US3470968A

US3470968A - Horizontal boring machine

Info

Publication number: US3470968A
Application number: US667224A
Authority: US
Inventors: Ted R Melsheimer; Richard F Melsheimer
Original assignee: RICHARD F MELSHEIMER; TED R MELSHEIMER
Current assignee: RICHARD F MELSHEIMER; TED R MELSHEIMER
Priority date: 1967-09-12
Filing date: 1967-09-12
Publication date: 1969-10-07
Anticipated expiration: 1986-10-07

Description

Oct. 7, 1969 T. R. MELSHEIMER ETAL 3,470,968

HORIZONTAL BORING MACHINE .5 Sheets-Sheet 1 Filed Sept. 12. 1967 IN VEN TOR 750 P. MELSHE/MER, R/

CHA RD E MEL SHE/MER 5y Eon A20 D. O'BR/A/v 7 MER mum/foes 7E0 R. MEL SHE/MEI? 5 Sheets-Sheet 2 R/cHA 120 F MELSHE/ EDWARD D. GER/AN T. R. MELSHEIMER ETAL HORIZONTAL BORING MACHINE VIIIIIIIIIIIA Oct. 7, 1969 Filed Sept. 12, 1967 ATTORNEY Oct. 7, 1969 1; E H M ETAL 3,470,968

HORIZNTAL BORING MACHINE Filed Sept. 12, 1967 5 Sheets-Sheet 5 FIG. 4

mum/7025 72:0 R. M51. SHE/MEI? RICHARD FMELsHE/Mm ay fan/A20 D. OER/AN Awoe/vsy Get. 7, 1969 MELSHEMER ErAL 3,470,968

HORIZONTAL BORING MACHINE I Filed Spt. 12, 1967 s Sheets-{Sheet 4 lNl/E/V 7025 7'50 R MEL SHE/MEIR,

R/CHARD FMELSHE/MER B EDWARD D. O'BR/AN ATTOEA/EY Oct. 7, 1969 MELSHEMER ETAL 3,470,968

HORIZONTAL BORING MACHINE Filed Sept. 12. 1967 5 Sheets-Sheet 5 lNl/EA/TOES f 750 R MELfi/YE/MER,

P/CHAED F. Mas/15mm? EDWARD D. O'BR/A/v A 77'02NEY United States Patent 3,470,968 HORIZONTAL BORING MACHINE Ted R. Melsheimer, 1924 Isabella Ave., and Richard F. Melsheimer, 524 Almora, both of Monterey Park, Calif. 91754 Filed Sept. 12, 1967, Ser. No. 667,224 Int. Cl. E21c 11/02; E2111 19/00, 21/04 U.S. Cl. 173--24 2 Claims ABSTRACT OF THE DISCLOSURE The horizontal drilling machine is particularly arranged for positioning on the ground surface and rotating and advancing a drill string. The drill pipe is sufficiently flexible to permit the pipe to enter a drilling pit and then proceed horizontally from the pit for drilling a horizontal hole for later pipe insertion. For proper control of drilling the horizontal drilling machine has hydraulically powered propulsion along the ground surface, together with selectable one or two wheel drive fixed to the drive axle. Furthermore, hydraulic power rotates the drill string so that optimum control of drill rotation and drill advance are both obtained. Water injection through the drill string is often helpful in such drilling. In the present horizontal drilling machine, a water-oil heat exchanger is employed to cool the hydraulic oil used for the propulsion and drill rotation. Furthermore, a water reservoir is employed, which is filled from any conventional source. A float operated valve controls such filling. A separate water pump is provided, together with pressure controls therefor, so that pressure of Water to the drill string can be controlled for optimum water flow.

Background The horizontal boring machine of this invention lies in those classes of machines which are arranged for boring horizontal holes in the earth for the subsequent installation of pipes.

There are machines in the prior art which accomplish the same generalized purpose. The prior machines, however, require that the means for rotating the drill be located so that the drill can move horizontally into an earth face in which the drilled hole is desired. For the most part, this requires the digging of a pit and the placement of at least the drill rotating structure, together with the drill string in the pit. In some cases the advancement of the drill string is accomplished from structure exteriorly of the pit, and in some cases the entire advancement and drill rotating structure must be located in the pit. This requires a relatively large pit, at least as long as the length of the drilled hole. When a pipe is to be placed, this requires that at least half of the length of the installation must be dug into trench or pit form. The net result is that such drilling is only useful in drilling under short fixed obstructions, such as sidewalks and driveways.

Summary The horizontal boring machine of this invention thus comprises a power unit which is placed upon the top of the ground surface. This boring unit has both a drill rotating unit thereon and a propulsive unit thereon for propelling the entire power unit along the ground, Both are hydraulic powered for the infinite control that such powering provides. The drill rotating unit is mounted at the front of the power unit and is arranged so that a moderately flexible drill string can be rotatively driven thereby. This drill string is sufiiciently flexible that it can bend into a short trench, and thence horizontally out of the trench so as to drill a horizontal hole away from the trench. This permits a relatively long string of drill pipe and a relatively long horizontal drilling accomplishment with a relatively short trench. Since the power unit moves along the surface of the ground, the length of the trench need not be as great as the length of the drilling operation. Instead, long drilling can be accomplished employing only a short trench. Additionally, water cooling is provided for the hydraulic system. The cooling employs the water which is injected through the drill string to aid in drilling. The power unit is an integrated structure which employs a hydraulic power supply with separate controls for drilling and for drill advancing and a fully controlled water system for hydraulic oil cooling and for drilling.

It is thus an object of this invention to provide a horizontal boring machine which provides fully controlled operation for optimum horizontal boring, including drill rotation and drill advance. It is another object of this invention to provide a horizontal boring machine which comprises a power unit including drill rotating structure which is supported upon and advanced along the ground for drilling of horizontal underground holes by means of an elongated drill string which enters the ground through a fairly short trench. It is another object of this invention to provide a power unit which employs a Water system which discharges water through the drill string for aid in drilling, the water system having its own pump and reservoir to provide water under pressure at optimum conditions of pressure and flow, and which water is also used for cooling the hydraulic power supply which provides drill rotation and power unit propulsion. It is another object of this invention to provide a horizontal boring machine which has selective propulsion along the ground, including a low speed for more diflicult boring operations with larger boring bits, and a selectable higher speed for normal transit into position, and which propulsion mechanism includes a driving axle with a single wheel fixed thereto and with a second wheel selectively fixable thereto so that positive traction can be obtained with one or two ground engaging Wheels. It is a further object of this invention to provide an economically constructed but fully controllable horizontal boring machine whereby boring can be controlled by one man. It is another object of this invention to provide a horizontal boring machine which is economic of construction, convenient and easy to use and of long life so as to readily and economically bore horizontal holes in the ground. Other objects and advantages of this invention will become apparent from the following portion of this specification, the claims and the attached drawings.

Description of the drawings FIG. 1 is a side elevational view of the horizontal boring machine of this invention.

FIG. 2 is a top plan view thereof.

FIG. 3 is a front end elevational view thereof.

FIG. 4 is an enlarged top plan view, with parts broken away, showing the horizontal propulsion mechanism 01 the boring machine.

FIG. 5 is an enlarged section taken generally along the line 5-5 of FIG. 4.

FIG. 6 is an enlarged section taken generally along thr line 6-6 of FIG. 4.

FIG. 7 is an enlarged section taken generally along tllt line 7-7 of FIG. 4.

FIG. 8 is an enlarged side elevational View, with part: broken away, showing the stiff leg jack.

FIG. 9 is an enlarged section taken generally along the line 9-9 of FIG. 8.

FIG. 10 is an enlarged vertical section taken througl the drill rotating head of the boring machine, generally along the line 10-10 of FIG. 3.

FIG. 11 is a schematic isometric view of the hydraulii circuit which powers the drill rotation on the boring machine.

FIG. 12 is a schematic isometric view of the hydraulic circuit which powers the advance of the boring machine. FIG. 13 is a schematic isometric view of the water circuit which cools the hydraulic oil and which supplies water under pressure to the drill head.

Description In FIGS. 1, 2 and 3, the horizontal boring machine of this invention is generally indicated at 10. It has a chassis 12 which serves as a structural means for supporting all of its parts, and serves as a reservoir, as hereinafter described. Mounted upon the chassis is prime mover 14 which serves as a prime power source for propulsion of the horizontal boring machine along the ground surface and for power to rotate the drill.

Front wheels

16 and 18 are steerably mounted upon front axle 20 which is mounted to the front of chassis 12 by means of pivot 22. This pivot permits the front axle 20 to swing upon the longitudinal axis of the boring machine to thus permit the boring machine to equalize its weight upon all four wheels on uneven ground. Steering linkage 24 is connected to steering wheel 26 so that the operator positioned adjacent the steering wheel can direct the orientation of the machine as it progresses.

The rear of boring machine 10 is supported upon its

drive wheels

28 and 30. The drive wheels, in turn, are mounted upon axle 32 which is rotatably mounted with respect to the rear of chassis 12. Hub 34 is fixed to axle 32 so that positive drive is obtained when the axle rotates. Brake drum 36 is fixed to axle 32. Brake drum 36 is in the form of a V belt pulley, and brake band 38 extends around the brake drum, see FIG. 7. One end of brake band 38 is fixed by link 40 to frame 42 which forms part of the chassis. Brake lever 44 is also pivoted to frame 42 and is urged upward by means of spring 46. The other end of brake band 38 is secured to brake lever 44 by means of link 48. Operation of brake lever 44 by having the operator press his foot thereon causes tightening of the brake band about the brake drum 36 to lock rotation of axle 32 and stop motion of the boring machine 10.

As is seen in FIGS. 4 and 5, outboard of

sprockets

50 and 52, which are fixed to axle 32, drive wheel 30 is mounted upon axle 32. Drive wheel 30 is mounted upon hub 54 which in turn is mounted upon bearing housing 56.

Bearings

58 and 60 are mounted between axle 32 and bearing housing 56 so that hub 54 is freely rotatably mounted upon axle 32. By this construction, the horizontal boring machine 10 can turn corners without dragging a drive wheel. Furthermore, since drive wheel 28 is fixed to the axle, normal propulsion on firm surfaces is obtained so that this is sufficient for many horizontal boring jobs. However, in those cases where the ground surface is soft and traction is poor, it is desirable to irrotatably fix hub 54 upon axle 32. Spline 62 is integrally formed on the end of axle 32 and extends out of bearing housing 56. A cap or locking hub 64 has a spline opening therein to receive spline 62 and is arranged to be bolted upon the end of bearing housing 56 to thus irrotatably fix the bearing housing and hub 54 with respect to axle 32. When fixed in this manner, drive wheel 30 also serves as a ground engaging propulsion wheel. Instead of a plain cap 64, a commercial coupling can be used.

In order to aid in the installation of cap or locking hub 64 it is desirable to raise the wheel 30 off the ground so that it can be rotated for alignment of the engagement splines within the cap or locking hub 64 and alignment of the bolt holes in the cap with the corresponding holes in the bearing housing 56. This is accomplished by means of stiff leg jack 66.

As is seen in FIGS. 8 and 9, stiff leg jack 66 comprises leg 68 which is pivoted upon pivot 70 which is secured 4 to bracket 72. Bracket 72 includes stop 74 which limits the rotative travel of leg 68 in the clockwise direction. Additionally, opening 76 is positioned on leg 68 for the reception of stop pin 78 which can be engaged in opening 76 to restrain leg 68 in a position where it is clear to the ground, as is illustrated in FIG. 1. Stop pin 78 is spring urged towards engagement within opening 76 and can be held out of engagement by means of a transverse pin (not shown) across stop pin 78 which can be selectively engaged in a corresponding slot in bracket 72.

When it is desired that wheel 30 be raised for the purpose of locking it to axle 32, stop pin 78 is disengaged from its opening 76 and leg 68 is permitted to rest upon the ground or other supporting surface. When the boring machine 10 is driven forward by means of coupled wheel 28 and as it moves forward, the portion of the boring machine adjacent the jack leg 66 is raised to raise wheel 20 off of the ground. The wheel can then be freely rotated for locking the coupling or placing cap 64 in place.

Referring to FIG. 4, motor 80 is a hydraulic motor powered from a hydraulic source hereinafter described. Motor 80 is connected to drive reduction gear box 82 which has output sprocket 84 connected to its output shaft. Chain 86 engages upon sprocket 84 and upon sprocket 88 which is mounted on counter shaft 90. Counter shaft 90 is suitably rotatably mounted upon the chassis 12.

Sprockets

92 and 94 are rotatably mounted upon the counter shaft and are respectively connected by

chains

96 and 98 to drive

sprockets

50 and 52. Clutch 100 is mounted to rotate with the shaft on the square portion of the shaft illustrated in FIG. 6. The clutch 100 has four round pins 101 which protrude from its side. These pins 101 engage mating faces upon the facing sides of the

sprockets

92 and 94. Thus, by shifting the clutch 100, drive from the motor to axle 32 is selectable through chain 96 or chain 98. Due to the fact that

sprockets

92 and 94 are different size, different speed ratios are obtained. Yoke 102 engages clutch 100 to move it from one engagement to the other. Handle 104, see FIGS. 1, 2 and 3, is accessible to the operator of the boring machine to permit him to select this ratio.

As is seen in FIGS. 1, 2 and 3, prime mover 14 is an internal combustion engine 106 which is directly connected to drive hydraulic pump 108. Pump 110 is a water pump connected by suitable pulleys and belt 112 so that it is also driven by engine 106. The fluid connections of these pumps will be later described.

As is seen in FIGS. 1, 2 and 3, support

arms

114 and 116 are upstandingly mounted on the front of chassis 12. They carry aligned pivot bearings adjacent their tops, which pivot bearings define a raised transverse pivot axis. Mounted on this pivot axis is drill driver 118. Drill driver 118 comprises a housing 120, see FIG. 10, from which aligned trunnions 121 laterally extend. These aligned trunnions 121 are mounted in the pivot bearing 123 in the support arms so that the drill driver can swing upon that horizontal axis.

Hydraulic motor 122 is flange mounted on the rear of housing 120. The connections of hydraulic motor 122 will be later described. Hydraulic motor 122 has an output shaft which extends through the housing and is preferably supported by a bearing on the front wall of housing 120. The output shaft to motor 122 is indicated at 124. Shaft 124 carries pinion gear 126. Idler shaft 128 is rotatably mounted on bearings in the front and rear walls of housing 120. Idler shaft carries gear 130, fixed thereto, which is in gear tooth mesh with pinion gear 126. Furthermore, idler shaft carries fixed thereto drive sprocket 132 which thus rotates with motor rotation. Drill shaft 134 extends through housing 120 and is rotatably mounted with respect thereto on

bearings

136 and 138. Sprocket 140 is fixed on drill shaft 134, between its bearings, and chain 142

interconnects sprockets

132 and 140. The pinion gear 126 and gear together with sprockets 132 and act as a speed reduction so that drill shaft 134 rotates at a slower speed than motor shaft 124.

Instead of using sprockets and chain in this speed reduction mechanism, gears alone could be used. Changes in the reduction ratio can be obtained to aid in changes in the speed ratio by changing the

gears

126 and 130. The cover 144 and the caps on

bearings

136 and 138 are easily removable. Changes in ratio are rarely needed, but one ratio is satisfactory for nearly all of the boring that a particular boring machine will be employed to perform. Thus, a quick change gear box is not necessary, particularly in view of the variable speed capability of hydraulic motor 122. Housing 120 is preferably totally closed, when cover 144 is in place, so that it can contain oil for lubrication of the gears, chain and bearings.

Drill shaft 134 has a passage 146 therethrough. At the rear of drill shaft 134, union tube 148 is rotatably fitted. Union tube 148 provides a rotating joint of such nature that the union tube can remain stationary while shaft 134 rotates. The front end of shaft 134 carries threads and upon these threads are mounted adaptor 150. Adaptor 150 in turn is arranged to be threaded into the end of a string of drill pipe 152. The drill pipe string 152 can be assembled to be as long as needed for the job, by screwing lengths of drill pipe together. The outer end of the drill pipe string carries the drilling bit which actually performs the drilling operation. Adaptor 152 is provided to permit the ready attachment of different sizes and styles of drill pipe 152 onto the end of shaft 134. Furthermore, the use of the adaptor protects the threads on the end of shaft 132 from excessive wear. Adaptor .150 and drill pipe string 152 are tubular so that water can be conveyed to the drilling bit on the outer end of the drill pipe string.

In order to restrain adaptor 150 from rotation so that the drill pipe string 152 can be unscrewed therefrom, when it is necessary to make changes in the drill pipe string, lock 154 is provided. Base plate 156 is secured to the bottom of housing 120 and extends forward to support lock tube 158. Lock arm 160 is slidably mounted in tube 158 and is bifurcated at its upper end to provide

jaws

162 and 164, see FIG. 3. Flats 166 are provided on the exterior of adaptor 150 so that when lock arm 160 and its jaws are moved upwardly, the jaws engage around the flats 166 to thus prevent the adaptor from rotating. In this condition the drill pipe can be removed or otherwise acted upon. Furthermore, the adaptor can be easily unscrewed from the drill shaft by using this lock and rotating the motor in the reverse direction.

Referring to FIGS. 11 and 12, it is seen that the chassis 12 is comprised of

rectangular reservoirs

168 and 170. Reservoir 168 is a water reservoir while reservoir 170 is a hydraulic reservoir. Pump 108 draws oil from the reservoir through suction line 172 and discharges it into pressure line 174. The pump .108 is preferably a variable volume pressure compensated pump which can be preset to pump the required volume of hydraulic fluid at a desired pressure. A pump case drain returns internal leakage from this pump 108 back to oil reservoir 170. Pressure line 174 is connected to manifold 178 which supplies several hydraulic needs.

In FIG. 11, line 180 receives hydraulic fluid under pressure from manifold 178 and delivers it to reversing valve 182. Valve 182 has a manually operable handle 184, see FIGS. 1 and 2, for control of the spool in the valve. Motor lines 186 and 188 are connected between valve 182 and motor 122 and are arranged so that upon shifting of the spool in valve 182, fluid under pressure is delivered through one of these motor lines while the other is connected to exhaust back into the reservoir. The pressure and exhaust functions of these lines can be reversed by valve 182 to cause reversal of motor 122. Motor 122 also has a case drain 190 which drains internal motor leakage back to the reservoir 170. The returning hydraulic fluid from motor 122, through valve 182, passes 6 through exhaust line 192. Exhaust line 192 discharges to oil cooler 194 which is attached to the side of reservoir 170 and has an external connection discharging the oil from the cooler into the reservoir 170. By this means the stopping and reversing of motor 122 is accomplished.

Referring to FIG. 12, the pump 108, pressure line 174 and pressure fluid manifold 178 are again seen. Pressure gauge 196 is connected to the manifold to indicate to the operator the amount of hydraulic fluid pressure available to motors and 122. Bypass valve 198 is connected by line 200 to the manifold 178 and discharges to exhaust line 192. The control of flow through valve 198 controls the pressure in manifold 178 by bypassing oil back to the reservoir. Thus, by manual control of this valve, the amount of fluid pressure available to both the motors is controlled.

A needle type valve 202 is connected by line 204 to the manifold 178 and is connected by line 206 to manually operable reversing valve 208. Handle 110, see FIG. 2, is at the operators position so that the operator can conveniently manually control valve 208.

Motor lines

212 and 214 are connected between the valve 208 and motor 80. Valve 208 is arranged so that the position of handle 210 directs hydraulic fluid under pressure into lines 212 or line 214, while connecting the other line to exhaust. Exhaust line 216 is connected between valve 208 and exhaust line 192 to handle this exhaust flow. Additionally, motor case drain line 217 is connected from the case of motor 80 to reservoir 170 to drain internal leakage from the motor back into the sump.

The

reservoirs

168 and 170 are also illustrated in FIG. 13, wherein the water system is described. Connection is provided at 218 for any convenient source of water under pressure. Preferably a hose from a city water supply or the like is connected at 218. Valve 220 is a shut off valve which permits the water to flow into line 222. Valve 224 is operated by float 226 which is positioned inside of reservoir 168 and the float and valve act to maintain a constant level of water within reservoir 168. Line 228 connects the discharge from valve 224 to oil cooler 194. Water and oil are prevented from mixing in oil cooler 194 by shell and tube construction or the like. Line 230 directs the water from the oil cooler into reservoir 168. Air vent 232 permits air to flow in and out of the reservoir in accordance with the changes in level of water therein.

Suction line 234 extends to the bottom of the reservoir and serves as a pump suction line. Pump suction line 235 is connected to the inlet of pump 110. Filter 236 protects the pump against contaminents in the reservoir. Water is discharged under pressure from pump 210 into pressure line 236. Pressure line 236 is connected to line 238 which has both a relief valve 240 and an orifice connected in parallel to exhaust line 244. The flow from both of these devices returns to reservoir 168 through exhaust line 244. By this means, the pump 110 is protected against over pressure and a certain minimum flow is always permitted through orifice 242 to prevent air lock of the pump. The main discharge from pressure line 236 goes through line 246 which carries pressure gauge 248 thereon. Additionally, line 246 extends to manually operable control valve 250 which controls the water flow from line 246 to line 252. Line 252 is at least partly flexible and is connected on its outer end to union tube 148. By this means the pressure and flow of water to the drill bit is controlled to discharge the optimum amount of water for best drilling.

In operation, when a hole is to be bored horizontally under the surface of level ground, a pit is dug to slightly more than the desired depth of the desired hole. The length of this pit depends on the flexibility of the drill pipe string 152. A fairly flexible drill pipe string can be used in most cases. The outer end of the drill pipe string carrying the drill bit, is aligned in the bottom of this pit so that drilling will proceed in the proper direction. Thereupon, after starting the engine 106, drilling proceeds. Motor 122 is started by operation of handle 184. Water is started by opening

valves

220 and 250, with valve 250 being opened to the extent necessary to provide a proper Water volume. Thereupon, valve 208 is operated by handle 210 so that the boring machine 10 proceeds forward to push the string of drill pipe ahead of it. The rotary speed of the drill head (or drill driver) is controlled by varying the throttle setting on the engine; in other Words, the rotary speed of the driver is proportional to the volume of oil delivered which in turn is determined by the r.p.m. of the engine and pump. The by-pass valve 198 is used as a throttling valve only under conditions demanding exact control of direction or rotary speed.

As drilling proceeds as described in the preceding the gauge 196 can be used as an instrument by an operator in determining proper operation of the complete machine 10. In general it has been found that boring operations can be most effeciently performed within a range of pressures as shown by this gauge 196 which is lower than a range of pressures as shown by this gauge 196 which has proved to be most efiicient for reaming. A relatively constant pressure as shown by this gauge 196 can be maintained by opening and/or closing the bypass valve 198. This is considered to be quite important.

If a larger hole is desired, a reamer is placed on the end of the drill string, and while the drill string is being withdrawn, the hole is enlarged. At the same time, either a pipe pulling cable or the pipe itself can be pulled through the hole while the drill string is being withdrawn. When drilling is to be accomplished in relatively soft ground wheel 30 is locked to the axle by means of cap 64. This is accomplished by raising wheel 30 on stitf leg jack '66 and locking the hub r cap 64 so the wheel is fixed. Thereupon, the boring machine is driven off the jack 66 and the boring machine is propelled by having both drive wheels fixed to the shaft.

We claim:

1. In a horizontal boring machine, said horizontal boring machine comprising:

a chassis,

wheels on said chassis for supporting and propelling said chassis along the ground,

a hydraulic reservoir mounted on said chassis,

power means mounted on said chassis,

a hydraulic pump connected to said power means and connected to said reservoir to draw hydraulic fluid from said reservoir and discharge it under pressure,

the improvement comprising:

a boring string supported on said chassis so as to extend therefrom,

a drill motor mounted on said chassis, said drill motor being arranged to be connected to a boring string for rotation of the boring string, said drill motor being connected to said hydraulic pump for powering thereby,

a propulsion motor on said chassis, said propulsion motor being connected to at least one of said wheels so that rotation of said propulsion motor propels said chassis along the ground, said propulsion motor being connected to said hydraulic pump to be powered thereby,

a water reservoir is mounted upon said chassis,

a water pump is connected to said power means to to driven thereby, said water pump being connected to draw water from said water reservoir and to discharge it through the drill string,

a heat exchanger is mounted upon said chassis,

said heat exchanger being connected to said water reservoir and to said oil reservoir so that water cools the oil.

2. The horizontal boring machine of claim 1 including:

a float mounted in said water reservoir,

a water inlet valve connected to said reservoir and connected to said float to be controlled thereby and arranged so that said float shuts off said Water inlet valve to prevent overfilling of said water reservoir, a heat exchanger connected to the Water outlet of said water inlet valve being said heat exchanger being connected so as to discharge water into said water reservoir so that Water passing through said water inlet valve passes through said heat exchanger and thence into said water reservoir.

References Cited UNITED STATES PATENTS 2,656,152 10/1953 Moon 173-27 2,807,441 9/1957 Sewell 17327 2,985,250 5/1961 Goodrich et a1. 17327 X 3,291,225 12/1966 Foran 173-164 ERNEST R. PURSER, Primary Examiner US. Cl. X.R.

@335 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,470 .968 Dated October 7, 1959 Inventor) Ted R. Melsheimer and Richard F. Melsheimer 7 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 6 line 19 "l 10' should read --2l0--; column 6

line

48, 235" should read --234--; column 6 line 39 P236" should read --235--; Column 6, line 51, 210' should read --l l0--; column 6 line 53 "ori f1 ce" should read "orifice 242".

SIGNED Auu SEALED JAN 204970 Attest:

Edward M. Fletcher, Ir.

WILLIAM E. 50mm, .13. Atteating Offxcer Gamiasioner of Patents