US2005018A - Hydraulic actuating mechanism for planers - Google Patents

Description

June 18, 1935.

D H. WEST ET AL HYDRAULIC ACTUATING MECHANISM FOR PLANERS Filed Sept. 28, 1931 6 Sheets-Sheet l i f 5 WM r June 18, 1935. D. H. WEST Er AL 2,005,018

HYDRAULIC ACTUATING MECHANISM FOR PLANERS Filed Sept. 28. 1931 6 Sheets-Sheet 2 O jaw-11%,, M

June 18, 1935. D. H. WEST ET AL.

HYDRAULIC ACTUATING MECHANISM FOR PLANERS Filed Sept. 28, 19.71 6 Sheets-Sheet 3 hnn - 45;, Ma hem June 18, 1935. WEST ET AL HYDRAULIC ACTUATING MECHANISM FOR PLANERS 6 Sheets-Sheet 4 Filed Sept. 28, 1951 June 18, 1935. D, H. WEST ET AL HYDRAULIC ACTUATING MECHANISM FOR PLANERS 6 Sheets-Shet 5 Filed Sept. 28, 1951 June 18, 1935. D. H. WEST E1 AL 2,005,018

HYDRAULIC ACTUATING MECHANISM FOR PLANERS Filed Sept. 28, 1951 6sheets sheet e 02: lye/1 2 70 Z 02a Aazzw Patented June 18, 1935 UNITED STATES PATENT OFFICE Donald H. West, Marlboro, and Kenneth 0. Monroe, Hudson, Mass., assignors to The Lapointe Machine Tool Company, Hudson, Masa, a corporation of Maine Application September 28, 1931, Serial No. 565,420

6 Claims.

This invention relates to mechanism for actuating the reciprocating table or carriage of a planer or other machine tool. The use of high speed tools in such machines renders much higher 5 table speeds desirable, in order to fully utilize the advantages of the improved tools.

It is the general object of our invention to provide improved table-operating mechanism so designed that increased table speed is available 10 and that smooth and rapid reversal may be accomplished.

A further object is to provide actuating mechanism which may be conveniently adjusted to vary the speed of the cutting stroke, the return speed and the rates of deceleration and acceleration at the reversal of each stroke.

We also provide mechanism by which the permissible ratio of deceleration and acceleration are much increased, which result is facilitated by eliminating the reversal of heavy rotating parts.

Our invention further relates to arrangements and combinations of parts which will be hereinafter described and more particularly pointed out in the appended claims.

A preferred form of the invention is shown in the drawings, in which Fig. 1 is a side elevation of a planer embodying our improvements;

Fig. 2 is a diagrammatic plan view showing the hydraulic actuating mechanism and connections, together with the control devices therefor, and

Figs. 3, 4, 5 and 6 are similar diagrammatic views illustrating different operating conditions.

Referring to Fig. 1, we have shown a planer having a base ID on which a table T is guided for longitudinal sliding movement. A cylinder I3 is mounted in fixed position in the base I and a piston I4 is slidable in the cylinder i3 and is connected by a piston rod l5 to the right hand end of the table T, as shown in Fig. 2.

When oil or other liquid under pressure is admitted to the cylinder space IS, the table T is moved to the right for an operative movement, carrying the work under a suitable tool K.

When liquid is admitted to the annular cylinder space I! surrounding the piston rod IS, the table T is moved to the left at relatively high speed.

Our improved planer is equipped with a suitable driving motor M which continuously rotates a relatively large table-operating pump P and a relatively small control or pilot pump P. The planer is also provided with an automatic reversing valve mechanism V, a speed control and main differential valve mechanism V, a control mechanism V for the pump P, and hydraulic tool feed mechanism D. The automatic reversing valve mechanism V may be operated as usual by dogs 20 mounted on the table T and engaging an oifset arm 2| on the piston rod 22 of the reversing valve mechanism V.

General operation prior patent to West, No. 1,722,832. The direction and rate of flow of oil to the cylinder I3 is controlled by reversing the discharge of the pump P, 1

the connections between the pump and the cylinder remaining unchanged during operation of the planer.

The auxiliary or pilot pump P is preferably of the same general type as the pump P, but is arranged to automatically maintain constant pressure in its discharge pipe and the discharge is never reversed, although it may be brought to zero after the predetermined pressure has been attained and in case there is no demand on the pump.

The reversing valve mechanism V changes the connections to the pump control mechanism V and the mechanism W operates to reverse the direction of flow of the pump P. The speed control and main differential valve mechanism V may be set manually for either fast or slow speed operation of the cylinder on the cutting stroke, but without affecting the speed of the return stroke.

Provision is also made for automatically raising the tool from the work on the return stroke and for feeding the tool after each cut. The tool feeding mechanism D may be adjusted manually to feed at the beginning of the return stroke or at the beginning of the cutting stroke, as may be preferred, and may be adjusted to vary the rate of feed.

The connections and operation of the pump control mechanism W are very important, as they determine the rate of movement of the reversing mechanism for the pump P and thus determine the rate of deceleration and acceleration of the table T. flFm'thermore, these connections may be independently adjusted to increase or decrease the rate of either deceleration or ac- Pump mechanism As previously stated, the pumps P and P are preferably of the type shown in the West Patent #1,722,832 and may be briefly described as follows:

The pump P comprises a casing (Fig. 2) having plurality of pistons 5| slidable in a rotating cylinder block 32 and connected to a plate 53, rotatably mounted in a tilting holder or cradle 34.

The cradle 34 is provided with segment gear teeth 55 engaged by a pinion 55 mounted on a shaft 31 having bearings in the upper part of the casing 35 and engaged by a rack bar 55 mounted on a rod 35 which is slidable in a bearing 45 and is connected to a piston 4| and cylinder 42 forming part of the control valve mechanism V When the piston 4| is at one end of its path of travel, as shown in Fig. 2, the pump P will operate to discharge oil. into an upper discharge pipe 44, and when the piston 4| is at its opposite limit of travel, as shown in Fig. 3, the pump P discharges oil from a lower discharge pipe 45.

The piston 4| has only three operative positions, shown in Figs. 2, 3 and 6 respectively, and these positions represent cutting, return and neutral operating conditions.

The pipe 44 is connected to the left hand end of the cylinder I3, as shown in Fig. 2, \and is provided with a check valve 41 opening toward the cylinder I3. The pipe 44 is also preferably provided with a by-pass 45 having an adjustable shut-off valve 45 by which the rate of discharge from the cylinder space I5 may be controlled, so that a suiiicient back pressure may be provided on the return stroke to insure smooth working of the table.

A pipe 55 connects the pipe 44 to the speed control valve mechanism V to which the lower pump connection 45 is also attached. A branch connection 5| between the pipes 44 and 45 is normally closed by a shut-off valve 52.

The right hand end of the cylinder i5 is connected by a pipe 54 to the speed control valve mechanism V and is provided with a check valve 55, by-pass 55 and adjustable shut-off valve 51, all as previously described in relation to the pipe 44.

When the mechanism is set for a slow speed cutting stroke, as shown in Fig. 2, oil is delivered from the pump P through the pipe 44 and past the check valve 41 to the cylinder space I5 in the cylinder I3, while the annular space I! in the cylinder I3 is connected through the pipe 54 and by-pass 55 to the speed control valve mechanism V.

On the return stroke, the parts take the position indicated in Fig. 3, and the flow of oil is reversed, entering the annular cylinder space I1 and being discharged from the cylinder space I5.

Reversing valve mechanism The reversing valve mechanism V comprises a casing 55 having a cylindrical opening 51 in which pistons 52, '53 and 54. are slidable, these pistons being mounted in spaced'relation onthe rod 22 previously described.

The pilot pump P delivers oil at constant pressure through a discharge pipe 55 (Fig. 2) to a port 51 in the casing 01 the cylinder 5|. A discharge port 55 in the cylinder 5| is connected by a discharge pipe 55 to an over-flow or storage tank S. The discharge pipe 55 may be provided with a gauge 15 and strainer II Ports l2 and I5 in the cylinder 5| are connected together by a branch pipe 14 and are connected to one end of the cylinder 42 of the pump control mechanism W by a pipe 15 having an adjustable needle valve 15 mounted therein.

Additional ports 55 and 5| in the cylinder 5| are connected by branch pipes 52 and I55 and these branch pipes are connected by a pipe 55 to the opposite end of the cylinder 42. The pipe 55 is similarly provided with an adjusting or needle valve 54.

Ports 55 and 51 in the cylinder 5| areconnected by additional pipes 55 and 55 to intermediate ports in the side 01. the cylinder 42. A pipe 55 branches 01! of the pipe 55 and leads to one end or the upper cylinder in the'speed control. and main dinerential valve mechanism V, while a pipe 5| branches oi! oi the pipe 55 and leads to the opposite end or the same upper cylinder in the valve mechanism V.

Additional branch pipes 52 and 55 lead oiT of the pipes 55 and 55 and are provided with adiusting or needle valves 54 and 55. The pipes 52 and 55 are joined to a common pipe 55 which connects to an opening at the lower side of the casing 35 01. the pump P. A corresponding opening at the upper side of the casing is connected by a pipe 51 to a pipe 55, which in turn is connected to the discharge or surge pipe 55 oi! the storage tank S.

Pilot pump and control connections The pipe 55 has an additional connection I55 to the tank S and also has a connection |5| to the under side of the casing of the pilot pump P. An additional connection I52 leads to the left hand end of the control cylinder I55 tor the constant pressure or pilot pump P'. The opposite end of the cylinder I55 is connected by a pipe I54 to the discharge pipe 55 ot the pump P.

A pipe I55 leads from the casing to the intake of the pump P, so that the oil supply oi the pump P is drawn from the tank S through the branch pipe I55, pipe 55 and branchpipe IN. The latter pipe delivers the oil to the lower part of the casing of the pump P' through which casing the oil flows to the pipe I55, by which the oil is dellveredto the intake 01', the pump P. The discharge of the pump P is delivered through the pipe 55 to the reversing valve mechanism V.

A piston H5 is slidable in the cylinder I53 and isconnected-by a rod III to a rack ||2, engaging a pinion 3 adapted to rock the output control cradle II 4 of the pilot pump P.

A spring I I5 acts against a collar I6 on the rod ill to move the piston 5 to the right in Fig. 2, or in a direction to increase the discharge or the pump P. A portion of the oil discharged from the pump P is delivered through the pipes 55 and I54 to the cylinder I55 and tends to move the piston M5 to the left or in a direction to decrease the discharge or the pump.

By suitably selecting or adjusting the spring 5, the pressure of the oil against the piston I I5 will balance the pressure of the spring 5 at a predetermined discharge pressure and this predetermined pressure will be continuously maintained by the pump P. If oil is discharg d through the pipe 55 in sumcient quantity to cause a drop in pressure, the spring II5 will overcome the pressure on the piston I I0 and will move the rack H2 in a direction to increase the discharge of the pump, thus bringing the pressure back to the predetermined normal.

Speed control and main diflerential valve mecha- 9| previously described I nism The speed control and main differential valve mechanism V comprises a casing I20 having an upper cylinder I2I and a lower cylinder I22. Three pistons I23, I24 and I25 are mounted in spaced relation on a piston rod I25 in the upper cylinder I2I, and two pistons I21 and I28 are similarly mounted in spaced relation on a piston rod I29 slidable in bearings at the ends of the lower cylinder I22 and connected for manual operation by a hand lever I30 (Fig. 1).

The rod I29 is also provided with a slightly enlarged portion providing a shoulder I3I which limits movement of the rod and pistons to the left in Fig. 2.

The pipe 54 connects the space H (Fig. 2) of the cylinder I3 to a port I33 which opens into both the upper and lower cylinders I2I and I 22. Similarly, the pipe 45 connects with a port I34, also opening into both cylinders, and a pipe I36 is connected at one end through the pipe 99 to the storage tank S and at its lower end through branch connections I31 and I38 to ports in the upper cylinder I2I.

The branch pipe 50 previously described also connects the upper pump discharge pipe 44 to an additional port in the upper cylinder I2I.

When the rod I29 and pistons I21 and I28 are in the position shown in Fig. 2, the piston I4 and table T wil be moved at relatively slow speed, as the discharge of the pump P will be delivered through the pipe 44 to the cylinder space I8, while the annular space H at the opposite end of the cylinder will be connected through the pipe 54, ports I33 and I34 and pipe 45 to the intake of the pump P.

As the oil forced out of the cylinder space H is much less in amount than the oil forced into the cylinder space I8, additional oil is supplied to the pump P from the storage tank S through the pipes 99 and I36, branch pipe I38 and pipe 45. The piston I4 is thus moved at the rate at which the full discharge of the pump will fill the cylinder space I5.

For high speed operation, (Fig. 4) the handle I30 is shifted to move the valve rod I29 and pistons I21 and I28 to their left hand limit of travel, thus connecting the pipe 54 through the ports I33 and I35 to the upper cylinder I2I and thence through the branch pipe 50 to the discharge pipe 44 of the main pump P.

In this case, the oil discharged from the annular cylinder space I I is by-passed around to the cylinder space I6 and it is only necessary for the pump P to supply oil equivalent to the difference in volume between the space H and the space I6. Consequently a given amount of oil delivered by the pump to the space I5, being used in addition to that by-passed around the piston I4, will produce substantially more rapid travel of the piston I4 and table T than when the oil is not by-passed.

During a high speed cutting stroke, no part of the oil discharged from the cylinder space H will return to the pump P and the oil supply of the pump must be obtained through the pipes 89 and I38, branch plpeI38, upper cylinder III and pipe 8.

Return stroke The position of the differential valve in the a upper cylinder I2I of the valve mechanism V is determined by the application of pressure at the ends of the valve through the pipes 94 and During the operative stroke, pressure will be applied through the pipe 9I, as indicated in Fig. 2, maintaining the upper piston valve in its right hand position, but on the return stroke pressure will be applied through the pipe 90, as indicated in Fig. 3, forcing the upper piston valve to the left.

This movement of theupper or differentialvalve is timed to take place when the piston 4I of the reversing valve mechanism W is Just passing neutral or mid-position, at which time the pump discharge is substantially zero. The rack 38 and gear 38 are in such mechanical relation to the piston 4I that when the piston is in mid-position, the cradle 34 is in neutral or no-discharge position as shown in Fig. 6. As soon as the piston 4| moves beyond mid-position in either direction, one of the pipes 88 or 89 is uncovered and the valve in the upper cylinder I2I is shifted before substantial movement of the cradle 34 from neutral position can occur. This is an ex'- tremely important feature of our invention, as serious results might be obtained if the differential valve was shifted while the pump was discharging in either direction.

The parts are shown in Fig. 3 as positioned for the return stroke after a high speed cutting stroke. Under these conditions, the pump P discharges through the pipe 45, upper part of port I34, port I 33 and the pipe 54 to the right hand end of the cylinder I3, while the left hand end. of the cylinder is directly connected through the pipe 44 to the intake of the pump P.

As the volume discharged from the cylinder I3 through the pipe 44 is greater than the volume supplied to the cylinder through the pipe 54, the surplus oil is delivered through the branch pipe 50, upper cylinder I2I to the branch pipe I31, and thence through the pipes I35 and 93 to the storage tank S.

The opposite ends of the lower cylinder I 22 are connected through passages I40 to ports in the upper cylinder which are connected through the branch pipes I31 and I38 to the storage tank. This permits out-flow of oil at the ends of the cylinder as the lower piston valve is shifted.

The operation of the valve mechanism for a return after a slow speed stroke is not shown in the drawings but is substantially identical with the operation after a high speed stroke, the only difference being that the path of flow of liquid from the pipe 45 to the pipe 54 is directly through the upper and lower parts of the port I34, instead of through the ports I34 and I33 successively as previously described. No difference in ultimate result is produced.

Tool feeding mechanism with adjustable stops I45 and I46, engaging opposite sides of a fixed abutment I41.

At its lower end, the piston rod I44 may be connected in any convenient manner to operate the cross feed of the cutting tool.

In Fig. 2 we have indicated these connections as comprising a ratchet wheel I46 mounted on a cross feed shaft I49 and engaged by a double pawl Ill mounted on the lower end of the valve rod I44. The pawl I50 may be set to operatively engage the ratchet I46 either on the upward stroke or on the downward stroke, as may be desired, and may be provided with any suitable spring devices for holding it in yielding engagement with the ratchet in either position.

A pipe I52 connects the lower end of the cylinder I42 to a control cylinder I54 at about the middle of its length. The upper end of the cylinder I42 is connected by a branch pipe I55 to the upper endof the cylinder I54, and by a branch pipe I56 to a lower point in the cylinder I54.

Pistons I51, I58 and I56 are mounted in spaced relation on a piston rod. I60 extending upward through the cylinder I54 and manually adjustable to high, low or intermediate positions.

A pipe I62 is connected at one end to the discharge pipe 44 of the pump P and at the other end to a port in the side of the cylinder I54 between the ports for the pipes I52 and I55. A pipe I63 is similarly connected at one end to the discharge pipe 45 of the pump P and at the other end to a port in the cylinder I54 between the ports for the pipes I52 and I56.

The cross feeding mechanism is shown in Fig. 2 in the position for feeding just prior to the beginning of the cutting stroke. The valve rod I60 is in its raised position, and oil under pressure is delivered from the pump discharge pipe 44 through pipe I62, control cylinder I54, and pipe I52 to the lower end of the cylinder I42, giving the piston I43 an upward feeding stroke as the pressure is built up in the discharge pipe 44 as the pump P is reversed and just prior to the working stroke.

When the pump P is again reversed at the end of the cutting stroke, pressure in the pipe 45 will be transmitted through the pipe I63, cylinder I54, and pipes I56 and I55 to the upper end of the cylinder I42, thus forcing the piston I43 downward and giving the pawl I50 an idleor return movement. The amount of feed may be controlled by the setting of the stop nuts I45 and I46.

If the valve rod I60 is moved to its middle or neutral position, the pistons I51 and I56 close the port openings of the pipes I62 and I63, and the cross feed is thus rendered inoperative.

If the valve rod I60 is moved to its lowest position, oil under pressure will be delivered from the pipe I62 through the pipe I55 to the upper end of the cylinder I42 to effect an idle return movement just prior to the beginning of the cutting stroke, and will be delivered from the pipe I63 through the pipe I52 to the lower end of the cylinder I42 to effect a feeding movement just prior to the beginning of the return stroke. Consequently, feed will take place at the beginning of the return stroke rather than at the beginning of the cutting stroke.

By reversing the setting of the pawl I50, cross feed in the opposite direction may be attained.

Tool lifting device It is desirable under some conditions that the cutting tool K be lifted from the work during the return stroke, so that the edge of the tool will not be dulled or broken by being dragged over the surface of the work. For this purpose we provide a small cylinder I10 (Fig. 2) mounted in the tool holder or clapper HI and having a piston I12 mounted on a plunger I13 which projects through the outer end of the cylinder I10 and engages the cross head I14.

A pipe I15 connects the cylinder I10 to the pipe I63 which in turn is connected to the pipe 45 to which oil is delivered under pressure during the return movement of the table.

Consequently, whenever pressure is applied in the pipes 45 and I63, pressure will also be applied through the pipe I15 to the cylinder I10, forcing the piston I12 into the cylinder against the pressure of a spring I16.

As the cross head I 14 cannot yield, the tool holder or clapper I" is thereby swung outward, raising tool K away from the table T during the return stroke.v

A control valve I16 provides for adjustment of the rate of movement of the tool holder HI and a by-pass I11 with a check valve I15 permits quick seating of the tool holder before the cutting stroke.

Operation Having described the details of construction of our improved mechanism, the method of operation is as follows:

' The mechanism is first set for a fast or slow speed cutting stroke by manual adjustment of the handle I30, by which the speed control valve in the lower cylinder I22 of the valve mechanism V is adjusted. The feed control valve rod I60 is also set to effect the intermittent feed just prior to the return stroke or just prior to the cutting stroke, as may be desired under existing operating conditions.

Disregarding for the present the devices by which deceleration and acceleration are controlled, we will assume that the reversing valve V is in the'position shown at Fig. 2, with the table T moving to the right. It will be seen that oil at constant pressure will be delivered by the pilot pump P through the pipes 66 to the reversing valve cylinder 6I and thence through the pipes 14 and 15 to the right hand end of the control cylinder 42, forcing the piston 4i to its left hand limit of travel and adjusting the main pump P for maximum predetermined discharge through the pipe 44. i

This effects a working stroke of the table T at high or low speed, in accordance with the setting of the valve rod I26 by handle I30. At the same time, the pipe 33 from the left hand end of the control cylinder 42 is connected through the cylinder 6i and pipe 69 to the storage tank S. At the end of the cutting stroke, the reversing valve V is shifted to the position shown in Fig. 3, so that oil under pressure is delivered from the pilot pump P through the pipe 66, cylinder 6i and pipe 33 to the left hand end of the control cylinder 42.

This moves the piston 4I to the right and reverses the discharge of the pump P, so that the pump now discharges through the pipe 45 to the right hand end of the cylinder I3, causing a return movement of the piston I4 and table T. At the same time, the pipe 15 from the right hand end of the cylinder 42 is connected through the cylinder 6i and pipe 69 to the storage tank S.

It will be noted that whenever oil is delivered to either end of the cylinder I3 by the pump P,

this oil flows freely past the check valve 41 or 58, but that when oil flows from the cylinder l8 to the pump P. this flow is resisted by the check valves and must take place through the by-pass 48 or 98, such flow being regulated by the ad- Justing valves 49 and 51. Consequently, any desired back pressure can bemaintained on the piston 14, so as to induce a smooth and even motion in either direction.

Operation of pump control mechanism W A very important part of our invention relates to the operation of the mechanism V, which effects the reversal of the pump P and consequently the deceleration and acceleration ofthe table T.

During the cutting stroke, the piston 4| of the control mechanism W is in the left hand position shown in Fig. 2, and the reversing valve mechanism V is also. in the position shown in Fig. 2.

At the end of the cutting stroke, the arm 2| is engaged by one of the dogs 28 and the reversing valve is moved to the right toward the position shown in Fig. 3. As the reversing valve starts to move, oil under pressure is first admitted through the branch pipe I89 and pipe 88 to the left hand end of the cylinder 42.

As the port for the pipe 88 in the cylinder 42 is closed by the piston 4|, the full oil pressure is applied to the left hand side of the piston 4| but the rate of flow to the cylinder 42 is controlled by the setting of the regulating valve 84.

The right hand end of the cylinder 42 is still connected to the oil supply through the pipe l8 and branch pipe 14, but the port to the pipe 89 is open so that oil can flow past the regulating valve 95 to the pipe 98 and thence through the casing of the pump P to the storage tank S. Consequently the oil pressure in the right hand end of the cylinder 42 is somewhat reduced and the piston 4| begins to move toward the. right, the rate of movement being controlled by the setting of the valves 84, I8 and 95.

Pressure is maintained in the pipe 9| and the piston valve in the upper cylinder |2| of the valve mechanism V' remains in the position shown in Fig. 2, with the pipe 99 connected to the return.

Meanwhile, the reversing valve continues its travel to the right until the port 81 for the pipe 89 is uncovered, thus connecting the pipes 89 and 98 to the return pipe 89, which connects directly to the storage tank S and allows the oil to return without passing through the regulating valve 95.

In the meantime, the piston 4| has been moving toward the right. During the first part of its stroke this movement was due to the net difference in pressures on the two sides of the piston 4| and was controlled by the three valves 8t, 95 and it.

By the time the pipe 89 was connected to the return pipe 69, the piston 4| had been moved far enough to shut off the connection to the pipe 89 from the cylinder 42.

The pressure in the pipe 9| and the left hand end of the cylinder |2| was thus relieved, and a slight dwell of the reversing mechanism of the pump P occurs, as there is balanced pressure on the piston ti.

A slight continued movement of the reversing valve causes the piston 82 to shut off the oil supply to the branch pipe M and a slight further movement brings the valve to the final position with the pipe 18 connected to the return pipe 89,

-as shown inTig. 3.

During the continuedmovement of the piston 4| to the right, the oil ejected from the cylinder 42 is all forced to escape through the pipe 15 and is controlled by the valve 16. 2

Furthermore during the latter part of the stroke of the piston 4|, the connection from the left hand end of the cylinder to the pipe 88 is opened. thus reducing the effective pressure to move the piston 4|, as a portion of the oil under pressure escapes past the valve 94 and through the pipe 92 to the casing of the pump P and thence to the storage tank.

when the pipe 88 is uncovered, oil under pressure acts through the pipe 9|! to move the piston valve in the cylinder |2| to the left, reversing the connections to between the pump P and the cylinder l3. This reverse movement of the valve in the cylinder |2| takes place when the pump a P is in neutral position and there is no discharge found that a heavy planer table or similar object can be decelerated or brought to rest more quickly than it can be accelerated or broiight up to speed in the opposite direction.

The branch pipes 92 and 93 and the regulating valves 94 and 95, taken in connection with the adjusting valves 16 and 84, permit us to'cary the rate of movement of the piston 4| during different parts of its travel and to cause the pump P to be brought to neutral and to be rendered operative in the reverse direction in any desired time intervals.

Suitable provision is made for determining the setting 01' the pump P for discharge in each direction. In Fig. 2 we have indicated adjustable stop screws |8| and I82 positioned for engagement by a lug or projection I83 on the rack 38. By adjusting the screws |8| or I82, the limit of movement of the rack in each direction may be determined, which in tuiyn will determine the extreme positions of the rocking cradle 33 and will thus determine the rates of discharge of the pump P.

It will be evident that this rate of discharge may be independently adjusted for each direction of operation, so that the speed of the table T during its working stroke and also during its return stroke may be independently determined. Under ordinary conditions, the return stroke will be made at substantially higher speed than the cutting stroke.

The operation of our hydraulic operating mechanism may be conveniently stopped by manually moving the reversing valve V to its middle or neutral position, which causes the piston 4| to move to the middle or neutral position shown in Fig. 6, in which it will be seen that the pressures are balanced on the two sides of the piston 4| and that the pipes 88 and 89 are both closed by the piston 4|. After being moved to this position, the piston 4| will remain indefinitely in neutral position, as any movement of the piston in either direction would partially uncover one of the pipes 88 or 89, thus reducing the pressure on the side from which movement had occurred, so that a reverse or return movement to-neutral position would immediately take place. Consequently the planer or other machine tool can be manually stopped in any position by moving the reversing valve V to mid-position, and will remain at rest until the valve V is manually moved to one or the other of its operating positions.

Having thus described our invention and the advantages thereof, we do not wish to be limited to the details herein disclosed, otherwise than as set forth in the claims, but what we claim is:-

l. Hydraulic actuating mechanism for a member connected to be reciprocated by relative movement of a cylinder and piston, said mechanism comprising a reversible discharge pump having two flow openings, means to continuously connect one opening to one end of said cylinder, means to connect the other opening to the other end 01' said cylinder, and means to effect discharge of said pump through one of said flow openings to cause travel of said reciprocated member in one direction and through the other flow opening to cause travel of said reciprocated member in the other direction, said latter means being controlled by said reciprocated member as it approaches a limit of travel and comprising pump-reversing mechanism, a cylinder and piston connected to move said mechanism, and a plurality of separate devices acting successively and automatically to determine difierent rates of movement of said latter piston in difierent portions 01' its stroke during a single pump reversal.

2. Hydraulic actuating mechanism for a member connected to be reciprocated by relative movement of a cylinder andpiston, said mechanism comprising a reversible discharge pump having two flow openings, means to continuously connect one opening to one end 01' said cylinder, means to .connect the other opening to the other end or said cylinder, means to effect discharge or said Pump through one 0! said flow openings to cause travel of said reciprocated member in one direction and through the other flow opening to cause travel or said reciprocated member in the other direction, said latter means being controlled by said reciprocated member as it approaches a limit of travel and including devices efiective to vary and control the rate of deceleration and the rate of acceleration of said reciprocated member during a single reversal thereof and to control each rate of change independent of the other rate.

3. Hydraulic actuating mechanism for a reciprocated member comprising a variable delivery reversible discharge pump and devices controlled irom said member for varying and reversing the discharge of said pump, said devices including a control cylinder and piston connected to reverse said pump, and means by which the.

livery reversible discharge pump, and devices con-- trolled irom said member for varying and reversing the discharge oi said pump, said devices including a control cylinder and piston connected to reverse said pump and meanslto variably control the rate of movement of said control piston in different parts of its stroke and 'by which a predetermined dwell at the middle portion 01' the stroke may be efl'ected during said pump reversal.

5. Hydraulic actuating mechanism for a reciprocated member provided with a cylinder and piston, one of which is connected to said mem- I ber, said mechanism comprising a variable delivery reversible discharge pump having discharge openings one of'which is' continuously connected to one end of said cylinder and speed control valve mechanism through which the other of said discharge openings is connected to the opposite end of saidcylinder, means controlled from said reciprocated member and effective to reverse the direction of discharge of said pump at each limit of travel of said reciprocated member, and means to separately control the rate of deceleration and the rate oi acceleration of said reciprocated member during a single pump reversal, whereby either rate of change may be independently varied during said single reversal.

6. Hydraulic actuating mechanism for a member connected to be reciprocated by relative movement of a cylinder and piston, said mechanism comprising a reversible discharge pump, means to reverse the direction of discharge 01' said pump, a storage for excess liquid, a by-pass connection from one end of said cylinder to said storage, and automatic means comprising a pressure operated valve, said latter means being ef- Iective to open said by-pass connection 'at one limit of travel of said piston and when the pump is substantially in zero discharge position.

DONALD H. WEST.

KENNETH C. MONROE.

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