US2630848A - Hydraulic log barking apparatus - Google Patents

Description

M. L. EDWARDS HYDRAULIC LOG 'BARKING APPARATUS 5 SheetsfSneeo l Filed July 5. 1947 .Z o j. l fg' Z zo l March l0, 1953 -muLE-s Loweu. e-Dwmzns /4 rrR/ves/E March 10, 1953 M. L. EDWARDS HYDRAULIC LOG BARKING APPARATUS 5 Sheets-Sheet 2 Filed July 5, 1947 YNLE'S LOWELL EDWARDS March 10, 1953 M. EDWARDS 2,630,348

HYDRAULIC LOG BARKING APPARATUS Filed July 5, 1947 5 Sheets-Sheet 5 #vz/5 /v TUR Mugs LOWELL EDWARDS E @LJ/M March 10, 1953 M. l.. EDWARDS v 2,530,848

` HYDRAULIC LOG BARKING APPARATUS Filed July 5, 1947 5 Sheets-Sheet 4 E CMM/M March 10, 1953 M. EDWARDS 2,630,848

HYDRAULIC LOG BARKING APPARATUS Filed July 5, 1947 5 Sheets-Sheet 5 //\//5 TDI- MILES LOWELL EDWARD!) /47- TDH/v gv and consequently prime mover energy.

Patented Mar. l0, 195.?

iJNlTED STATES v A"IENT OFFICE HYDRAULIC LOG BARKING APPARATUS Application July 5, 1947, Serial No. 759,245

(Cl. 144A-208) 11 Claims.

This invention relates to the barking of wood, and has particular reference to improvements in the application of hydraulic jets to a log surface to remove the bark therefrom.

The increasing cost of wood and the expanding utilization of bark products makes it ever more desirable to remove the bark cle-anly from the log in a manner that will not waste or damage the wood and will not include wood in the removed bark. Conventional rossing machines are not capable of removing all the bark and, at the same time, maintaining a clean separation of the bark from the wood, because on irregular logs the action of cutting tools cannot be stopped at the cambium layer. Hydraulic methods are inherently adapted to effect a clean removal of the bark without inclusion of wood chips and slivers, but have been subject to numerous disadvantages in the manners practiced in the prior art.

A considerable amount of power is required to maintain the necessary velocity head in a hydraulic jet to remove thick and tenacious bark from large logs. Such a high velocity stream cannot be turned olf and on at frequent intervals, but must be left running in short periods of nonuse because the valves cannot be closed and opened quickly and heavy pumping equipment cannot be started quickly. In addition to this limitation it has been found difcult to maneuver the water jet and a large log to remove all the bark and to shift quickly from one log to another without wasting a great amount of water, When a jet is moved haphazardly over the log surface some areas receive longer treatment than others, causing a non-uniform removal of bark and a waste of water, and then more water is wasted in moving over barked areas to give further treatment to remaining islands of bark. The small area covered by a jet makes it impractical, if not impossible, to eect a movement, or feed, of the log relative to a stationary jet to apply the jet successfully in a geometrical pattern to give uniform treatment to all points on the surface of a large, irregular log. Even slight irregularities in the log surface are sucient to cause gaps and overlaps in the barking action resulting in spotty bark removal which makes conventional mechanical feed mechanisms inoperative for hydraulic log barking unless a large percentage of the water is wasted in excessive overlaps. The conventional hydraulic barking operation, therefore, frequently effects a compromise between complete bark removal and excessive wastage of water and time, with the result that patches of bark -may be left on the log.

In general, the object of the present invention is to provide improvements in the hydraulic barking of wood to make the barking process fast, thorough and economical of water. A primary object is to provide a method of applying one or more jets of water to a moving wood surface in a dennite systematic pattern to subject the entire bark area of the wood progressivelyto substantially uniform jet action without overlapping of different areas of treatment and without leaving any untreated areas. Further objects are to provide a method of application of the hydraulic jets to the bark surface on a log in which one or more jets are oscillated through a predetermined zone of action and the log is moved relatively to the jets to extend the zone of action over the surface of the log, to provide a method wherein one or more hydraulic jets are oscillated longitudinally of the log in coordination with a turning and feeding of the log relative to the jets to remove the bark progressively in a spiral pattern, to provide a method of feeding logs successively through a barking chamber to remove the bark from any number of logs in a continuous operation without wasting water in intervals between successive logs, and to provide novel apparatus forl performing the steps of the method.

In applying the present method to logs, the logs to 'oe barked are fed longitudinally and rotated through a zone of jet action in a barking chamber. The logs are fed one after another in this manner with relatively little gap therebetween to reduce the loss of time and Water in the spaces between successive logs. In the zone of jet action there are disposed one or more nozzles directed against the log surface at the optimum angle for maximum bark removal. If more than one nozzle is employed, the several nozzles are disposed in a plane preferably at a small angle with a radial plane through the log, and the nozzles are oscillated in their common plane so as to move back and forth lengthwise of the log. The angles of oscillation or traverse of the nozzles are adjusted to produce an elongated zone or" action having a length equal to the sum of the lengths of the lines of action of the individual nozzles.

The jets from such nozzles are preferably attened in a direction perpendicular to the axis of the log and perpendicular to the common plane of oscillation. Thus, when the nozzles oscillate, the jets move in directions at right anglesfto the planes of the jets to sweep a certain bark area. The log feed in rotation is adjusted so that the area swept by the jets includes new bark surface at each oscillation. Where a single sweep of the Jet is suicient to cleanly remove the bark, the

rotation of the log may be such as to subject an entire new area of bark to jet action at each sweep, but, obviously, the log feed may be adjusted to produce any amount of overlap necessary for complete bark removal. The longitudinal feed rate of the log is coordinated with its rotational movement so that the bark is completely removed in a spiral path in one continuous operation without subjecting any part of the log to secondary treatment.

The method of the invention is best understood with reference to the diagrams and apparatus illustrated in the accompanying drawings, although it is to be understood that other equipment may be devised to perform the steps of the method.

In the drawings:

Figure 1 illustrates diagramma-tically the path of motion of a single oscillating hydraulic jet on 4a developed log surface after-the log has made approximately one and one-half revolutions under the action-of vthe jet accordingT to the meth- Vod of the invention;

Figure 2 is a diagram on an enlarged scale showing 'bark areas swept on successive oscillations and the pattern of bark removal produced by a single jet having a path of movement on an advancing and rotating log surface as shown in Figure 1;

Figure 3 is a view similar to Figure l, showing the center line paths of movements of a pair of jets oscillating in opposite directions in a common plane;

Figure 4 illustrates on an enlarged scale the swept areas and bark removal pattern produced by the twin jet arrangement having the movements shown in Figure 3;

Figure 5 is a side elevation view of a log showing the pattern of bark removal either by a single jet, as shown in Figures 1 and 2, or by a series of jets oscillating in a plane, as shown in Figures '3 and 4;

Figure 6 is a plan view of a log barking plant equipped to carry out the present method of hydraulic barking;

vFigure 7 is a side elevational view of the plant .shown in Figure 6;

`VDiagmmmatie explanation of the method In Figure 1' the numeral IG designates a developed surface portion of a log undergoing treat- .ment in a barking operation according to the 'method of the invention. Let it be assumed, for

of reference and conventional representation, that the log from which the developed =surface if! is taken is being fedlongitudinally from right to left through a zoneof action of a f single oscillating hydraulic jet, and that the logis caused to rotate so asto igradually move J'the :leveloped surface downwardly withA respect to'the oscillatingjet, kas viewed inFigure 1. The

numeral H on the left end of the developed surface then designates a bare wood surface from which the bark has just been removed by passage through the zone of action of the barking jet, and the numeral I2 on the right end of the developed surface represents a bark surface which is approaching said zone of action. The broken zigzag line i3 traces the path of movement of the single oscillating jet relative to the log surface as the latter advances and rotates relative to the jet. It is understood that the log is advanced and rotated relatively slowly and that the hydraulic jet is oscillated relatively fast in a direction longitudinally of the log.

Because of the rotation of the log, the center Aof impact of the jet does not retrace its path on successive oscillations, but advances in the zigzag patterns shown, spirally around the log to subject all the bark on the log progressively to the action of the jet. Thus the jet follows vthe path of the arrows in the line I3 from a point I4 to a point l5 in one complete rotation of the log. Since the surface l@ is a developed surface, the point i6 coincides with the point l5 on the log, and in the next half revolution of the log the jet traces the zigzag path indicated from the point I6 to the point l'l. As the log continues to rotate and advance from right to left, thevzigzag path IS continues in the same manner and the unbarked surface i2 is progressively subjected to the same action. The longitudinal feed rate of the log is coordinated with the amplitude of lthe jet oscillation so that the longitudinal advance in each revolution is approximately equal to such amplitude whereby the zone of action between the points l@ and I'llies immediately alongside the zone of action between the points i0., and I5, and so on in successive revolutions.

When the jet is flattened in a vertical plane, the zone of action takes the form shown on a larger scale in Figure 2. The line 2i) represents the position and width, or effective vertical height, of the flat stream where it impinges upon the log surface at the left hand limit of movement of the jet on a particular oscillation. The line 2i indicates the position of the stream on Ythe bark at the limit of its nekt movement in a right hand direction. From the line 2l the stream then moves to the left to the line 22, and then back tothe right to the line 23, and so on, to sweep a parallelogram area in each oscillating movement, as shown. 'The horizontal distance between the two vertical llines 2B and 22 represents the amount of longitudinal movement of the log during onercycle of oscillation of the jet, and the vertical displacement of these two lines indicates the amount of rotational movement of the log in this period of time. It will be observed that there is a substantially complete overlap in the right andleft hand movements ofthe jet, so that the jet is caused to pass twice over each point on the log surface as the jet oscillates and the log revolves. The log feed may be adjusted to provide more or less overlap, as the bark condition may require. For example, the bark may be removed cleanly from some logs without necessity for the jet to impinge upon every small portion of the bark surface, while on other logs several-passes may be necessary on each part of .the bark suraceto remove the bark cleanly from the wood. Also, when different nozzles are used, the log feed may beadjusted to obtain the most-emcient barking action.

Itis desirable in practice to'use two hydraulic jets synchronously oscillating in side by side'relation. Such an arrangement not only extends the zone of barking action to substantially double the rate of bark removal, but also enables the vibrating forces to be balanced in the nozzle oscillating mechanism. The center line paths of movements of dual oscillating jets are shown in Figure 3, wherein the broken line I3 traces the path of motion of one of the jets and the line 13a traces the path of the other jet. It is observed in this diagram that the jets are caused to move always in opposite directions in a common plane of action, and that at the end of each cycle of oscillation they impinge upon the log at closely adjacent points. The two jets thus describe zigzag spiral paths around the log to extend the zone of action over untreated bark immediately alongside the zone of action in the preceding revolution of the log. The zones of action of the two jets thereby proceed around the log in the manner of a double spiral thread having a lead equal to twice the amplitude of vibration of one of the jets. Preferably, the hydraulic pressure and log feed rates are adjusted so that overlapping with previous zones of action does not occur, but, of course, any amount of longitudinal overlapping may be obtained if desired by slowing up the longitudinal feed rate of the log, just as circumferential overlapping may be obtained Vby slowing up the rotational feed rate of the log.

When the longitudinal and rotational feed rates of the log are adjusted to produce relative center line paths of movement of the two jets as shown in Figure 3, the zones of action covered by the-se two jets are represented by the adjoining continuous parallelogram patterns 24 and 25 shown on an enlarged scale in Figure 4. In each oscillating movement each of the jets sweeps through a parallelograrn area of action, and the two zones comprising these successive parallelogram areas interit in the manner shown to produce a total zone of action taking the general form of a spiral band around the log similar to that produced by the single jet in Figure 2.

The barking action produced by the spiral advance of the zone of action around the log is illustrated in Figure 5. The numeral Il designates bare wood surface from which the bark has already been removed by the longitudinal feeding lmovement of the log from right to left, and the numeral l 2 designates untreated bark which has not yet passed through the zone of hydraulic action. The spiral edge of bark 2S represents a succession of the vertical lines 2|, 23 etc., marking the right hand edge of the zone of action. The bark edge 2 represents the advancing end of the zone of action which may be produced by a single jet or by a plurality of jets in the manner described. More than two jets may be employed if desired. Thus the bark is removed in a spiral path around the log in which substantially the Same amount of energy is applied to every point on the log to remove the bark cleanly with a minimum amount of water in a minimum time for a given power consumption in the hydraulic system.

In Figures 1 to 5 it is apparent that the log is twisted and advanced in the manner of a bolt with a left hand thread. It will be observed that an important purpose accomplished by the fiattening and oscillation of the jet or jets is to extend the zone of action to cover sufficient area so that a mechanical feeding mechanism can be employed effectively without a large percentage of overlap at the margins of the zone of action. Since a log surface is not truly cylindrical it is diicult to provide a ne and accurate feed,

especially in rotation, for use with a small jet. By flattening the jet in a vertical plane the feeding problem is simplified and more uniform surface coverage is assured. The directions of rotation and advance may of course be reversed without departing from the spirit of the invention.

The present method is also applicable to bark surfaces on saw mill slabs and the like, in which case it may be preferable not to move the slabs vvertically in conjunction with the horizontal feed, but to alternately elevate and depress the plane of the jets in order to cover the more limited area of the slab. It is, therefore, to be understood that the feed motion to produce the bark removal patterns described hereinabove is merely relative and does not necessarily require the same absolute movements of the Wood longitudinally and rotatively that have been described as suitable for log sections.

The barking plant A hydraulic barking plant for carrying out the method of the invention is illustrated in Figures 6 and 7. During the barking treatment the logs are supported for longitudinal and rotational movements on pairs of obliquely disposed power driven trunnion wheels 30. VA plurality of substantially horizontal conveyors 3l form a log deck upon which the logs to be barked may be placed side by side as they are received. A series of retractible stops 32 hold the logs on this deck until they are needed. The conveyors forming the log supporting surface of the log deck are power operated from time to time to move the logs sidewise until the outermost log is crowded against the stops 32. The numeral 33 designates a series of loading chains on lift skids which may comprise arms pivotally mounted for vertical movement on a horizontal shaft 3d which may also carry idler sprockets for the log deck conveyors 3l.

Suitable controls are provided for these Various mechanisms so that the stops 32 may be retracted to transfer a single log from the deck conveyors 3l Yto the lift skids 33, on which it is then moved outwardly to a position immediately above the pairs of trunnion wheels 30 while the lift skids are in a raised position as shown in broken lines in Figure 8. By then lowering the outer ends of the lift skids the log is deposited in the trough formed by the trunnion wheels. Pairs of retractible centering arms 35 mounted on central pivots 36 are provided to align the log with the pairs of trunnion wheels as the lift skids are lowered. After the log is deposited in this manner on the trunnion wheels, the lift skids are dropped out of the wayl as shown in full lines in Figure 8 so that the log rests solely upon the trunnion wheels. The centering arms may, if desired, be maintained in positions just out of engagement with the log to serve as guards against accidental displacement of the log from the trunnion wheels.

Rotation of the trunnion wheels serves to advance the log from right to left, as viewed in Figures 6 and 7, and to rotate the log in the manner of a bolt with a right hand thread. Means will hereinafter be described for adjusting the angles of the trunnion wheels to change the rate of longitudinal feed of the log in relation to its rate of rotation. As the log is advanced longitudinally on the trunnion wheels it gradually approaches the zone of action of hydraulic barking jets which are projected and oscillated through an elongated opening 38 in a shield 31 extending longitudinally beneath the under surface of the at their most effective distance from the bark surface. Moreover, the centering action of the trunnion wheels 3! insures that logs of al1 sizes will be centered in thesarne vertical plane to maintain the same angle between the bark surface and the plane of oscillation of the jets. The trunnion wheels 30 thereby establish a reference position for thatl portion cf the log surface which is being acted upon by the hydraulic jets, and so whether the logs be large or Small the Surface portions to be treated are brought into substantially the same reference positions for the most effective jet action.

A movable-shield B1 may be mounted between the zones of action of the two jets to be swung into a position to intercept or deflect one of the jets when the log surface is sufficiently remote to cause objectionable overlapping or conflict between the jets as they approach each other. This shield is shown in retracted position in Figure 9.

The nozzles are preferably designed to produce jets oi water which are iiattened parallel with Athe plane of the view in Figure 8 and perpendicular to the plane of the view in Figure 9 to sweep parallelogram areas of the log surface as shown in Figure 4. Other forms of nozzles and oscillating mechanism may be used, however, to practice the method of the invention.

Trunmon wheel construction The details of construction of the log Supporting trunnion wheels are best shown in Figure l0. Each trunnion wheel 3l! is carried by trunnions SU in a yoke member 9| which is mounted on a base 92 for rotation in a xed base member 93. A bearing member Se between these two members assumes the thrust and other loads imposed by the weight of the log. A lever arm extension 95 on the rotatable base 92 provides for adjusting the angle of lead of the trunnion wheel, and the levers 95 on the several trunnion wheel assemblies are interconnected by links 96 so that the lead will be the same on all the trunnion wheels and so that they may all be shifted in unison by a single adjusting mechanism.

The links 9E extend through the length of the barking plant as shown in Fig. 6, and are pivotally connected to the opposite ends of a beam 9'! mounted on a central pivot 93 so that when one of the links is moved in one direction the other link will move an equal amount in the opposite direction. The links are thus shifted to provide the desired angle of lead in trunnion wheels 3B, as shown diagrammatioally in Fig. 6.

Each trunnion wheel carries a bevel ring gear l@ driven by a bevel pinion IBI on one end of a shaft |62. The other end of the shaft |02 carries an overriding clutch |83 by which the shaft is driven from a ring gear |04 which is in turn driven by a pinion |05 on one end of a shaft IHS. The shaft |86 is concentric with the bearing 94 and carries on its outer end a bevel gear lill driven by a bevel pinion |08 on a shaft iii) extending the length of the barking plant shown in Figure 6. By means of similar bevel gear drives a pair of the shafts l il) arranged as shown in Figure 8 are adapted to drive all the trunnion wheels at the same speed. The two shafts H0 are in turn driven by chain and sprocket wheel drives ||3 (Figure 6) from a single prime mover H4 at variable speeds under the control of the operator in the operators room. The numeral I I designates a splash guard to enclose the gears |00 and |01 and one of the trunnion bearings.

'I'he other trunnion bearing is protected by packing H2.

The overriding clutch may be of any approved form, a specific construction being illustrated in Figure 12. In this construction the shaft |02 carries a member ||5 having a plurality of balls H6 or other wedging members disposed in individual recesses HT enclosed by a hub iid on the gear lil. The wedging members H6 are spring pressed into wedging engagement between sloping walls of the recesses and the hub B so that when the latter is rotated in a clockwise direction a positive driving connection is established between the ring gear |04 and the shaft |02. The shaft |02 is always free to rotate faster than the hub i8, because in such case the wedging members i |6 are pushed back into the deeper portions of the recesses Il to allow relative motion in one direction between the member H5 and the hub H8. Inasmuch as the logs carried by the trunnion wheels are not truly cylindrical, the different surface speeds on different parts of the log tend to drive certain of the trunnion wheels faster than they are driven by their'prime mover, and the present overriding clutch mechanism accommodates this difference in relative surface velocities of the log without causing the log to slip on the trunnion wheels or climb out of the trough between the trunnion wheels.

The trunnion wheels are provided with teeth |2, as shown in Figure 1l, to engage the log at each point of support and cause it to rotate with the trunnion wheels. These teeth inflict relatively little damage on a log, even after it has been barked, because of the uniformity of the angle of lead in all the trunnion wheels and the overriding clutches permitting the trunnion wheels to be driven by the log when the surface speed of any part of the log exceeds the peripheral driven speed of the trunnion wheels.

The two hold down wheels 6|! are preferably positioned immediately over the two pairs of trunnion wheels in the barking chamber. If desired, these wheels may be mounted to caster on the log to follow the angle of lead set into the trunnion wheels. In Figure 8 the hold down wheel 60 is shown mounted on a vertically movable member |25 which may be raised on a guide |26 to pass a new log thereunder and then lowered to bear on the log with a force sufficient to counteract the lifting force of the barking jets. The hold down force applied to the wheel 6U is preferably exerted by some resilient means, such as compressed air in a cylinder, to allow the wheel to rise and fall over the irregularities of the rotating log. Such a resilient force may be applied in any convenient manner, such as by a piston rod |21, and the member |25 may be vertically slidable or pivotally mounted to provide a su'icient range of vertical movement for the wheel 60.

It is to be understood that the method of the invention is not to be limited by the use of a particular apparatus, the present barking plant being shown and described merely for the purpose of illustration and not for the purpose of limiting the invention. The invention is to be limited only by the scope of the appended claims.

Having now described my invention and in what manner the same may be used, what I claim as new and desire to protect by Letters Patent is:

lf In 211 hydraulic 10g barking apparatus, a pair of nozzles mounted for oscillation in a commOn plane, a fluid cylinder and piston for oldin oscillating said nozzles, means for reversing said nozzles quickly at the end of each stroke to causesaid nozzles vto move at substantially constantspeed throughout each stroke, and a linkag interconnecting said piston and said nozzles 'and including means for moving said nozzles always in opposite directions in 'a manner `to redio'e lvilziration in the apparatus.

In hydraulic log barking apparatus, logholdihg means having a 'spiral feed movement, a nozzlemountcd ior'oscill'ation in a plane intersecting the longitudinal axislof the log-holding means, a balancing mass mounted for oscillation inf'said plane relative to said nozzle, power-operatedlfmeans'cperatively connected to said'no'zzle fo oscillatingsaid nozzle rapidly in said plane, the nozzle v`andbalarming mass being on opposite fsidesoi `said kpower-operated means, `'means for reversing saidnoz'zleduickly at theend'o'f each scillatory'movement tocaus'ethe nozzle to move v su'vbstantiallyconstant 'speed throughout each m mentnand @1J-mechanical Ylinkage intercon- `ting'y 'said nozzle, said power-operated means, and balancing vrria'ss *for Vmoving said nozzle and :mass {alwaysf;inc opposite directions ytov/'ard and away from each other'i'n said plane to reduce vibracin. In hydraulic log barking apparatus, lognpiging means having a spirarfeec movement, a rs't 't secting'ltlie longitudinal akis'o the log-holding means, ajseoon'd nozzle mounted oros'cilla'- t n ingsaid planerelativejtosaid first nozzle, far-operated means'operatively connected to zal@ in saidu'plane; means lforreversing said nozzles Quickly atthe end of each oscillatory movement to cause the nozzles to move' ali-substantially constant speed Vthroughout eachfm'fojement, and a mhaidai iiiuag interconnecting said nozzles and said power@ rate 'means te move said noz"- zles always opposite dirfectio'ns toward and away rom eachother in "said plane' to reduce vibration. h

hyclraulic log barking apparatus, log'- means having a spiral 4feed movement, a nozzle mgunted for lscillation'in'a plane interse tiiigfth'e longitudinal axis'o'f 'the logfh'old- 'ing means, a balancing mass mounted fr'o'scillation inl'said plane relative'to said nozzle, "poweroperated ineansloperatively connected to 'said nozzle fro'r 'oscillating said rioz'zlera'pidly in said plane', thenozzle and balancing mass'being on opposite "sides 'of l'said powerloper'ated means,

means for reversing said nozzleV quickly "at the end ofeach oscillatory movement to causethe nozzle to move at substantiallyvconstant speed throughout -each movementsaid reversing means including a valve mechanism and Step regelaars;l and a mechanical linkage interconnecting said nozzle, SaidY pover-Operated, means and balancing iria-@S for moving said'n'ozzle and mass always'in oplI Josite'directions' oward 'andfa'way yfrom 'each other in Lsaid plane to 'reduce vibration.

Y y5- in an. hydra lic. beperking encamina. a pair Qf. ezzlesmo .ated for @Seller-01,1' ma 99mrnon plane, a duid cylinderand piston Viorroscillating said nozzles, means 'for reversing said nozzls ouickly at the end of each stroke to'cause "said 'nozzles to vmove 'at substantially constant speed thrcuighc'iutv each stroke, said reversing means including a valve mechanism and stop members, and a linkage interconnecting said piston and said nozzles and including means for moving said nozzles always in opposite directions 'nozzles -for `loscillating saidnoz'zlcs rapidly aecoeae in a manner to reduce vibration in the'apparatus. 6. In an hydraulic log vbarking apparatus, Va pair of nozzles mounted for oscillation ina common plane, means for oscillating said nozzles, means for reversing said nozzles quickly at the end of each stroke to cause saidnozzles to 'move at substantially constant speed throughout each stroke, said reversing means including a' valve mechanism and stop members, and a linkage interconnecting said firstnamed means and said nozzles and including means for moving said nozzles always in opposite directions in a manner to reduce vibration in the apparatus'.

7. In an hydraulic log barkingV apparatus, a pair of nozzlesmounted for oscillation in a cornmon plane, a iluid cylinder and piston for voscillating said nozzles, means for reversing said noz'- zles'quickly at the end of each stroke to cause said nozzles to move at substantially constant speed throughout each stroke, a linkage interconnecting s/aid piston and said nozzles andincluding means for` moving vsaid nozzles always in opposite directions Vin a manner to 'reduce vibration inthe apparatus, vand means for Vsimultaneously advancing and rotating the log being barked.

8. In an hydraulic lpg barking apparatus, a pair of nozzles mounted for oscillation in a common plane, means for oscillating said nozzles, means for reversing said nozzles quickly at the end of each stroke to cause said nozzles'to ,move at substantially constant speed throughouteach stroke, said reversing means including a valve mechanism and stop members; a linkage interconnecting said iirst-named means and said nozzles and including means for moving said nozzles always inopposite directions in a manner to reduce vibration in the apparatus, and means for simultaneously advancing and rotating the log being barked.

9; Hydraulic barking apparatus comprising a iiattened nozzle for delivering a flattened jet of water, 'a pivotal mounting for said nozzle havingits pivotal axis substantially parallel to the plane of said flattened jet, means for oscillating said nozzle'on said pivotal mounting, vmeans for reversing the movement of said nozzle quickly at the end of each oscillatory stroke, pivotal oscillatory means operatively connected with said nozzle oscillating means and located oppositely to said nozzle for opposed movement to balance the vibratory forces of oscillation, and means Afor simultaneously rotating and advancing the log being barked.

Y10. Hydraulic barking apparatus comprising a nozzle for Vdelivering 'a jet of water, a pivotal mountingfor 'said nozzle, meansfor oscillating said nozzle on said pivotalmounting', means for reversing thernovement ,of saidnozzle quickly at thev end of leach oscillatory stroke, pivotal oscillatorymeans operatively connected with said nozzle oscillatingmeans vand located oppositely to said nozzle for opposed movement to balance the vibratory forces of oscillation, and means for simultaneously rotating and advancing the log being barked.

11. In a hydraulic log barking apparatus, a pair of nozzles mounted for oscillation relative to each other in a common plane, 'power-operated means including a fluid cylinder and piston for oscillating said nozzles rapidly in said common plane, and a linkage system between Vsaid power-operated means andneach of said nozgles to move said nozzles always in opposite directions toward and away from each other in a manner to reduce vibration in the apparatus.

MILES LOWELL EDWARDS.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date Swigert Aug. 14, 1934 Bezner Jan. 1, 1935 Sloan Oct. 1, 1935 Wallace Mar. 26, 1940 Number Number

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