holds the seal "tight around sleeve 52, thus completely isolating the windings Theusualpipe line 0 8 from-cylinder l to the- --wheel brakes (not shown) isdisconnected from.

It (see 10).

"- 8 I h h.

a imit and placed in the casell-Ai and its ends Ii areathreadedtliroughrubber insulating plugs Operation Assume the brakes to be oh; the parts of the attachment will be in the position shown in Fig. 2. Now when the brake rod 2 is forced in (by pressure on the brake pedal, not shown, which is connected to rod 2) the liquid in the system will flow from cylinder I via passage 62 in bolt 3 into the-lower part of passage it; from here it will flow over valve 3| through web opening [4, through valve holes ll into the upper part of passage II, thence through grooves I to recess I and out via ducts 3|, II, to pipe 63 and brakeshoe-applying cylinders (not shown) to set the brakes.

The operator then closes the electric circuit (not shown) which energizes coil Ii, which thereupon draws up to core I and raises valve ll into passage i4 until the core top engagw the bottom-o1 the lug 58, at which time II will engage valve seat 40. Valve seat ll is lightly held down by spring 42 and thus covers grooves ll against back flow of fluid. The circuit remaining closed, when the operator releases pressure on the brake pedal, pressure in the lower chamber (below web it) is reduced, while pressure in the chamber above web ll will remain, since valve seat ll) then acts in cooperation with valve ii to prevent return flow of fluid.

If a partial application of the brakes has been made and magnet coil {-5 remains energized, a further pressure on the brake pedal will cause Ifluid to pass upwardly through by-pass grooves l5, lifting valve seat 40 and flowing through holes II to give the additional pressure required further to apply the brakes. v

To release the applied brakes, with foot 03 the brake pedal, the operator only has to open the coil's circuit again, whereupon the electro-magfrom the position of Fig. l (energized) to that ofFig. 2 (dc-energized). While the spring 42 continuously tends to keep valve seat ll seated (Figs. 1 and 2).'the openings ll allow the return flow of liquid and the consequent release of the' brakes.

It should be understood that the spring 42 is preferably a very light spring of only sufilcient force to overcome any friction between valve seat II and the wall of the chamber or passage in which the seat 40 is located. In fact, the spring 42 may be omitted without rendering the device 'intiperative as the back pressure will ordinarily '-'be sufliclent to bring member 40 against web II when the brake pedal is released. The presence -of the spring 41, however, renders the action of locking the brakes smoother and without lost motion;

'Itsh ould further be noted that the member 4| does not.merely act as a seat with which the upper face of valve 3| engages but also, in cooperation with valve II (which then acts as a seat for member ll). serves as a check valve against re- -turnflowoifluidwhilemagnetiiisenergized -"Betwee'n.ring-5 |'and sleeve 52 the-seal-ilis Furthermore, since member ll is flexible, elas- -tic or 'yieldable, it allows for slight irregularities in machining or assembling the parts I8 and Ii .Ito 36. if when the upper face of valve II is brought into contact with seat 40 before contact occurs between core It and lug 53, (to eliminate'any air-gap in themagnetic circuit) seat the cylinder-TI to'the distributor; w 1 I v I ll will yield enough for contact to be made hemiliar, it has been vitally necessary to see time no pressure is being applied application of thebrakes.

By virtuejotthejconstruction herein described and shown in the'a'ccompanying drawings, I am ableto accomplishjthe desired results (even though the pressure in the brake linesand valves should-as it often does-reach coo pounds per' square lnhifwith a magnet thatuses only about 2 to 2 amperes at 6to 8 volts. Furthermore the construction insures that the valve will be proper- 1y seated and'held seatedby maximum magnetic pull since no air-gap will be present 'at the end oi. the core" becausefthe yielding oi the valve seat permits the core to always engage the cover.

Prior to the invention set forth in my application, aforesaid, in all hydraulic brake systems nowon the market with which I am titsat no airshall be allowed to become trapped in the oil lines and operating cylinder, but with my .invention I am enabled to provide an air cushion for the incompressible motive fluid; by virtue 01' this air cushion a softer application of the brakes to avoid wheel-locking can be obtained and danger voi injury to passengers by sudden stops is reduced 'to a minimum.

This air cushion is caused by the air trapped in the core ducts I '|38 and sleeve 52.

By making the distributor 25 adjustable on its axis, threaded socket 28 may be made to line up conveniently with the direction of pipe 63 (Fig. l), regardless of its position around said axis, and while I have shown only one duct 30 between ring groove 21 and upper chamber 1, it is obvious that more'than one such duct may be employed if found desirable. If several ducts 30 are used they'can be made oi smaller bores than when only one duct is employed.

From the foregoing description, taken with the accompanying drawings, it is thought that the construction, operation and advantages of the invention will be clear to those skilled in the art and I desire it to be understood that changes in the details of construction to adapt the invention to different hydraulic brake systems may be made within the scope of the invention and the appended claims.

Having fully described my invention what I claim as new and desire to secure by Letters Patent of the United States is:

.. chamber communicating with said pipe lines and the lower chamber communicating with said ,brake. -applying cylinder, a normally open valved -passage between said chambers, a solenoidal ma'gnetj including a case secured to said second mentioned cylinder, an energizing coil in said case, a core floating in said coil, a plug valve having a stem rigidly secured to said core in a position such that when said coil is energized and said core is seated in contact with said case to close the magnetic circuit, said valve will close said passage, and when the coil is not energized the core will drop to open said passage, said passage having a. web with a seat for said valve and having by-pass grooves to permit fluid to pass when the plug valve is in the passage-closing position, and a flexible member for seating on said web and on said plug valve when in its passage-closing position for cooperation with said plug valve to close said by-pass against return flow oifluid while said coil is energizedr I 2. In a hydraulic brake-system, means to hold the applied brakes set, said means including a cylinder having a longitudinal passage closed at one end and divided into an upper and a lower chamber by a web having a cylindrical opening and by-pass openings, a yieldable member held on said web and overlapping in part said cylindrical opening, spring meansmounted in said longitudinal passage and continuously tending to seat said member, said member having an opening of less area than that of said cylindrical opening,'means to conduct brake fluid into said lower chamber, means to deliver the same from said upper chamber, a solenoid magnet mounted on said cylinder and a core cooperating with said magnet, said core projecting into said longitudinal passage, and a cylindrical plug valve carried by said core and having a stem passing through the opening in said yieldable' member 'and in said web, said core and said plug valve being movable as a unit and being constructed so that when said magnet is energized said plug valve will fill the cylindrical opening in said web and engage said yieldable member, said member acting in cooperation with said plug valve and said web as a back check valve.

3. In hydraulic brake apparatus which includes a brake-applying cylinder connected by pipe lines to the brakes proper, operator controlled means to lock the fluid in the lines after application of the brakes, said means comprising a cylinder having a web dividing it into an upper chamber and a lower chamber, the upper chamber communicating with said pipe lines and the lower chamber communicating with said brake-applying cylinder, a normally open valved passage between said chambers, electro-magnetlc means under control of the operator for actuating the valve in said passage to close the same, said electro-magnetic means including a case of magnetic material having a bottom and an annular side wall, a cover for the top of said case, said case having a hole in its bottom, a core-guide sleeve secured to said top and projecting through said hole, an energizing coil in said base, an operating core in said sleeve, and means to seal the case against passage of fluid into the coil chamber, said means to seal including an annular flange on the case surrounding and spaced from said sleeve, and a tapered elastic seal held in the space between said flange and said sleeve with the tapered end directed toward the outer end of the sleeve.

4. In hydraulic brake apparatus which includes a brake-applying cylinder connected by pipe lines to the brakes proper, operator controlled means to lock the fluid in the lines after application of the brakes, said means comprising a cylinder having a web dividing it into an upper chamber and a lower chamber, the upper chamber communicating with said ipe lines and the lower chamber communicating with said brake-applying cylinder, a normally open valved passage between said chambers, electro-magnetic means under control of the operator for actuating the valve in said passage to close the same, said electro-magnetic means including a case having a bottom and an annular side wall, a cover for the top 01 said case, said case having a hole in its bottom, a core-guide sleeve sesaid top and projecting through an ergizing coil in said case, an operatsaid sleeve, and means to seal the men core in case against passage oi fluid her, said means to seal including an annular flange on the case surroundin and spaced from said sleeve, and a tapered elastic seal held in the space between said flange and said sleeve with the tapered end directed toward the outer end oi the sleev said cover having a lug surrounded by a groove, said sleeve fltting said lug with retaining triction and a ring in said groove .shrunk over said sleeve around said lug.

lng'cylinder, a normally open valved passage between said chambers. electro-magnetic means under control 01' the operator for actuating the valve in said passage to close the same, said electro-magnetic means including a case 01 magnetic material having a bottom and an annular side wall, a cover for the top of said case, said case having a hole in its bottom, a core-guide sleeve secured to said top and projecting through said hole, an energizing coil in said case, an operating core in said sleeve, means to seal the case against passage of fluid into the coil chamber, said means to seal including an annular flange on the case surrounding and spaced from said sleeve, and a tapered elastic seal-held in the space between said flange and said sleeve with the tapered end directed toward the outer end oi the sleeve, said case comprising an outer cast iron shell and an inner steel liner-tor said shell.

6. In hydraulic brake apparatus which includes a brake applying cylinder connected by pipe lines to the brake proper, operator controlled means to lock the fluid in the lines after application of the brakes, said means comprising a cylinder having a web dividing it into an upper chamber and a lower chamber. the upper chamber communicating with said pipe lines and the lower chamber communicating with said brake-applying cylinder, a normally open valved passage between said chambers, electro-magnetie means under control 0! the operator for actuating the valve in said passage to close the same, said electro-magnetic means including a case having a bottom and an annular side wall, a cover for the top of said case, said case having a hole in its bottom, a core- 'guide sleeve secured to said top and projecting through said hole, an energizing coil on said case, an operating core in said sleeve, and means to seal the case against passage of fluid into the coil chamber, said means to seal including an 's'aid groove shrunk over said sleeve around said 1 lug, said case comprising an outer cast iron shell 1 and an inner steel liner for said shell.

7. In hydraulic brake apparatus which infi-cludes a brake-applying cylinder connected by pipe lines to the brakes pr p l, operator coninto the coil cham-.

,trolled means to m the fluid m the lines after application of the brakes, said means comprising a cylinder having a web dividing it into an upper chamber and a lower chamber, the upper chamber g with said pipe lines and the lower chamber communicating with said brake-applying cylinder. anormally open valved passage between said chambers, electro-magnetic means under control oi the operator for actuatingthevalveinsaid passagetoclosethesame, said electro-magnetic means including a case having a bottom and an annular side wall, a cover ior'the top of said case, said case having a hole in its bottom, a core-guide sleeve secured to said top and projecting through said hole, an energizing coil on said case, an operating core insaidsleeve,meanstosealthecaseagainst passage of fluid into the coil chamber, said means tosealincludinganannularflangeonthecase surrounding and spaced from said sleeve, and a tapered elastic seal held in the space between said flange and said sleeve with the tapered end directed toward the outer end 0! the sleeve, said casecomprising two shells in contact, one shell.

at least, being a die casting and one shell, at least, being of magnetic material.

8. In apparatus of the class described, a cylinder having a longitudinal passage with an apertured web dividing the passage into a lower chamber and an upper chamber, an electromagnetically controlled valve operating in said passage in cooperation with said web to govern the flow oi. liquid through said passage, means to admit liquid into said lower chamber and deliver liquid from said upper chamber, said means including a distributor having a bolt hole, a neck with an annular groove and a discharge duct leading from said groove to the outside of said distributor, said cylinder having a bolt hole intersecting the lower chamber, a bolt passing through said bolt holes, said bolt having a head, means to seal said head to said cylinder and means to seal said distributor to said cylinder when said bolt is screwed into a supporting body, said distributor being rotatably adjustable on said bolt,

said bolt having a duct to deliver liquid into said lower chamber, said cylinder having a duct from said upper chamber to said distributor.

9. In apparatus 0! the clam described, a cylinder having a longitudinal e with an apertured web dividing the passage into a lower chamber and an upper chamber, an electromagnetically controlled valve operating in said passage in cooperation with said web to govern the flow oi liquid through said passage, means to admit liquid into said lower chamber and deliver liquid trom said upper chamber, said means including a distributor having a bolt hole, a neck with an annular groove and a discharge duct leading from said groove to the outside of said, M

distributor, said cylinder having a bolt hole intersecting the lower chamber, a bolt passing through said bolt holes, said bolt having a head, means to seal said head to I said cylinder and means to seal said distributor to said cylinder when said bolt is screwed into a supporting body, said distributor being rotatably adjustable on said bolt, said bolt having a duct to deliver liquid into said lower chamber, said cylinder having a duct from said upper chamber to said distributor, said bolt having an annular collar and said cylinder having recesses one to receive said collar and one to receive said distributor's neck.

10. In a hydraulic brake system, means to hold the applied brakes set, said means includ- I a lower chamber by a web having a main opening cylinder having a longitudinal 'ir'ag, spring means mounted in and by-pass openings, a disc valve seat held on said web and overlapping in part said main opensaid longitudinal passage and continuously tending to seat said valve seat on said web,'said valve having an-opening of less area than that of said web opening, means to conduct brake fluid into said lower chamber, means to deliver the same from said upper chamber, a solenoidal magnet mounted on said cylinder and a core cooperating with said magnet, said core projecting into saidlongitudinal passage, and a plug valve shaped to flt in said opening andcarried by said core and having a stempassing through the opening in said disc valve seat and in said web, said core and said plug v'aive being movable as a unit and being constructed so that when said magnet is energized said plug'valve will flll the main opening in said web and engage said disc valve seat, said disc valve seat acting in cooperation with said plug valve as a back check valve when the magnet is energized.

11. In a hydraulic brake system, means to hold the applied brakes set, said means including a passage closed at one end and divided into an upper and a lower chamber by a web having a main opening and by-pass openings, means to conduct brake fluid into said lower chamber, means to deliver brake fluid from said upper. chamber, a flexible disc having a fluid passage and being held yieldably on said web and overlapping in part said main opening, a solenoid magnet mounted on said cylinder, and a core cooperating with said magnet and projecting into said longitudinal passage and provided with a valve to flt within said main opening as a closure therefor, said core and valve being movable as a unit, said disc being constructed to yield sufllciently when contacted by said plug valve to allow said core to be fully seated before the return load of the brake fluid begins to function.

12. Ina hydraulic brake system, means to hold the applied brakes set, said means including a cylinder having a passage closed at one end and divided into an upper chamber. and a lower chamber by a partition having a main fluid passage and by-passages, means to introduce brake fluid into the lower chamber'and to conduct the same from said upper chamber, a solenoid magnet including a case and a coil within the case and a cover for the case, a core, said cover being adapted to cooperate with said core in closing the magnetic circuit when said coil is energized, means to energize said coil when desired, a plug valve carried by said core to fit said main fluid passage as a closure for the same when said coil is energized and said core is seated against said cover, a flexible disc having a fluid passage and being located in said upper chamber for resting on said partition and projecting over said bypassages and in part over said plug valve, said disc being adapted to yield sufliciently when engaged by said plug-valve to permit said core to become fully seated to close the magnetic circuit before back pressure occurs in the brake fluid and after said coil has been energized, said disc being free to leave said plug valve and said partition under brake-applying pressure to open communication between said lower and upper chambers via said by-passages.

13. In ahydrauiic brake system, means to hold theapplied brakes set, said means including a cylinder having a longitudinal passage closed at one end and divided into an by-pass openings, means to conduct brake fluid into said lower chamber, means to deliver brake fluid from said upper chamber, a flexible disc having a fluid passage and being held yieldably on said web and overlapping in part said main opening, a solenoid magnet mounted on said cylinder, a core cooperating withsaid magnet and projecting into said longitudinal passage and provided with avalve to flt within said main opening as a closure therefor, said core and valve being movable as a unit, said disc being constructed to yield sufllciently when contacted by said plug valve to allow said core to be fully seated before the return load of the brake fluid begins to function, and an air-spring in communication with said upper chamber and the fluid therein.

14. In hydraulic brake apparatus which includes a brake-applying cylinder connected by pipe lines to the brakes proper, operator controlled means to-lock the fluid in the lines after application of the brakes, said means comprising a cylinder having a web dividing it into an upper chamber and a lower chamber, the upper cham ber communicating with said pipe lines and the lower chamber communicating with said brakeapplying cylinder, a normally open valve passage between said chambers, electro-magnetic means under control of the operator for actuating the valve in said passage to close the same, said electro-magnetic means including a case of magnetic material having a bottom and an annular side wall, a cover for the top of said case, said case having a hole in its bottom, a core-guide sleeve secured to said top and projecting through said hole, an energizing coil in said case, an opercally-controlled means for preventing return flow of fluid under pressure from the motor to the source after said motor has been actuated by fluid under pressure from the source, said means comprising a member having a passage forming part of the conduit means and provided with an annular ledge, an annular valve seat of yieldable material cooperating with the ledge and extending into a part of the passage, a valve element for engaging with the extended portion of the valve seat to thereby close the passage, said valve element engaging the valve seat by a movement in the direction of flow of fluid to the motor, and solenoid means for actuating the valve element to a seated position and holding it seated.

16. In fluid pressure actuating apparatus provided with a source of pressure, an actuating motor and conduit means therebetween, electriupper and a lower chamber by a web having a main. opening and cally-controlled means for preventing return flow part of the conduit means and provided with an annular ledge, an annular valve seat 0! yieldable material cooperating with the ledge and extending into a part or the passage. a valve element ment to a seated position and holding it seated,

said solenoid means comprising a core and a stop therefor 01 magnetic material and said seat yieldingtopermitthecoretoengagethestop when the solenoid is energized in the event the valve element engages the seat prior to the core eng in the stop.

17. In fluid pressure actuating apparatus provided with a source of pressure, an actuating motor and conduit means therebetween, electrically-controlled means for preventing flow oi fluid under pressure from the motor to the source after said motor has been actuated by fluid under pressure from the source, said means comprising a valve seat associated with the .conduit means, a valve element forengaging said seat by a movement in the direction or flow oi fluid from the source to the motor, a solenoid for moving said valve element against the seat and including a core connected to the valve element, an energizing coil, and a member 01' magnetic material in the magnetic circuit engageable by the core when said core is moved to seat the valve as a result of the coil being energized, and means permitting the core to have additional movement against a yieldable resistance after the. valve element engages the seat to thus insure that the core will engage the member when the coil is energized.

18. In fluid pressure actuating apparatus provided with a source of pressure, an actuating motor and conduit means therebetween, electrically-controlled means for preventing flow oi fluid under pressure from the motor to the source after said motor has been actuated by fluid under pressure from the source, said means comprising a valve seat associated with the conduit means, a valve element for engaging said seat by a movement in the direction of flow oi fluid from the source to the motor, a solenoid ior moving said valve element against the seat and including a core connected to the valve element, an energizing coil, and a member of magnetic material in the magnetic circuit engageable by the core when said core is moved to seat the valve as a resultoi' the coil being energized, and means insuring that the core will be in engagement with the member and the valve element will be in pressure engagement with the seat when the coil is energized.

19. In fluid pressure actuating apparatus provided with a source of pressure, an actuating motor and conduit means therebetween, electrically-controlled means for preventing return flow of fluid under pressure from the motor to the 'said motor has been actuated by source after saidmotorhas been actuated byfluid under pressure from the source, said means comprising a passage having associated therewith a valve seat capable oi yielding in the direction of now or fluid to the motor, a valve element for engaging the seat by a movement in the direction of yield of said seat, and means for moving said valve into engagement with the seat comprising a solenoid including a core element connected to the valve element, an energizing coil, and stop means for said core including a member of magnetic material Positioned in the magnetic fleld, said yieldable seat when engaged by the valve element as a result oi energization of the coil permitting additional movement of said element so as to insure that the core will engagethestop. I

20. In fluid pressure actuating apparatus provided with a source of pressure, an actuating motor and conduit means therebetween, a valve seat of yieldable'material associated with the conduit and haing a passage therethrough, a

valve element for engaging the valve seat by a movement in the direction of flow of fluid through the passage and toward the motor, and means for moving said,,valve element onto the seat to close the passage, said valve seat being yieldable to permitadditional fluid to be forced thereto to the motor notwithstanding the valve element is in a position closing the passage against return flow oi fluid irom the motor.

21. In fluid pressure actuating apparatus provided with a source 01' pressure, an actuating motor and conduit means therebetween, electricallycontrolled means for preventing flow oi fluid under pressure from the motor to the source alter fluid under pressure from said source, said means comprising a valve seat associated with the conduit means and capable of having yieldable movement in the direction of flow of fluid toward the motor, a valve element for engaging said seat by a movement in the direction of its yield, and solenoid means for seating the valve element and holding it seated when energized.

22. In fluid pressure actuating apparatus provided with a source of pressure, an actuating motor and conduit means therebetween, electrically controlled means for preventing flow o1 fluid under pressure from the motor to the source after said motor has been actuated by fluid under pressure from said source, said means comprising a valve seat associated with the conduit means and capable of having yieldable movement in the direction of flow oi fluid toward the motor, a valve element ior engaging said seat by a movement in the direction of its yield, solenoid means for seating the valve element and holding it seated when energized, and means includingsaid yieldable valve seat for permitting additional fluid under pressure to be forced to the motor from the source when the valve means is in closed position to prevent flow oi fluid back to the source.

FRANK L. DARLING.

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