US2378409A - Hydraulic elevating mechanism - Google Patents

Description

June 19, 1945. J. F. JOY

HYDRAULIC ELEVATING MECHANISM Filed March 18, 1942 2 Sheets-Sheet l Pi -li- 1111621311 F1 LIny 9% fl Ww LZ/QAMZ June 19, 1945. J. F. JOY 2,378,409

HYDRAULI C ELEVAT ING MECHANI SM Filed March 18, 1942 2 Sheets-Sheet 2 gwucwto'n 110 551311 E LIE] Patented June 19, 1945 UNITED STATES PATENT OFFICE (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 4 Claims.

making it readily adaptable to field requirements.

It is a further object to provide a mechanism which may be operated with greater ease and convenience than prior mechanisms.

I It is another object to provide an elevating mechanism in which inaccuracie due to backlash and play in the gear trains will have been eliminated and in which such inaccuracy will not appear due to wear in the equipment incidental to use thereof.

Additional objects include the provision of an elevating mechanism in which all moving parts are inclosed and operate in a bath of oil and one in which the holding strains incident to firing and recoil of the gun may be relieved through the use of valves set to Operate at a predetermined pressure without transmitting such strains to the other hydraulic equipment and with considerably less shock to the carriage proper.

The exact nature of the invention as well as other objects and advantages thereof will appear from a description of a preferred embodiment as shown in th accompanying drawings in which. I

Figure 1 is a diagrammatic side elevational view of the elevating mechanism in association with a gun carriage.

Figure 2 is a vertical longitudinal sectional view of the elevating cylinder.

Figure 3 is a horizontal, longitudinal sectional view of a portion of the piston taken on the line 3-3 of Figure 2.

Figure 4 is a horizontal, longitudinal sectional view on the line 4-4 of Figure 2.

Figure 5 is a longitudinal sectional view of one of the stop valves for the elevating cylinder.

Figure 6 is a longitudinal sectional view through a portion of the carriage and the stop valve operating mechanism.

Figure 7 is an end elevational view of the stop valve operating mechanism.

Figure 8 is a longitudinal sectional view of the operating handwheel, and

Figure 9 is an end elevational view of the operating handwheel with parts broken away to show the inner construction.

Referring to the drawings by characters of reference there is shown in Figure 1 a'portion of the top carriage I of an artillery weapon comprising a barrel carrying cradle 2 trunnioned on the top carriage at 3. An arm 4 depends from the cradle and to this arm is secured the end 5 of a piston rod 8 reciprocable in the elevating cylinder 1. A reversible hand operated pump 8 may be mounted on the carriage at any location convenient to the gunner's station or a unidirectional pump provided with a suitable reversing valve may be an alternative. From the pump 8 fluid lines 9 and ID of flexible tubing lead to similar stop valves II on opposite ends of the elevating cylinder 1 through which the fluid may be admitted to or withdrawn from the elevating cylinder to act on opposite faces of the piston l 3 slidable therein. It is the function of the stop valves to close the ends of the cylinder and lock the gun in any desired position, at the same time serving to protect the pump and tubing from extreme pressure which may result on firing. In effecting these purposes the stop valves are controlled by means of flexible cables l4 and I5 slidable through flexible jackets and operated in conjunction'by a treadle IE or other manually or pedally actuated operating means.

Referring in detail to the various components, the elevating cylinder 1, shown in Figures 2 to 4, comprises the piston rod 6 which extends from both ends of the cylinder, the piston l3 within the cylinder and the inclosing cylinder heads l1 and I8. Both of the cylinder heads are equipped with suitable packing glands l9 to permit the piston rod to reciprocate without allowing fluid leakage. It will be noted that the piston rod is thus supported at both ends of the cylinder as well as by the piston insuring maximum stability of alignment at any piston position. The cylinder head I l nearest the end 5 0! the piston rod is provided with a plurality of spaced fluid inlet ports 20. The plurality of ports are provided in order that one may come to rest in a position that will permit of the convenient attachment of the necessary oil conduits and accessories, since the final position a single nort might take when the cylinder head is screwed into a seat on th end of the cylinder cannot conveniently be predetermined. The plurality of ports are also useful in allowing for the bleeding of air which might otherwise be trapped in the cylinder during the filling operation. Those ports not in use may be closed with common pipe plugs which will preferably be well tinned to insure sealing. The opposite cylinder head I8 is provided with a pair of opposed cup-like members 2I adapted to be trunnioned on the top carriage and with a pair of fluid ports 22 t the bottom one of which is connected the fluid conduit and accessories, while the top port is used to bleed air during filling of the system and later sealed off with a plug.

Although during the firing and recoil cycles the pressures in the cylinder may reach extreme limits, the normal load during gun elevation approximates a pressure of about 30 pounds to the square inch. It will be seen, therefore, that the matter g of packing friction during the period of high pressure is relatively unimportant, and it has been found that the use of ordinary fluid pressure responsive oil packing of chevron cross section serves to provide adequate sealin for the piston I3 as well as for the packing glands at the ends of the cylinder. Further, this type of packing does not require the high degree of cylinder wall finish which must accompany the use of the silver ring and similar packings commonly employed in recoil mechanisms and the like. The piston comprises the body I3, opposed rings 23 of chevron type packing, and a clamping ring 24 held in engagement with the packing by shoulders on the jointed piston rod 6. The piston is further provided with a pair of relief valves 25. As shown in Figure 3 each relief valve comprises a passage 26 communicating with an end face of the piston. A ball valve 2'! is seated on the inner end of the passage 26 and retained thereon by means of a spring follower 28, a spring 29 and a spring retainer 30. Diverging from the inner end of the passage 26 are a pair of outlet passages 3| communicating with the opposite face of the piston. The other of the relief valves is of similar construction but has its corresponding port 26 and ports 3| communicating with the opposite faces of the piston as best shown in Figure 2. The springs on these valves are compressed, to an extent sufficient to allow either valve to open only when the pressure tending to open that valve exceeds about 5000 lbs. per square inch. The function of these valves is to permit the piston in the elevating cylinder to yield under the extreme forces which may be encountered in firing and thus to absorb these forces to some extent in throttling at the relief valves thereby preventing the transmission of unusual forces into the carriage and mount.

Similar stop valves l I shown in detail in Figure 5 are provided in the ports in the ends of the elevating cylinder. Each stop valve comprises the body II having a threaded male portion 32 adapted to engage the cylinder port and a poppet valve 33 inside the body and loaded with the spring 34 constraining the valve to a seat 35 in which position flow of fluid from the cylinder will be prevented. An operating stem 36 extends from the body'of the valve through packing 31 to be engaged by the valve operating mechanism. Threaded means 38 are provided on the body to engage the flexible fluid conduit and a bracket 39 is provided to support the valve operating control cable H. The primary function of the stop valves is to lock the gun in fixed position at any desired elevation, but they have the additional function of preventing the abnormal pressures which may arise within the elevating cylinder,

during firing and recoil, from escaping into the exterior oil circuits to the pump where such pressures might cause damage to the equipment or injury to the operator.

The stop valve operating mechanism shown in detail in Figures 6 and '7 comprises a pair of spring loaded flexible push rods I4 and I5 each provided with a sleeve 46 adapted to secure the casing of the rod to a portion of the top carriage I while the other ends of the push rod casing are secured to the brackets 39 on the stop valves II. A foot treadle I6 is swingably mounted on the top carriage I and has a pair of depending arms H in alignment with the ends of the push rods I4 and I5 as shown in Figures 5 and 6. It will be seen that depression of the treadle will open both valves simultaneously and, because of the spring loading of valves and push rods, the valves will automatically close and lock the n in position when pressure is released from the treadle.

A further advantage is that after release of the stop valves further operation of the pump may force additional fluid past the spring closed valve in the event that there is any void in the system insuring that there will be no slack in holding the gun at the desired elevation.

Although the pump 8 shown in the drawings is of the directly reversible type it will be obvious that any fluid pressure and valve combination capable of selectively applying pressure to one or the other of the fluid lines 9 and I0 may be used. Such an alternative might be a unidirectional pump provided with a reversing valve by which the fluid lines 9 and I0 might be interchanged in their relation to the pump.

In order to insure that there will always be an adequate supply of fluid in the system it is contemplated that a reserve supply of fluid be provided in a chamber mounted on the pump or in any other convenient location. This chamber is preferably provided with check valves which permit fluid to flow to the intake side of the pump but prevent any reverse flow to the chamber. As further insurance against air voids the system is preferably closed and maintained under approximately 50 pounds per square inch of pressure which may be conveniently applied by the application of pneumatic pressure to the reserve fluid in the chamber 80.

While the oil pump 8 may be operated to elevate or depress the gun by means of a plain handwheel or crank, it is considered desirable to provide a handwheel which has provision for direct drive and also embodies a reduction gear mechanism for more precise movement of the gun in final setting. Accordingly the handwheel shown in Figures 8 and 9 has been provided. This handwheel assembly comprises a fixed gear wheel 83 secured to the end plate SI of the pump body in concentric relation to the pump shaft 59 and having gear teeth 84 on the periphery thereof. The handwheel 85 is secured on the shaft 59 and is generally parallel to the fixed wheel 83 and has a skirt 86 inclosing the fixed wheel and an annular guard plate 81 secured to the skirt thus completing the inclosure of the toothed P01151011 of the gear. The handwheel 85 is provided with an axially bored grip 88 and within the axial bore a secondary crankshaft 89 is arranged to be rotated by an auxiliary crank 90. The secondary crankshaft 89 carries on its inner portion a pinion BI adapted to engage the teeth 84 on the periphery of the fixed gear. Space is provided in the grip 88 to allow the secondary shaft to be reciprocated sufiiciently -to engage or disengage the pinion. Circumferential grooves 92 on the secondary shaft and a cooperating spring pressed plunger 93 form convenient means for releasably retaining the secondary shaft in either desired position. The employment of such an auxiliary crank on the handwheel greatly reduces the effort needed to move the gun in spotting it on the target thus permitting more precise settings while the provision of a direct drive permits rapid elevation or depression of the gun through wide changes of elevation which may be necessary in changing from one target to another- I claim:

1. In a hydraulic mechanism for elevating a gun adapted to be fixed to a gun carriage, a hydraulic cylinder adapted to be rockably mounted on the carriage, a piston in said cylinder adapted to be attached to a gun cradle, a fluid supply, a fluid pump adjacent the carriage for supplying fluid to said cylinder, a casing at each end of the cylinder and provided with a fluid passage therethrough communicating at one end with the cylinder, fluid conduits leading from the pump and communicating with said casing passages, a stop valve in each casing for controlling the passage of fluid through the casing, spring means holding said valves normally closed to obstruct the flow of fluid from the cylinders, manually operable means for simultaneously opening and holding said valves open during the operation of the pump to permit fluid to enter either end of the cylinder selectively, said means being releasable to permit the valves to simultaneously close to trap the fluid on both sides of the piston.

2. In a hydraulic mechanism for elevating a gun, adapted to be fixed to a. gun carriage, a hydraulic cylinder adapted to be rockably mounted on the gun carriage, a piston in said cylinder adapted to be attached to a gun cradle, a fluid pump adjacent the carriage for supplying fluid to said cylinder, a casing secured to each end of the cylinder and provided with fluid passages therethrough communicating at one end with said cylinder, fluid conduits leading from the pump and connecting with the casing passages, a stop valve in each casing for controlling the passage of fluid through said casing, springs normally holding said valves closed to obstruct the flow of oil from said cylinders, a push rod in each casing operable to open the valve against the influence of said springs, manually operable means remote from the cylinder to actuate the push rods to simultaneously open the valves and hold them open during the operation of the pump to permit fluid to enter either end of the cylinder selectively, said means being releasable to surrender the valves to their springs to simultaneously close the valves to trap the fluid on both sides of the piston.

3. The invention of claim 1 characterized in that the manually operable means for opening the stop valve comprises a treadle adapted for attachment to the carriage and having portions for engagement with the push rods to project them to position to open the valves when the treadle is depressed, and means for returning the push rods and treadle to normal position.

4. The invention of claim 1 characterized in that the piston is provided with passages extending from face to face thereof, a valve seat in each passage on opposite faces of the piston, a springbacked valve in each passage, said springs being tensioned to a degree suflicient to allow the valves to open only when the piston is subjected to excessive pressures that may be encountered in the normal operation of the gun.

JOSEPH F. JOY.

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