US2959923A

US2959923A - Material handling apparatus

Info

Publication number: US2959923A
Authority: US
Inventors: William M Shook
Original assignee: Warner and Swasey Co
Current assignee: Warner and Swasey Co
Priority date: 1958-03-27
Filing date: 1958-03-27
Publication date: 1960-11-15
Anticipated expiration: 1977-11-15
Also published as: DE1409673A1; GB846241A

Description

Nov. 15, 1960 w. M. SHOOK 2,959,923

MATERIAL HANDLING APPARATUS Filed March 27, 1958 4 Sheets-Sheet 1 5 I20 //5 K m //9 F A m v "3 fills /24 A 72 swme VALVE V g INVENTOR. WILLIAM M- SHOCK 31%; 1 I )6 6 flM M ATTORNEYS Nova 15, 1960 w. M. SHOOK 2,959,923

' MATERIAL HANDLING APPARATUS Filed March 27, 1958 4 Sheets-Sheet 2 INVENTOR. WILL/AM M. SHOO/r A TTORNE Y5 Nov. 15, 1960 w, M. SHOOK MATERIAL HANDLING APPARATUS IN V EN TOR.

m MM ME M Ww Nov; 15, 1960 Filed March 27, 1958 E D I m W. M. SHOCK MATERIAL HANDLING APPARATUS 4 Sheets-Sheet 4 G 9 LOW TORQUE- HIGH SPEED-MOTORS IN ,SERIES HIGH TORQUE-LOW SPEED-MOTORS //V PARALLEL IN VEN TOR. W/L L IAM M. 5H00/1 I AT T0 R/vEYs United States Patent ice 2,959,923 MATERIAL HANDLING APPARATUS William M. Shook, New Philadelphia, Ohio, assignor to The Warner & Swasey Company, Cleveland, Ohio, a corporation of Ohio Filed Mar. 27, 1958, Ser. No. 724,365 12 Claims. (CI. 60-97) The present invention relates to material handling apparatus and more particularly to apparatus for moving earth and other materials.

An object of the present invention is to provide m1- proved means for automatically shifting at least two fluid receiving means, and more particularly, two fluid motors, operating in series to a parallel operating arrangement.

Another object of the present invention is to provide improved means for automatically shifting at least two fluid motors from a low torque, high speed operating arrangemenit to a high torque, low speed operating arrangement by simply increasing the load upon the driven shafts of the motors. 7

Another object of the present invention is to provide a new and novel automatic multispeed mechanism for rotating a turntable which carries a heavy load moving apparatus.

Another object of the present invention is to provide a turntable capable of being automatically rotated at a greater speed when unloaded than when loaded or when the load exceeds a predetermined amount.

Another object of the present invention is to provide a fluid motor drive system, for a rotatable turntable having a material handling apparatus mounted thereupon, comprising a pair of fluid motors operable in series or parallel, depending on the characteristics of the load carried by the material handling apparatus.

Another object of the present invention is the provision of improved means for automatically rotating a turntable supported material handling tool at a greater speed when the tool is not carrying a load than when the tool is loaded whereby upon depositing the material the tool is swung back to its pickup point at a higher speed. This not only increases the operating efficiency of the machine, but increases the capacity of the machine as well.

Another object of the present invention is to provide a fluid operated turntable mechanism provided with auto- 1 matic means for braking and/ or locking the turntable in place upon deenergizing the turntable mechanism and automatically freeing the turntable for rotation upon energizing the turntable mechanism.

Another object of the present invention is to provide a driving apparatus for a turntable having a material handling apparatus mounted thereupon, which driving apparatus is automatically stopped should an overload thereof or obstruction to the rotation of the turntable occur.

Another object of the present inventionis to provide a means for driving a turntable having a material handling apparatus mounted thereupon through substantially 360" in either direction from any point on the turntable.

This invention further resides in certain novel features of construction, and combinations and arrangements of parts, and further objects and advantages thereof will be apparent to those skilled'in the art to which it pertains from the following description of the presentpreferred embodimentthereof described with reference to the accompanying drawings in'which similar reference charac- 2,959,923 Patented Nov. 15, 1960 ters represent corresponding parts throughout the several views, and in which:

Fig. 1 illustrates a preferred application of the present invention and more particularly shows a vehicle with a turntable which mounts a telescoping boom with an earth moving tool secured to the outer. end thereof;

Fig. 2 is a diagram of a preferred embodiment of the control system for the fluid motors of the present invention; I

Fig. 3 is a top plan view of the drive mechanism for the turntable and tool shown in Fig. 1;

Fig. 4 is a fragmentary sectional and side view of ;a brake mechanism connected to a housing of the turntable drive mechanism which mechanism is also shown in sectional view through the center axes of two shafts therein for showing the brake and gearing arrangement;

Fig. 5 is an elevational end view of the swing or rotation control valve shown in Fig. 2;

Fig. 6 is a partial cross-sectional View of the swing or rotation control valve along line 6-6 of Fig. 5

Fig. 7 is a cross-sectional view along line 7-.-7 in Fig. 6, but with a spool valve fully assembled in and forming a part of the control valve;

Fig. 8 is a schematic sectional view, of the control valve showing the position of the spool valves and the fluid path through the swing or rotation control valveto the fluid motors when the fluid motors arebeing operated in series;

Fig.9 is a view sirnilar'to Fig. 8 with the exception that the fluid motors are being operated in parallel; and

Fig. 10 shows a modification of the present invention.

Before explaining in detail a preferred embodiment of the present invention it isv to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated inthe accompanying drawings, since the invention is capable of otherembodiments and of being practiced. or carried out in various ways. It is'to beunderstoodgalso that the phraseology or terminology employed herein is for the purpose of description not of limitatiomand-it is'not intended to limit the invention herein claimed beyond the requirements of the prior art. a

In Fig. l of thepresent invention, reference numeral 10 14 provided with the usual operators controls for driving the vehicle, is mounted over a motor 15 in a conventional manner at the front end of the chassis 11.

Telescoping inner and outer booms 16 and-17, respectively, are pivotally mounted upon a turntable 18 rotatably mounted upon support 19whichis rigidly secured to chassis 11. A boom operators cab 20 is mounted upon turntable 18 to one side of telescopicboom 16 and 17 with a power unit 21 mounted immediately to. the rear of the cab 20. A material handling tool, and more particularly an earth moving shovel 22, is pivotally secured to the outer end of outer boom 17.

Drive mechanism dition of the turntable is essentially proportionalto the f torque load on the pinion 30. The control mechanism. for the motors A, B will be fully described hereinafter. The pinion gear 30 is in driving engagement with an in;-v ternally toothed annulus or bull wheel, not shown,

mounted in the housing of turntable 18. Pinion is mounted upon a vertical shaft 31. Pinion shaft 31 is journalled in a conventional roller thrust bearing assembly 32 comprising conical roller thrust bearings interposed between inner and outer races. The outer race of the thrust bearing 32 is rigidly secured to a flanged hub 33 which, in turn, is bolted to an integral wall portion of housing 34 which bears upon a horizontal support plate 18 shown schematically, which forms a part of turntable 18. Housing 34 is rigidly secured within the housing of turntable 18 shown in Fig. 1. However, it is understood that the driving arrangement for the turntable 18 can, alternatively, be secured to the chassis 11.

An adjustable locking nut 37 is threaded upon the shaft 31 for the retention thereof and the inner bearing race in assembly and preventing the same from relative axial movement. A flanged retainer ring 38 is secured to flanged hub 33 by conventional means such as screws 39. A pair of conventional packing rings 40 are interposed in sealing relationship between the retainer ring 38 and the pinion shaft 31 in a manner well known to those skilled in the art. Another packing ring 41 has been interposed in sealing relationship between an axially extending end of flanged hub 33 and pinion shaft 31 in juxtaposition with pinion 30. The packing rings 40 and 41 serve to retain lubricant within the flanged hub 33 and retainer ring 38 for the thrust bearing assembly 32.

A large gear wheel 42 is keyed to shaft 31 adjacent an outer end 31 thereof, end 31' having a reduced diameter and being secured within the inner race of a second thrust bearing assembly 43. The outer race of the thrust bearing 43 is tightly fitted within an opening formed in a hub plate 44 secured to housing 34. A cover plate 46 secured to hub plate 44 with screws 47, not only encloses the opening formed in hub plate 44 but also axially abuts the radial end face of the outer race of the hearing assembly 43 for locating the same and controlling the load thereon.

A countershaft 50 having a gear 51 rigidly secured thereto, in mesh with gear wheel 42, is journalled in housing 34 as follows: A cup-shaped journal bearing housing 52 is rigidly secured in an opening formed in the wall of housing 34. A thrust bearing assembly 54 is provided in the cup-shaped journal housing 52 for frictionlessly journalling one end of the countershaft 50 therein. The other end of countershaft 50 is journalled in a flanged hub member 55 secured to a flat cover plate 56 by appropriate means, such as screws 57, the flat plate 56 being secured to housing 34 by means of machine screws 58 and the flanged hub member 55 which frictionlessly supports the countershaft 50 by means of an antifriction thrust bearmg 59 in a conventional manner. The countershaft 50 is provided with an extension 60 for a purpose to be later described and a second gear wheel 61, keyed to countershaft 50 between gear 51 and thrust bearing assembly 54, the gear wheel 61 being in mesh with a pair of driving gears 62 'mounted upon drive shafts 63 of fluid motors A and B. Only fluid motor B is shown in Fig. 4. Each of the fluid motors A and B is mounted and secured to the housing 34 in a conventional manner, such as by nuts 64 and bolts 65, for driving the pinion gear 30 via driving gears 62, a second gear wheel 61, gear 51 and first gear wheel 42, respectively.

Brake The aforementioned shaft extension 60 is provided for supporting a brake arrangement 66 comprised of a spider assembly 67 of integrally connected members 67a, 67b and bearing retaining member 670 mounted about a cylindrical armature 68 and rigidly secured to flanged hub member 55, the armature 68 being slidably keyed to the outer end of shaft extension 60 for limited axial movement for a purpose to be described. A plurality of spaced annular clutch disks 69 have been provided between the armature 68 and the spider 67 and alternately connected to the two members 67, 68 in a well-known manner so that a small inward movement of the armature 68 causes the disks mounted thereupon to engage the disks secured to the spider 67 for braking and locking the turntable 18 against rotation by locking the countershaft 50. A packing ring 70 is disposed between the spider 67 and the extended end.60 of countershaft 50 for providing a seal against leakage of lubricant from the thrust bearing 59 to the clutch disks 69. The brake arrangement 66 comprising a brake cylinder 71 having a piston 72 slidable therein, Figure 2, is mounted upon the cover plate 56. A piston rod 75, connected to the piston 72 within the brake cylinder 71, is provided with an actuating rod 76 having one end threaded into the outer end thereof, the rod 76 at its other end being pivotally secured to a pair of clutch actuating levers 77 of a yoke 78 by means of a pivot pin 79.

The brake cylinder 71 is pivotally secured to a mounting bracket 80 which comprises a base plate 81 secured to cover plate 56 and a pair of parallel, flat support plates 82 spaced on either side of the brake cylinders central axis and disposed perpendicularly thereto. The other ends of the upstanding flat support plates 82 are provided with a transverse cylinder retaining pin 83 secured therein in a conventional manner and passing through a transverse opening 84 formed in an end of cylinder 71 for pivotally securing cylinder 71 thereto. The other ends of support plates 82 are rigidly secured to a transverse wall portion 85 which is not only disposed perpendicularly to the support plates 82, but is also disposed perpendicularly to the base plate 81. Transverse wall portion 85 has a circular opening generally coaxial with the central axis of cylinder 71 and rod 76 for accommodating the passage therethrough of one end of the latter.

A helical spring 86, encircling actuating rod 76, abuts at one end thereof against a spring seat 87, bearing against the wall portion 85 of mounting bracket 80. An adjustable stop for adjusting the tension of spring 86, comprises a spring seat 89, similar to spring seat 87, and a fiat washer hearing against adjustable nut 91 threaded on rod 76. The foregoing arrangement provides a resilient means for normally biasing the piston 72, piston rod 75, and actuating rod 76 into the hydraulic cylinder 71 and engaging the brake 66 in a manner to be described. Wall portion 85 is provided with a lug 92 rigidly secured there to pivotally connected to levers 77 for supporting yoke 78 by means of a pin 93. The yoke 78, comprising an arcuate fork-like portion 94 secured to outer end portions of levers 77, extends on either side of the outer end of armature 68 and pivotally engages a pair of oppositely extending radial rods 95 for engaging and disengaging the brake 66.

Upon supplying pressure fluid to brake cylinder 71 the piston 72 is urged outwardly thereof and brake actuating yoke 77 is urged in a clockwise direction about pin 93 for disengaging the brake 66. Upon relieving the brake cylinder 71 of pressure fluid in a manner to be described, the resilient action of return spring 86 forces the brake actuating yoke 77 in a counterclockwise direction about its pivot pin 93 and the armature 68 is forced inwardly of spider 67 for engaging the brake 66.

Control system The control system for the motors A, B and brake 66. Fig. 2, comprises a motor driven pump 96, which draws fluid from a sump 97 via an intake line 98, and feeds pressure fluid to a control valve 99 by way of a four-way valve 100 for reversing the direction of fluid flow to and from the valve 99. The valve 99 connects the fluid pressure source 96 and sump 97 to the vane-type fluid motors A and B via

lines

101, 102, 103 and 104 so that the motors A, B operate in parallel or in series in the desired direction in a manner to be described for rotating the turntable 18 at high speed in its unloaded condition and at low speed, but at high torque, in its loaded condition. Since the valve 99 controls the swinging or rotative movement of the turntable it will be designated herein as a swing valve.

More particularly, pump 96 supplies pressure fluid to reversing valve 100 over discharge line 106. The reversing valve 100 has four ducts or

lines

108, 109, 110 and 111 which permit the pump 96 to be connected to a port 113 or a port 114 in swing valve 99.

Lines

115 and 116 connect the reversing valve 100 to

ports

113 and 114, respectively. A return line 118 connects the reversing valve 100 to sump 97.

In a first position of reversing valve 100, the pump 96 feeds pressure fluid through

lines

106, 108 and 115, respectively, to port 113 of swing valve 99 and fluid is returned therefrom to sump 97 via port 114 and

lines

116, 111 and 118, respectively. The motors A, B accordingly are driven in a first direction.

In a second position of reversing valve 100, the pump 96 feeds pressure fluid through

lines

106, 109 and 116, respectively, to port 114 for driving motors A, B in a second or reverse direction, the expended fluid being returned to sump 97 via swing valve port 113 and

lines

115, 110 and 118, respectively.

An intake port 119 for the brake cylinder 71 is connected to the line 115 by means of

lines

120 and 121, respectively, the line 121 being provided with a one-way check valve 122 for permitting pressure fluid to be supplied to brake cylinder 71 from line 115 only. A similar arrangement comprising a line 123 having a one-way check valve 124 connects line 116 with line 120 for supplying pressure fluid from line 116 to brake cylinder 71.

An exhaust port- 126 in cylinder 71 permits fluid to be bled therefrom through return line 127 to sump 97. An orifice 128 is interposed in line 127 for controllably restricting the flow of fluid bled from brake cylinder 71 with the result that pressure fluid constantly flows from brake cylinder 71 at a controlled rate when the brake 66 is held in disengaged position.

From the foregoing arrangement it is apparent that the piston 72 in cylinder 71 will be urged outwardly thereof for disengaging brake 66 upon the pump 96 supplying pressure fluid to either of the

lines

115 or 116, the return spring 86 serving to bias the piston 72 into brake cylinder 71 for engaging brake 66 when the pressure in

lines

115 or 116 falls below a predetermined level.

From'the foregoing it is also apparent that fluid can be supplied to the swing valve 100 in such a manner that the fluid motors A, B can be driven in either of two directions and that, by reversing the fluid motors A, B, the turntable 18 can be driven through 360 in either a clockwise or counterclockwise direction simply by selectively positioning the reversing valve 100. The reversing valve is shown only schematically, since the structure thereof is conventional and well known to those skilled in the art.

Moreover, the admission of pressure fluid to fluid motors A, B in either direction automatically supplies pressure fluid to the brake cylinder port 119

past check valves

122 or 124, depending upon the direction the fluid motors A, B are being driven, for supplying pressure fluid to the brake cylinder 71 and thereby essentially simultaneously releasing the brake 66. So long as the fluid motors A, B are being operated in either direction the brake 66 is released. However, upon de-energizing the fluid motors A, B the return spring 86 operates to engage the brake and lock the countershaft 50 and the internally toothed bull wheel. The brake 66 will not be released until the fluid motors A, B are reaetuated.

Swing valve structure Referring to Figures 5, 6 and 7, the swing valve 99 comprises a generally rectangular housing 130 having a pair of parallel

cylindrical bores

131 and 132. Bore 131 is provided with

grooves

133, 134, 135, 136 and 137 spaced apart and separated by flange-

like lands

138, 139, 140 and 141, respectively.

The bore 132 is likewise provided with peripheral '6

grooves

143, 144, 145, 146 and 147 separated by

flangelike lands

148, 149, 150 and 151, respectively. A plug member 153 is threaded into an end 154 of bore 132, as best seen in Fig. 7. A plug member 155 is also threaded into a portion 156 in an end of bore 131 as best seen in Figure 8.

Referring to Figure 7, a cylindrical spool valve 158 is disposed in bore 132 of swing valve housing 130. The spool valve 158 has a cylindrical and axially extending opening or chamber 159 in an intermediate portion thereof. An enlarged axially extending opening 60 is formed in the outer end of spool valve 158. A conical opening 161 connects the

openings

159 and 160. A frusto-conical plug 162 seats in the conical or beveled opening 161 so that the chamber 159 and opening are partitioned and sealed oil? from each other. A transverse bore 163 adjacent the inner end of spool valve 158 communicates with the opening 160. A pair of spaced transverse bores 164 and 165, respectively, connect the chamber 159 with

peripheral grooves

144 and 145 when the spool valve is in its innermost position.

The outer end of spool valve 158 has an axially extending stem 166 rigidly connected thereto at one end thereof, the other end of the stem 166 being slidably guided within a cylindrical bushing 167 securely seated in a cylindrical bore 168 of a vented plug member 170. A cylindrical extension 171 connects the plug member with a threaded end 172 of bore 132. The plug 170 and extension 171 serve to enclose the outer end of the bore 132. A helical spring 173 encircles the stem 166 of spool valve 158 and seats against the outer end,

thereof and the adjacent end of cylindrical bushing 167 for biasing the spool valve 158 into the cylindrical bore 132. A channel 175 in housing 130 has a port 113 and connects with line 115 at one end thereof and fluid motor B via line 101, at the other end thereof.- The channel 175 has a pair ofbore holes 177 and 178 connecting it with peripheral grooves 143 and 147, respectively. The external ends of bore holes 177 and 178, respectively, are threaded for receiving

closure plug members

179 and 180. i

In Figs. 8 and 9 spool valve 188, similar to the spool valve 158, is slidably disposed in bore 131, the valve 188 havinga cylindrical, and axially extending opening or chamber 189 in an intermediate portion thereof. An enlarged axially extending opening 190 is formed in the outer end ofspool valve 188. A conical opening 191 connects the openings 189 and 190', and a frusto-conical plug 192 seats in the conical opening 191 so that the chamber 189 and opening 190 are partitioned and sealed off from each other. A transverse bore 193 adjacent the inner end of spool valve 188 communicates with the Opening 190. A pair of spaced, t-ranverse bores 194 and 195,

respectively, connect the chamber 189 with

peripheral grooves

134 and 135 when the spool valve is in its innermost position. The outer end of the spool 188 is also provided with an axially extending stem 196 similar to the spool valve 158, however, the plug member, plug extension and stem spring are not shown, since they are identical to those provided for spool valve 158.

The inner. and outer ends of each of the spool valves 158 and 188 are beveled for a purpose to be described. The housing 130 has formed therein a passage 200 formed by a transverse drill hole 201 and a longitudinal drill hole 202 intersecting therewith for connecting the groove 144 with line 102 of motor A. Hole 201. is

plugged at its outer end 203 in a conventional manner. A similar passage 204 is symmetrically formed in housing 130 for connecting groove 134 with line 103 of motor B, the passage 204 being formed of a transverse drill hole 205 and a longitudinal drill hole 206 with the outer end 207 of hole 205 being plugged in a conventional manner.

A longitudinally extending channel 210, similar to chan.-. nel 175, is formed in housing 130 to one side of and intermediately of

bores

131 and 132, see Fig. 5, the bore being connected to line 116 at one end and to line 104 of motor A at the other end thereof. A pair of passages 211 and 212, Fig. 8, are formed transversely of the housing 130 in a conventional manner for connecting channel 210 with

grooves

133 and 137, respectively. Channel 210 is connected to groove 1 46 by a passage 213 formed by a transverse drill hole intersecting groove 146 and channel 210 and plugging the outer end 214, Fig. 5, of the drill hole in a conventional manner. Similarly, the channel 175 is connected to groove 136 by a transverse drill hole for forming a passageway 215 with the outer end 216 thereof likewise plugged in a conventional manner. The

grooves

135 and 145 of

bores

131 and 132, respectively, have a common passage 218 formed by a drill hole obliquely disposed in the upper surface of housing 130. The outer end 219 of the drill hole or passage 218, which is counterbored, is plugged in a conventional manner.

Operation During the normal operation of the turntable 18 with the tool 22 substantially unloaded, the pump 96 feeds fluid through

lines

106, 109 of reversing valve 100, line 116, port 114, channel 210, and line 104 to the motor A, line 104 acting as an intake line in this case; the fluid is discharged from motor A through line 102, passage 200, groove 144, port 164, opening 159, port 165 of spool valve 158, through passage 218 to groove 135 of bore 131, port 195, opening 189 and port 194 of spool valve 188, to groove 134 and out passage 204 to line 103 leading to motor B, the line 103 serving as an intake line. The motors A and B are in this instance connected in series for low torque output and high speed operation.

Fluid is discharged from motor B via line 101, channel 175, port 113, line 115, line 110 in reversing valve 100, and line 118 to sump 97.

Since line 116 carries the high pressure fluid in this instance, fluid is fed to brake cylinder 71 for releasing brake 66 via lines 123 and 120, the check valve 124 being forced open and the check valve 122 being urged closed, since the fluid pressurein line 120 is greater than the fluid pressures in line 121 which connects with line 115.

The spool valves 158 and 188 are ordinarily spring biased closed or into their innermost positions in

bores

132 and 131, respectively, as by the spring 173 shown in Fig. 7 for biasing the spool valve 158 into its bore 132 and by fluid pressure acting on the outermost ends of the respective spool valves. However, once the tool 22, mounted on turntable 18 is loaded to such an extent that the torque output of the normally series connected motors A and B, is insufficient to drive the turntable, a substantial amount of backpressure will result. Usually this backpressure will build up'in a very short period of time, and take place in channel 210, Figures 8 and 9 and the passages 211 and 212. Since the surge of backpressure will occur in the passage 211 before it occurs in passage 212, the instantaneously high pressure surge will act upon the beveled inner end of spool valve 188 and force the latter toward the right-hand end of bore 131 a suflicient distance for the full end surface of the valves inner end to become exposed to the pressure fluid and thereby force the valve to the position shown in Fig. 9, so that the outer end of the spool valve 188 abuts against the adjacent end of its plug extension, not shown, but similar to the extension 171 in Fig. 7. So long as the fluid pressure in channel 210 and line 104, as well as in passages 211 and 212 remains at a high level, the spring is prevented from biasing the spool valve 188 inwardly for reconnecting the motors A and B in series.

The fluid path in swing valve 99, upon the spool valve 188 being shifted to the right for connecting the motors A, B in parallel is as follows: The fluid enters channel 210 from the pump 96, as hereinabove described, and fluid continues to be fed to motor A over line 104 as before. However, pressure fluid is now being channeled through passages 211, groove 133, spool valve end opening 190, port 193, passage 204, and line 103 to the motor B, line 103 still serving as an intake line; and fluid continues to be exhausted from motor B through line 101 and passage 175 back to the sump 97, as also hereinabove described. Motor A also exhausts fluid through line 102 to the swing valve in the manner before described with the exception that the fluid is fed to chamber 189 via transverse port 194 and therefrom viatransverse port 195, passage 215, and channel 175 to the sump along the path designated hereinabove. The motors A and B are, as a result, being operated in parallel at low speed with a high torque output for driving the turntable when the same is loaded.

The described flow paths of the pressure fluid through the control system, including the swing valve, serves to drive the motors A, B in one direction. However, upon actuating and readjusting the reversing valve 100, the flow of pressure fluid to the

swing valve ports

113 and 114 is reversed and the direction of drive of the motors A, B is likewise reversed. This is made possible by the symmetrical arrangement of the swing valve.

A modification of the fluid control system in Figure 2 is shown in Figure 10, wherein the aforementioned four-way valve has been replaced with a pair of twoway valves and an accumulator arranged in such a manner that a turntable brake 66 will be released when the turntable drive motors A, B are being driven by the pressure fluid and the turntable brake 66' is engaged when the turntable drive motors A, B are stopped.

Briefly, the modified system comprises a first two-way valve 230 shown schematically connected to a second two-way valve 231. The two-way valve 230 has a pair of passages 232 and 233 therein for connecting the discharge line 106 of pump 96 with the

lines

115 and 116, respectively, of swing valve 99. The swing valve is connected to the motors B and A via

lines

101, 103, and 102, 104, respectively, and the pump 96 draws fluid from the sump 97 by way of its intake line 98, as described hereinabove. The accumulator 234 is connected with line 116 by a line 235 which has a one-way check valve 236 disposed therein. The check valve 236 permits the pressure fluid to flow to accumulator 234, but prevents fluid from flowing therethrough in a reverse direction. The two-way valve 231 is connected to the accumulator for receiving fluid therefrom by means of line 237. A fluid line 238 connects two-way valve 231 with a modified brake cylinder 71 in a manner which will be described hereinafter. Also connected to the valve 231 is a line 240 which returns the pressure fluid to the sump 97. Two-way valve 231 is provided with a pair of lines 241 and 242, respectively, and a U-shaped conduit 243. Normally, the accumulator is not connected with the brake cylinder 71 when the fluid motors A and B are not being driven and the brake cylinder 71' normally discharges to return line 240 by way of the U-shaped conduit 243 in two-way valve 231.

Upon shifting the two-way valves 230 and 231 to the right sufiiciently to connect line 232 in valve 230 with discharge line 106 and line 115, the accumulator discharge line 237 is connected by the line 241 in two-way valve 231 to the intake line 238 of brake cylinder 71.

Alternatively, when it is desired to drive the motors A, B in a reverse direction, line 233 of valve 230 is connected to the pump discharge line 106 and, the line 116 leading to the swing valve 99. The foregoing shifting movement of the valve 230 to the left serves to also connect line 242 in valve 231 with the accumulator discharge line 237 and with the intake line 238 of the brake cylinder 71. It is in this position that the pressure fluid from pump 96 feeds to line 116 which connects with swing valve 99 and also supplies pressure fluid to the accumulator 234 by way 'of line 235, past one-way check valve 236, for charging or supplying the accumulator 234 with pressure fluid which is stored therein. As hereinabove pointed out, once the motors A, B are stopped by shifting the accumulator valves 2'30 and 231 to a central, neutral position, the brake cylinder 71" is relieved of pressure fluid by way of

lines

238, 243, and 240, back to the sump 97 and a spring loaded piston 72' is forced farther into the cylinder 71' for engaging the brake 66' of the drive mechanism.

While I have shown and described a specific embodiment in accordance with my invention, it is understood that the same is susceptible of many changes and modifications as known to a person skilled in the art, and I intend to cover all such changes and modifications coming within the scope of appended claims.

Having thus described my invention what I claim is:

1. A swing valve for connecting a pair of fluid pressure receiving means in parallel or in series with a fluid pressure source comprising, housing means having a pair of cup-shaped cylindrical bores formed therein, each of said bores including first, second, third, fourth and fifth peripheral grooves separated by flange-like lands, both of said third grooves being interconnected, a spool valve disposed in each of said cylindrical bores, means provided for biasing said spool valves into said bores, each of said spool valves having a first transverse opening near the inner end thereof communicating with a longitudinal opening in said inner end, and having sec nd and third transverse openings communicating witheach other internally of said spool valves and in non communicating relationship with said longitudinal openmg.

2. A valve as set forth in claim 1, wherein said one spool valve is provided with means for being automatically shifted toward one end of its bore.

3. A swing valve for connecting a pair of fluid pressure receiving means in parallel or in series with a fluid pressure source comprising, housing means having a pair of cup-shaped cylindrical bores formed therein, each of said bores including first, second and third peripheral grooves separated by flange-like lands, both of said third grooves being interconnected by a passage, a spool valve disposed in each of said cylindrical bores and provided with means for biasing said spool valves into and against the bottom of said bores, each of said spool valves having a first transverse opening near the inner end thereof communicating with a longitudinal opening in said inner end, and having second and third transverse openings permanently communicating with each other internally of each of said spool valves and in non-communicating relationship with said longitudinal opening, one of said spool valves being provided with means for being automatically shifted toward one end of its bore.

4. A swing valve for connecting a pair of fluid pressure receiving means in parallel or in series with a fluid pressure source comprising, a housing having a pair of cup-shaped cylindrical bores therein, each of said bores having first, second, third, fourth and fifth grooves separated by a plurality of flange-like lands, said housing having a first channel and a second channel, said first channel connecting said first and fifth grooves of one of said bores and said second channel connecting said first and fifth grooves of the other of said bores, said first channel being connected to the fourth groove of said other of said bores and said second channel being connected to said fourth groove of said one of said bores, and a pair of spool valves having means for the biasing thereof into said cup-shaped cylindrical bores, each of said spool valves being normally in abutment with the bottom of its bore, each of said spool valves having a first transverse opening communicating with a longitudinal opening in the end of said spool valve and interconnected second and third transverse openings in said spool valve in non'communicating relationship with said first 10 transverse opening, said second and third transverse openings of each of said spool valves normally'being in communicated relationship with said second and third grooves in said bores, said third grooves of said bores being interconnected by a passage.

5. A swing valve as set forth in claim 4 wherein said one spool valve is provided with means for being'automatically shifted axially away from the bottom of its bore.

6. A valve for connecting a pair of fluid pressure receiving means in parallel or in series with a fluid pressure source comprising housing means having a pair of cup-shaped cylindrical bores formed therein, each of said bores including first, second and third peripheral grooves separated by flange-like lands, both of said third grooves being interconnected, and a spool valve disposed in each of said cylindrical bores, each of said spool valves having a first transverse opening near the inner end thereof communicating with a longitudinal opening in said inner end, and having second and third transverse openings communicating with each other internally of said spool valves and in non-communicating relationship with said longitudinal opening.

7. A valve as set forth in claim 6', wherein said one spool valve is provided with means for being automatically shifted toward one end of its bore.

8. A valve for connecting a pair of fluid pressure receiving means in parallel or in series with a fluid pressure source comprising, housing means having at least one cup-shaped cylindrical bore formed therein, said bore including first and second peripheral grooves separated by a flange-like land, and a spool valve disposed in said cylindrical bore and provided with means for the biasing thereof into said bore, said spool valve having a first transverse opening near the inner end thereof communicating with a longitudinal opening in said inner end, and said spool valve being provided with means for being automatically shifted toward one end of its bore.

9. A swing valve for connecting a pair of fluid pressure receiving means in parallel or in series with a fluid pressure source comprising a housing having a pair of cupshaped cylindrical bores therein, each of said bores having first, second and third grooves separated by flange-like lands, a conduit disposed in said housing, said conduit connecting said first groove of one of s-aid bores therewith, and a pair of spool valves having means for the biasing thereof into said cup-shaped cylindrical bores, said spool valves being normally in abutment with the bottom of said bores, each of said spool valves having a first transverse opening communicating with a longitudinal opening in the end of said spool valve and interconnected second and third transverse openings in said spool valve in non-communicating relationship with said first transverse opening, said second and third transverse openings of each of said spool valves normally being in communicated relationship with said second and third grooves in said bores, said third grooves of said bores being mutually interconnected.

10. A swing valve as set forth in claim 9 wherein said one spool valve is provided with means for being automatically shifted axially away from the bottom of its bore.

11. In a drive mechanism for a material handling apparatus, in combination, at least two fluid driven motors operatively connected for driving at least one output shaft, a fluid pressure source for supplying fluid under pressure to said motors, valve means interposed between and operatively connected to said motors and said fluid pressure source to pass pressure fluid flowing to the intake side of each of the motors and to pass pressure fluid flowing from the exhaust side of each of the motors, said valve means including a movable part engaging said pressure fluid, said part being movable solely by the fluid engaging said part in response to a preselected increase in the pressure of said fluid from a first position 11 wherein the part connects the motors in series for low torque and high speed operation to a second position wherein the part connects the motors in parallel for high torque and low speed operation.

12. A drive mechanism for a material handling apparatus as defined in claim 11 in combination with a four-way valve interposed between the fluid pressure source and said valve means for reversing the flow of pressure fluid therein and thereby reversing the direction of fluid flow in said motors.

References Cited in the file of this patent UNITED STATES PATENTS Francis June 11, 1929 Kennedy Nov. 10, 1936 Robinson Mar. 4, 1947 Robinson Feb. 13, 1951 Kanuch Ian. 12, 1954 Thomas Oct. 1, 1957