US2925107A - Annular debarking mechanism and control - Google Patents

Description

Feb. 16, 1960 B. E. FITZWATER 2,925,107

ANNULAF. DEBARKING MECHANISM AND CQNTROL Filed May 6, 1958 5 Sheets-Sheet l l IN V EN TOR.

Br-uceE. Ffi'zwa her Feb. 16, 1960 B. E. FITZWATER 2,925,107

ANNULAR DEBARKING MECHANISM AND CONTROL Filed May 6, 1958 3 Sheets-Sheet I2 nvmvrox Bruce E. Fl'i'zwaker Feb. 16, 1960 B. E. FITZWATER ANNULAR DEBARKING MECHANISM AND CONTROL 3 Sheets-Sheet 3 Filed May 6, 1958 INVENTOR. Br'uceE. F1 1% wafer llllll I:

Uflied Sa e t 2,525,107 ANNULAR DEBARKING MECHANISM AND CONTROL Applica on M y 1958, serial N9 733370 firearms, ((1144-2023) a i .This invention relates to, log vdebarking apparatus, and more particularlyto ring -typewdebarking apparatus employing annular debarking. mechanism revolving about thepcriphery of a log threaded through the middle thereof, and operable to peel or skin the bark from the log as it progresses therethrough. j j j i 1 A general object of the invention is to provide debarkapparatus of the type described which includes novel mechanism expediting setting up of the apparatus so that'the annular debarking mechanism is truly centered with; respect to a log being treated. I he mechanism cor: relates the positionof theannular debarking mechanism; with the position of a clamping mechanism feeding a log,; so that the latter mechanism may be used as an indexing means for the debarking mechanism. Another object is to provide apparatus of the above description which includes mechanism operable automatically to reposition the ring debarking mechanism as a logtravelsdherethrough when necessary to take care of the taper of a log, and other irregularities in shape.

A further object is to provide hydraulic, balancing means for the ring debarker whereby the weight of the debarker is substantially entirely supported during operation: of; thejdebarking apparatus. This latter feature contributesto rapidity in response when adjustments are made in theposition of the ring debarker.

' conventionally ring-type log debarkers comprise an annular debarker frame mounting a number of radially Patented Feb. 16, 1960 feed clamp mechanisms and the debarking ring whereby movement of one is accompanied by movement of the other, and the total distance traveled by one hears a fixed ratio to the total distance traveled by the other. A cross-section of a log normallyhas a substantially circular outline. From this it follows that the distance between the two sides of a log, and the distance between a side and the middle of a log have the ratio of about 2 to 1. Thus positioning of the ring debarker so that its radial center coincides with the center of a log has-a definite relationship with respect to the adjustment necessary in the opposed clamp mechanisms to bring them tightly against the sides of a log. By interconnecting the clamp mechanisms and debarker ring, accurate, indexing of the debarker ring is possible merely by posi; tioning the infeed clamp mechanisms tightly against the oppositeoutersidesofalog :q, Thedebarking apparatus also includes hydraulic means for producing a constant but yieldable'clampingpressnre in ,the. opposed clamp mechanisms, so thatthe clamp ing mechanisms can move in and out as they follow a log contour down the length of a log. An obvious example in variation of log contour is illustrated by the taper of the normal log. For instance, a relatively. long l og may-have a diameter at one end of roughly two feet, and;

a diameter atits other end of maybe a foot.- As the log advances between the clamping mechanisms, they move together to take careof this changing diameter of the log, By coordinating movement of the ring debarker with the clamp mechanisms, the ring debarker also shifts so thatits radial center will tend to stay aligned with the log center.

A more specific object of the invention is to provide for debarking apparatus having an annular deharkena servo motor connected to and positioning the annular; debarker, andcontrols for the servo motor actuated by movement of the opposed clamp mechanisms feeding a;

inwardly projecting debarking arms or members. These debarking arms, onrotation'of the annular frame relative to a log passed therethrough, are operable to scrape or otherwise vcut away the bark and cambium layer from a log. The arms ordinarily are pivotally mounted so that the inner ends of the arms move inwardly against the surface of a log. Thedebarking apparatus also normally includes clamping means to one side of the annular debarker frame for gripping onto a log and funneling it into the center of the debarker frame.

One of the majordifficulties confronting the user of suchequipment is the proper. positioning of the annular debarker frame with respect to the clamping means feeding a log. Optimum results are obtained when the center of a log fed to the annular debarker'f rame'coincides with. the radial center of the frame. When the center of a log is olfset from this truly centered position, excessive fraying and-scraping of the ends and sides of a log occurs with consequent loss of weed material.

In prior constructions employing power-actuated means for positioning the annular debarking mechanism, positioning has been'for the most part a matter of approximation. An operator has first had to judge the diameter of a log, and then. make an educated guess as, to the proper position for the annular debarking mechanism. Such adjustments are not accurate, and further, no provision is made to take care of irregularities in the contour of a log, such as the taper normally present in a log.

This invention contemplates debarking apparatus hav new ia swsss ti s e: t v its s r s log to the ring debarker. The servo motor is initially actuated when relative movement .of the clamp mechanisms is first produced, either toward or away from each other. The servo motor on actuation moves the annular debarker in a direction related to the direction of movement in the clamp mechanisms but at a reduced rate of speed. The control for the servo motor includes a novel feedba'ck system', which functions to indicate when the debarker ring has arrived at a proper position related toa new' adjusted position of the clamping mechanisms.

The control means for the servo motor comprises a pair of piston-cylinder devices each of which have equaldisplacements on opposite sides of the piston for the device. That is, for a given amount of movement of a piston in a device, the change of the size of the chamber on one side of the piston equals exactly the change of the size of the chamber on the other side of the piston. One of the piston-cylinder devices has a total volume displacement equal to twice that of the other. Connections are I made so that movement of the debarker ring produces system is easily installed on debarking equipment, "is free of extensive mechanical linkages, and accurate in opera-" a corresponding relative movement of the piston of one of'thepiston-cylinder devices. This piston pumps fluid to the other of the piston-cylinder devices, thereby to produce relative movement between the piston and cylinder of'the other device, but at a different although related speed. A follower attached to this other piston-cylinder travels in a path adjacent to another part movable with a clamp member. The relative position between this other part and follower control the servo motor. The

tion.

These and by, theninvention, which is described hereinbelow in coni a s se w he sweet n s t isss. whsts na a other objects and advantages are attained forwardly toward the ring debarkcr.

Fig. 1 is a side elevation of debarking apparatus according to this invention showing the apparatus with a log passing down the length thereof;

1 Fig 2 is a section view along the line 2-2 in Fig. 1, illustrating the ring debarking mechanism present;

Fig. 3 is a schematic showing of an hydraulic control system suchas may be used to coordinate movement of the ring deba'rker and infeed' clamp members oi the apparatus; and

Fig. 4 illustrates a modification of the control system that may be used for positioning the ring debarker Referring now to the drawings for a description of a specific embodiment of the invention, and in particular to'Figs. I and 2, 10 indicates generally the debarking apparatus; The apparatus includes a frame 11 having longitudinal members 12, vertical members 13, and transverse members 14, properly; secured together to form asl'r'eletoriized, generally rectangular structure with a passage through the iniddle thereof to accommodate-alog passed eudwise through the apparatus. 1

"' Me'untedjon the frame at the infeed'or' rear end there- 7 of-(atihe leftof the figure in Fig. 1') is an infeed clampingman's generally indicated at 16; In front of clamping ineans'lfi is an annular debarking mechanism or ring'deba'rker 17, and mounted on the frame in front of mechanism 17 at th'e'outfe'ed end of the apparatus is an Outfeed clamping means indicated at 18. In operation, logs ar e introduced into clamping means 16 where theyare'held securely and at the same time transported Here their bark is removed, and the tail ends of the logs pulled from the debarker by clamping means 18. conventionally a conveyor, such as conveyor-19, feeds logs endwise to clamping means 16.

Infeed clamping means 16 comprises three yo-yo rolls 21-; 22 and 23. These all have substantially the same shape, each having built-up end peripheries and reduced center pe'ripheriesintermediate their ends, as indicated by thedot-ted, outlines of the infeed rolls superposed over the section view of Fig. 2., Conventiohally the peripheral surfaces of the rolls are provided with flutes or other gripping means to increase the bite of the rolls.

Lower rolls 21, 22 constitute a lower clamping mechanism of the infe ed clamping'means, and upper roll 23 iunctions as an upper clamping mechanism'spaced from and" opposed to the lower clamping mechanism. The lower rolls rotate about fixed axes, and are rotatably mounted on frame 11 by bearing members 27, 28 tatably receiving journal portions of shaft extensions provided each roll. The lower rolls are interconnected to rotate together by means of a chain 29 reeved about sprockets secured to a shaft extension of each roll. A driving chain 31 and motor 30 rotate the lower rolls in unison and in a clockwise direction viewing the rolls in Fig. 1.

Upper roll 23 of the upper clamping mechanism of the infeed clamping means is provided with shaft extensions which are rotatably mounted in bearings 36 These bearings are carried on a pair of opposed sliding blocks 37, one supporting each end of the roll (one of which is obscured in Fig. 1). These blocks each have formed along their end edges elongated grooves which slidably seat on oppositely disposed flanges 38 projecting inwardly into the space between vertical members. 13 at the infeed end of the apparatus. The flanges provide rail means guiding a block in vertical movement toward and away the lowerclamping mechanism.

,Power actuated means move upper roll 23 toward and aw-ay'the lower clamping mechanism. In the embodiment: illustrated, this. takes the fornrof an expansiblecontractible, double action piston-cylinder or jack"4l-" mounted with the cylinder portion thereof secured to a transverse member 14- of the frame and with the rod of the j'ack extending downwardly andaflixed' to a brace bar 42 interconnecting blocks 37 on either sidevof the apparatus. r

Outfeed clamping means 18 is similar to infecd clamping means 16. Outfeed clamping means 18 has an upper roll 46 which is mounted for vertical movement toward and away a lower set of rolls -47, 48. The upper roll constitutes an' upper clamping mechanism and-the lower pair of rolls function as a lower clamping" mechanism. As in the case in the infeed clamping means, the upper of the rolls 46 is mountedfor vertical movement toward and away the lower clamping mechanism by blocks- '51 carrying bearings supporting journal portions of'shaft extensions for the roll. Blocks 51 are slidable vertically in flanges or ra ls 53, 54 projecting toward each other from rear uprighvmembers-B; Double acting jack or piston-cylinder 52 powers the upper clamping mechanism up and down. V

' The ring debarkermechanism disposed intermediate the in'feed and outfeed'elam ing mea s is conventional inconstruetion. The mechanism includes a revolvable, donut shaped debarking' frame 56 havingt'an annular bearing portion 57 at the forward and rear ends thereof rotatably mounted in annular races 58. Pivotally' mounted on the debarker frame 56 intermediate for-ward andrearends of the frame and with their nonpiv'oted ends-projecting intothe central space encompassed by frame 56 are a'series of debarking arms'or members-6 1. These arms have scraper or hoe portions 62'at their inner, nonpivoted ends which are operable 'to' scrape against the peripheral surface of a log'to'rem ove its bark on rotation of frame 56 about the log. The 'sides of the debarkiug arms facing the infeed side of the apparatus slop'e away from theinfeed side and have a spiral turn, enabling theen'd of a loggto push the arms radially outwardly when the log end is initially thrust internecenter of the debarking framet', Suitablemechanism- (not shown) yieldably urges'the inner ends of arms 61' and hoe portions 62 radially inwardly against a log with a predetermihedforce. i P 9 The ring debarker mechanism, as are the upperclamp; ing mechanisms of the infeed and o'utfeed clamping means, is mounted for movement up and down in a verti cal path. The radial'center-of the annular debark-ing mechanism is movable'upand down in-a vertical'plane extending: through the longitudinal'center'of a log passing through the apparatus. The reduced center portions of the various rolls of the infeed and outfeed clamping means center a log longitudinally with the radial center of the ring debarker, and the centralporti'ons of the; upper clamping mechanisms move up and down in this same vertical plane. v I

With respect to the mounting of the ring debarke'r, races 58 supporting the ring frame of the debarker arecarried in a carriage structure indicatedfgenerally; at'71'. This structure comprises forwardand rear" mounting plates 70 (see Fig. 2) to which races 58 are-rigidly secured as by welding Plates 70 are fastened securely t'o a sjkeletonized structure formed of vertical side members 72, transverse members 73, and longitudinal and horizontal interbracing members 74.. The ends. of the plates on each side of the, apparatus are, interconnected by hood plates 75. i V a j The. carriage is slidable up and down centrally be tween two sets of'opposed vertical members 13,,and" is centered between these members against longitudinal shifting by shoes' 76secured to the carriage, andsliding on face, portions of members13; A pair of pulleys 8'1 rotatably secured to opposite ends of aninterhraceme'niber 74' located on each side of the carriage ride} up 'and' down on flange. portions of members 13" and hol'd the; carriage from shifting laterally and out' of'alignment with the path of a log transported through the apparatus.

s e together with' the debarking arm's mounted on the frame' is rotated'in races by means,

78, 79.: Belt 79,.is reeved-directly-about ring frame .56, the ring frame being provided with a cylindrical pulley surface about its outer periphery.

. Motor means are provided for moving the carriage and the ring debarker mechanism up and down. This comprises a pair of single acting piston-cylinders or jacks 86, 87'(expansible-contractible motors) disposed one on one side and one on the other side of the carriage, and each connected at one end to the carriage 71 and at its other end to frame member 12 of main frame 11.

It will be noted that a pair of piston-cylinders are employed for moving the ring debarker mechanism up and down, and that a single piston-cylinder is used for each of the forward and rear clamping rolls 23, 51. Piston- cylinders 23, 51 are of substantially the same size. .Each may be the same size as, or somewhat smaller than, piston- cylinders 86, 87. In the usual instance,-

the piston-cylinders are powered from the same high pressure fluid supply. As a consequence, clamping rolls 23, .51 move when adjusted at about twice the'speed of the ringdebarker mechanism. l 1

. Control means'or mechanism is provided for regulating movement of the various parts and interconnecting the ring debarking mechanism and the forward clamping roll 23 whereby movement of one is accompanied by movement of the other. The control mechanism and the parts employed are best shown schematically in Fig. 3. While some of the control parts are shown in Figs. 1 and 2, many of the valves, fluid lines, and control components have been excluded from these figures for reasons of clarity.

"Referring to Fig. l, secured to a sliding block 37 on one side of the apparatus isa bracket 91 to which is secured a pair of cams 92 and 93. Cams 92 and 93 are spaced vertically one from the other, and each move in a vertical path up and down with upper roll 23. The cams are offset laterally'one from the other, so that the vertical path of cam 92 lies beside but is laterally offset from the vertical path of cam 93. r

' Secured to an upright frame member 13 on the same side of the apparatus as cams 92, 93 is the cylinder portion of an elongated piston-cylinder device 96. A rod 97 for the piston-cylinder extends through the entire length of the piston-cylinder, and has secured to its lower end a plate or follower member mounting a pair of cam operated signal valves designated S1 and S2. These are laterally offset as are the cams. Signal valve S1 is aligned with cam 92 so that an actuatingfinger for the valve will engage cam 92 on relative movement of the two parts past each other, to actuate the valve. Signal valve S2 is aligned in a similar manner with cam 93.

Actuation of piston-cylinder 96 produces movement vertically either up or down of valves S1, S2, and valves S1 and S2 move in parallel paths adjacent the parallel paths of cams 92 and 93.

Secured in fixed position to the frame member 13 mounting cylinder 96 is the cylinder portion of another piston-cylinder device 101. The cylinder of piston-cylinder 101 is secured to the frame laterally outwardly from the frame so as to be out of the way of movable carriage 71. The rod of piston-cylinder 101 extends through the entire length of the piston-cylinder, and has its lower end atlixed to an interbrace member 74 of carriage 7 1. In this manner, movement of the ring debarker mechanism is accompanied by movement of the piston of piston-cylinder 101.

The upper end of piston-cylinder 101 is connected by conduit 102 to the lower end of piston-cylinder 96. The lower end of piston-cylinder 101 is connected by conduit 103 to the upper end of piston-cylinder 96. The conduits constitute means forming a closed circuit between the two piston-cylinders, and providing for fluid interchange between the two devices. When fluid is displaced from the upper portion of piston-cylinder 101 by raising its piston, the fluid displaced enters the' lower end of the. piston chamber andcauses the piston of t his. device.

to rise a proportionate amount. Lowering ofithe piston.

of device 96 takes place in a similar manner.

Since the piston rods of both piston- cylinders 96, 101 extend entirely through the cylinders of the devices, each device has equal displacements on opposite sides of the piston for the device. The pressure area of pistoncylinder 101 is twice that of piston-cylinder 102. Thus movement of the piston rod of piston-cylinder 101 is accompanied by a corresponding movement of the piston rod of piston-cylinder 96, but the total movement of one is exactly twice that of the other. The two piston-cylinders constitute an hydraulic, feedback mechanism feeding back to the follower plate mounting valves S1, S2 a movement proportioned to the movement occurring in the ring debarking mechanism. They also constitute a pro portioning means in the control system.

With reference now m Fig. 3, the hydraulic circuit controlled by cam operated signal valves S1 S2.will be. explained. In the discussion, the expression -valve spool controlled ports" refers to those ports ofla valve which are closed or opcnedby operationof -the ,spool of the valve. The expression. ffluid actuating ports? refers to those ports of an hydraulically actuated v'alve which lead drawings, the valves are shown as elongated rectangular blocks, and the conduits shown as connecting with the short sides of a block are connected to the fluid actuating ports of the valve. Those conduits connecting with either of the long sides of a block are connected to valve spool controlled ports. p j

As can be seen in Fig. 3, two' of the valve spool controlled ports of cam operated signal valves S1 and S2 are connected by conduits 111, 112, and 113, 114, respectively, to the oppositely disposed .fluid actuating ports of hydraulically actuated pilot valves P1 and P2, A valve spool controlledport of each of these pilot valves is con nected, by'conduits 116 and 117, respectively,'toone-o the fluid actuating ports of a pilot regulatedcontrol va'lve' C1. Control valve C1 in turn regulates'the admission or. exhaust of pressure fluid from the lower ends of single acting piston- cylinders 86, 87 moving the debarking mechanism. Manually operated valves M1, M2 and M3 provide manual means for regulating the operation of piston- cylinders 86, 87, piston cylinder 41, and piston-cylinder 52,-'respectively.

Valves M1, M2 and M3 are conventional three-position valves having valve spools controlling inlet and exhaust connections between four valve spool controlled ports. Each of the valves has spring means urging the spool of the valve to a neutral position located intermediate .two other positions. In Fig. 3, therefore, these valves (as well as all others having springs centering a valve spool to a neutral position) are shown with springs indicated diagrammatically within the rectangle representing the valve. Buttons are also shown to indicate that these valves may be operated manually.

In all the valves M1, M2, and M3 (as well as inall other three-position valves discussed) the dotted lines through the valve indicate the flow of fluid through the valve when the valve is in neutral position. If no line is shown for a valve spool controlled port, that port is closed when the spool is in neutral position. The valve spool for each valve when displaced upwardly in the valve in Fig. 3 produces parallelflow connectionsin the valve, i.e., fluid flows directly across the valve from a spool controlled port on one side to a spool controlled port directly opposite. Moving the valve spool in the opposite direction produces reverse connections, i.e., the lines of flow from a port on one side to a port on the other side cross each other.

Cam operated signal valves S1 and S2 are also threeposition valves, and therefore each is shown as including springs. Valves S1 and S2, instead of being manually operated, are actuated by movement of cam fingers/1 21,

gees-abs 122 indicated as connected to the spools of the valves. The camfingers are pivoted in a conventional manner to thecasings for-the valves, and each has a bifurcated inner end (not indicated) which surrounds the valve casing and, by, means of a sliding connection, produces sliding movement of a valve spool on pivotal movement of the cam finger connected thereto. In Fig. 3, when the outer, cam end of a cam finger for a signal valve is pivoted downwardly, the valve spool of the valve is displaced upwardly and a parallel flow through and between opposite spool controlled ports results. Movement in the opposite direction reverses the connections, so that a crossed flow through the valve is produced.

Pilot valves P 1 a'nd P2 are conventional two-position valves, and are a ctuated only hydraulically. Since they are two-position" valves, no springs are indicated. Pressurefluid admitted. to an actuating chamber of a valve (as in) the ease cram otherhydraulically actuated valves hereindis'cusse'd) pushes the valve spool of the valve away from'the fluid actuating port which admitted the pressure flit-id. Since valves P1, P2, are two-position valves, the

valve spoolremains in one position until actuated in the opposite direction. In Fig. 3, when a spool of a pilot valve moves downwardly a crossed flow throughthe spool controlled ports results, whereas pushing a spool upwardl-y produces a parallel-flow. The pilot valves have four spool controlled ports, however it will be noted that meet the ports, of each. valve is indicated as plugged. (Plugs are indicated at 168, 169.)

Control valve C1 is similar to manually operated valves M1,,M2 and M3, in that it also is a threeposition valve and spring biased to a neutral position wherein fluid flow through the valve takes place as shown by the dotted lines indicated for the valve. The valve diflers from valves M1, M2, and M3,, however, in that it is hydraulicallyactua-tedandnot manually actuated.

A high pressure pii'mp 125 driven by motor 124 pumps fluid under pressurenirough high pressure conduits 126, 127 and-128 to a spoolcontrolled port of valves S1 and S2, r spectiv ly. In their neutral position, the spools for these valves close off the ports connected to conduits 127, 128; and conduits 111, 112, 113, and114 connect to sump, indicated' at S, through conduits 137, 138.

Pump 125 also delivers fluid under pressure through conduit 131, a conventional variable restriction valve 132, and a divider valve 138, to a spool controlled port of valve M1, ,from whence fluid flows through conduit, 133 to valve C1, through conduit 134 to valve M2, and through" conduit 136 to valve M3. The valve spools of valves C1, M2, and M3 in their neutral position connect conduits 133, 134, 136. Divider valve 138 in line 131 is conventional, and divides the pressure fluid flowing in conduit '131 to direct part of the, fluid through. conduit 139' directly to valve M2.

Conduits 141, 142 connect spool controlled ports of valves C1 and M1, respectively, to a conduit 143 leading to the lower ends of the piston- cylinders 86, 87 moving the ringdebarker. Conduits 146 and 147 connect spool controlled ports of valve M2 with opposite ends of pistoncylinder 41 connected to upper forward clamping roll 23. Included in conduit line 147 is a conventional pressure reducing valve, 151 responsive to the pressure in the line between the valve and piston-cylinder 41 and regulating the maximum pressure of pressure fluid passing through the valve. Conduits 152, 153 connect spoolcontrolled ports of valve M3 with opposite ends of pistoncylinder 52 moving the upper rear clamping mechanism up anddown. Included in conduit line 153 is pressure reducing valve 156 similar to valve151. Bypassing pressure reducing valves 151 and 156 are conduit segments. cOImecting with conventional relief valves 157, 158, respectively. Valves 159, 160 are conventional check valves, each accommodating unidirectional flow of fluid downwardly through the. valve only. F' A low pressure pump 161 driven by motor 124 pumps t ll fluid urinepressure through low p essure eohduit illtif 163, and 164 to a valve spool controlled port of valve P1 and valve P2. It will be remembered that pilotvalves P1 and P2 have valve spool controlled ports closed by plugs 168, 169, and that each also has a valve spool controlled port connected with a fluid actuating port of control valve, C1. Another valve spool controlled port of valve P1 and valveP2 is connected, by conduits 171, 172, respectively, to sump. v

Low pressure pump 161 is also connected by conduit 176 through a pressure reducing valve 177 similar to valves 153;, 156, to conduit 178, through the valve spool controlled ports of an hydraulically actuated on-ofl valve 179, to conduit-180 connecting with conduit 143.- The.

spool of valve 179 connectsthe valve spool controlled 7 ports of the valve when low pressures are in conduitI'SQ and closes, oif the ports with high pressures in"conduit valve, 181. I

Conduit 163 connects low pressurepump 161 through a conduit191, a pressure reducing valve 192 (resembling valves 151, 156) and the valve spool controlled ports of an hydraulically actuated on-oif valve 193 (similar to valve 179) with conduit 146 leading to the bottom end of piston-cylinder 41. Conduit1 91 is also connected through reducing valve 192 and a relief valve 201 to sump. Pressure reducing valve 192 is further connected by conduit 202 and through the spool controlled ports of an hydraulically actuated on-off. valve 203 (similar to. valves 193, 179), conduit 294 to conduit 152 connected to the bottom end of piston-cylinder 52 moving the upper rear clamping mechanism up and down. Conduit 163'leading from the low pressure pumpalso connects by conduit 206 and through the valve spool controlled ports of an electrically operated on-ofl valve. 297 through conduit 208 to conduit 153 and the upper" side of piston-cylinder 52. Asimilar connection is pre. vided between conduit 163 to piston-cylinder 41 through conduit .191, the valve spool controlled. ports of anelectrically operated on-ofif valve 211, and conduit 1 47.

The electrically operated on- vofl valves 207, 211 are conventional, each having valve spool controlled ports connected to each other when the solenoid for the valve is energized, and out of communication with each otherwhen the solenoid for the valve is deenergized. Switches 216, 217 operate the valves, these switches closing a circuit between 'pairs of supply conductors. j

Relief valves 218, 219 connect conduits 126, 162, respectively, to sump. These are includedv as a safetyprecaution.

In general terms, high pressure pump and the conduit system connecting this pump to the piston-cylinders moving the ring debarker mechanism and the front and rear upper clamping rolls constitute a high pressure conduit system supplying pressure fluid to the various pistoncylindcrs. Pump 161 and the conduits associated'therewith supply pressure fluidat relatvely low pressure for actuating pilot valves P1 and P2 controlling the admission of pressure fluid to the actuating chambers of valve C1. Further, the low pressure pump, through reducing valve 177, conduit 178, and valve 179 provides a low pressure conduit system for introducing a constant supply of rela tively low pressure fluid to the lower ends of piston cylinders 86, 87, for the purpose of partially balancing the weight of the ring debarker.

Pump 161, conduit 191, electrically operated valves 207 and211, and reducing valves 151, 156 are part of a conduit system included for the purpose of admitting low pressure fluid. constantly to the upper side of the piston-cylinders moving the front and rear upperclamping rolls, whereby they may be continuously and yieldably urged downwardly with a constant bias. This part of the circuit therefore comprises a compensator control; mechanism automatically adjusting the. position ot-the 130. Conduit 17s is connected to sump through relief:

from and rear up er clamping mechanisms whereby these clamping mechanisms follow the contour of a log while exerting a predetermined pressure downwardly thereon. f The operation of the hereinabove set forth control system will now be described. For purposes of explanation, it will be assumed that the upper clamping mechanism of the forward clamping means is spaced from the lower clamping mechanism a predetermined distance, and that the ring debarker mechanism is aligned with its radial center midway vertically between the upper and lower clamping mechanisms of the forward clamping means. In this condition, cams 92 and 93 are directly above and below cam fingers 121, 122, respectively, of the cam operated signal valves. Cam 92 is in the path of cam finger 121 and cam 93 is in the path of cam finger 122. The two cams each constitute a first trigger means movable in a path conjointly with the forward upper clamping mechanism, and cam fingers 121, 122 each comprise second trigger means engageable with a first trigger means and movablein a path adjacent the path of a first trigger means but at a speed determined by the speed of the ring-type debarker.

:It a log is inserted between the clamping mechanisms of the front clampingmeans which has a diameter less than the spacing between the clamping mechanisms, an operator adjusts manual control valve M2 so that the spool of the valve moves downwardly in Fig. 3 producing crossed connections between opposite spool controlled ports of the valve. As a-result, pressure fluid from pump 125 is delivered through conduit 126, 131 and valves M1 and C1 (which are in their neutral positionslto conduit 134, through valve M2 to conduit147, Where it passes through pressure reducing valve 151 to the'top side of piston-cylinder 41. Exhaust from the bottom side of the piston-cylinder takes place through conduit 146, valve M2, conduit 136, valve M3, .to sump. The upperclamping mechanism moves downwardly and with it cam 92 (cam 93 movingaway from cam finger 122). Downward movementof cam 92 pivots cam finger 121 downwardly, with its inner end moving upwardly and the valve spool of signal valve S1 moving Upwardly.

Upward movement of the spool of valve S1 produces parallel connections between opposite spool controlled ports of the valve, and conduit 127 connected to pump 12S delivers pressure fluid to conduit 112 and the lower actuating chamber of valve P1. The upper actuating chamber of valve P1 exhausts through valve S1, and conduit 138 to sump. The spool of valve P1 moves up under the momentary admissionof pressure fluid thereto. Cam 92 on passing cam finger 121 moves over the cam finger with the finger returning to its original position and the spool of valve S1 returning to a neutral position. Movement of the valve spool of valve P1 upwardly produces parallel connections through the valve, with pump 161 and conduit 164 being connected to conduit 116 and the; upper actuating chamber of valve C1.

The actuating chamber on theopposite side of valve C1 is connected throughconduit 117 to pilot valve P2 which is initially set so that its valve spool occupies a down position in the valve with crossed connections existing between the oppositely disposed spool. controlled ports of the valve. As a consequence, the lower actuating chamber of valve C1 may exhaust through conduit 117, pilot valve P2, and conduit 172 when the spool of C1 moves down. Movement of the spool of valve C1 downwardly produces crossed connections between opposite spool controlled ports of the valve.

As a result, the bottom ends of piston- cylinders 86, 87 exhaust through conduit 143, 141, and valve C1 to conduit 134 and sump. The pistons of the single acting piston- cylinders 86, 87 lower themselves drawing in fluid from sump to their opposite sides. The ringdebarker mechanism moves downwardly together with these pistons. a p

As the annular debarker moves downwardly, fluid is wai t pumped from piston-cylinder 101 to piston-cylinder. 96, with the follower and the cam operated signal valves moving downwardly at twice the speed of the annular debarker.

When the operator has adjusted the upper clamping mechanism of the front clamping means to its proper position and released manual valve M2, the upper clamping mechanism becomes stationary. The ring debarker continues its movement downwardly until cam finger 121 overtakes cam 92 and moves across it. This movement produces upwardly movement of the cam finger relative to signal valve S1, and downward movement of the spool in the valve. As a consequence, pump 125 pumps fluid through signal valve S1 to conduit 1'11 and the upper fluid actuating chamber of pilot valve P1. The lower fluid actuating chamber of the valve exhausts through valve S1 to conduit 138 and sump. Downward movement of the spool of pilot valve P1 takes place. Theupper fluid actuating chamber of valve C1 exhausts through conduit 116 and pilot valve P1, and the spool of valve C1 returns to a neutral position. In this position, exhaust for con duits 143, 141 is shut off, and the ring debarker stops.

Since the follower mounting valves S1, S2 moves at twice the speed of the ring debarker, total movement of the debarker before it is stopped always equals half that of the forward upper clamping mechanism. Piston- cylinders 96, 101 thus constitute step down means in the device. Operation of the mechanism is similar when the upper clamping mechanism of the forward clamping means is moved upwardly instead of downwardly. In this instance, when the clamping mechanism is moved upwardly, cam 92 moves away from cam finger 121 and cam 93.moves across cam finger 122 to pivot it upwardly with downward movement of the valve spool in signal valve S2. This produces a crossed connection between the oppositely disposed spool controlled ports of valve S2, and pressure fluid is admitted to conduit 114 and the bottom of valve P2, exhaust from the top of valve P2 occurring through conduit 113. Pilot valve P2 (which previously had its valve spool disposed downwardly therein) is moved up wardly, and pressure fluid from conduit 164 passes through the parallelly connected spool controlled ports of valve P2 to conduit 1-17 and the lower actuating chamber of valve C1. The upper actuating chamber of valve C1 exhausts through valve P1 (its valve spool resting in a down position).

Pressurizing of the lower actuating chamber of valve C1 moves the valve spool upwardly in Fig. 3, and pressure fluid flows from pump through the valve to conduits 141, 143 and the lower ends of piston- cylinders 86, 87. This raises the ring debarker.

When the adjusted position of the forward upper clamping mechanism is reached, the follower mounting the cam operated single valve S1 and S2 overtakes the cams, movement of cam finger 122 over cam 93 occurs, the cam finger pivots downwardly, and the valve spool of signal valve S2 moves upwardly. Pressure fluid is admitted to conduit 113, and the spool of valve P2 moves downwardly. Valve C1 assumes a neutral position and movement of the ring debarker ceases.

To obtain automatic following of the forward or rear upper clamping rolls of the device, electrically operated valves 211 and 207 are used. Considering the front upper clamping mechanism, if switch 216 is closed. and the solenoid of valve 211 energized, the valve is opened with the introduction of pressure fluid from pump 1-61..through conduit 191 to conduit 147, reducing valve .1'51and the upper end of the piston-cylinder 41. As a result, a constant pressure is exerted downwardly on the upper front clamping mechanism determined by the'setting of the pressure reducing valve. If the diameter of a log momentarily increases as it passes through the front clamping means, by reason of a knot or other irregularity, the upperfront clamping roll rriechanism moves upwardly whey 11 the upward pressure on the mechanism exceeds the downward pressure produced in piston-cylinder 41 by the introduction of pressure fluid to its upper end. Reducing valve 192 admits a relatively small amount of pressure fluid through valve 193 and conduit 146 to the lower side of piston-cylinder 41. This prevents a vacuum condition from being set up in the lower part of the piston-cylinder on upward movement of the clamping mechanism. On the'other hand, if the log diameter decreases, the piston of piston-cylinder 41 moves downwardly under the urging of pressure fluid delivered to the top of the piston-cylinder through pressure reducing valve 151. Exhaust from the lower part of piston-cylinder 41 takes place through valve 193 and reliefvalve 201 (which is set to open at a pressure only slightly above the pressure of fluid flowing through reducing valve 192).

. Hydraulically operated on-off valve 193 is included to enable raising of the front hold-down roll. When pump 125 is connected to conduits 134, 147, the high pressure resulting in line 147 operates to close valve 193. Pressure fluid is delivered directly to piston-cylinder 41 to raise its piston without bleeding of the pressure fluid through valve 193 and relief valve 201 to sump.

The hydraulic compensator circuit for the rear upper clamping mechanism (roll 46) is substantially the same as the circuit just described. Valve 207 corresponds to valve 211, and when actuated by closing of switch 217,

permits the introduction of fluid from pump 161 through reducing valve 156 to the upper end ofpiston-cylinder 52. Downward movement of its piston is enabled by the discharge of fluid from the bottom end of the piston-cylinder through conduits 152, 2114, 'valve 203, conduit 202 and relief valve 2121. When valve M3 is actuated to raise roll 46, valve 203 is closed by the pressure existing in line 204, to prevent bleeding of pressure fluid through conduit 202 and valve 201.

When switch 216 is closed and valve 211 opened, it will be apparent that by incorporation of the feedback and follower system disclosed, movement of, the upper front clamping mechanism either up or down as a log progresses through the apparatus is accompanied by automatic compensating movement in the ring debarker. This is a highly desirable feature.

Concerning the hydraulic balancing means included in the control system which partially balances the mass of the-ring debarker mechanism, conduit 162 connects pump 161 through a reducing valve 177 to conduits 178, 143 and the lower ends of piston- cylinders 86, 87. Thus a regulated, relatively low pressure is delivered at all times to the bottom ends of these piston-cylinders tending to raise their piston portions against the weight of the ring debarker. Pressure reducing valve 177 is adjusted so that the-pressure is not sufiicient to actually produce rising movement of the ring debarker. Hydraulically actuated on-off valve 179 performs the same function in this part of thecircuit as on-oft valves 193 and 203. If the annular debarker is to be raised, the relatively high pressure of fluid introduced into conduit 143 functions to close valve 179 to prevent bleeding of pressure fluid through valve 181.

Fig. 4 illustrates an electric circuit such as may be used in controlling the admission of pressure fluid to pistoncylinders 86, 87. In this figure, a solenoid operated valve C2 is included to perform the function of hydraulically operated valve C1 shown in Fig. 3. Solenoid operated valve C2 is a three-position valve (spring biased to a neutral position) having opposed spool controlled ports 221, 222, and 223, 224. Ports 222, 224 are connected to conduits 134, 133 of the system disclosed in Fig. 3, port 221 to conduit 1-40, and port 223 to conduit 141. The electrical components shown in Fig. 4 generally replace cam operated signal valves S1, S2, the pilot valves P1 and P2,. and the various conduits interconnecting these ports;

l2 switches SW1 and SW2. These correspond to'cam opera ated valves 51 and S2. Cam operated fingers 2.31 and 232 control switches SW1 and SW2. As in the case of the first embodiment, cam 92 moves up and down in the path of one finger (finger 231), and cam 93 moves up and down in the path of another finger (finger 232).

Switches SW1 and SW2 are conventional, each having four switch points, indicated at 240 through 244, and 246 through 249. Associated with pairs of switch points in each switch is a switch contact, exemplified by contact 250. These are each spring biased, in the case of the upper pair of switch points of a given switch to a closed position, and in the case of the lower pair of switch points of a given switch to an open position. The cam finger of Referring to Fig. 4, moun-ted on the follower and movtable with the annular debarking mechanism are a pair of each of the switches is pivoted to the switch body, and has a forked end or rocker portion 251 abutting the switch contacts of the switch. The ends of each rocker portion are free of the switch contacts they abut. Thus, in action, if the rocker portion of a switch is pivoted in a clockwise direction in Fig. 4, the connections between the upper pair of points in the switch is opened, and the lower'pair of switch points remain disconnected. If the rocker portion is pivoted in the other direction, the upper pair of switch points remain connected, whereas a connection is produced between the lower pair of switch points.

Switch SW1 controls a solenoid 261 ganged to the valve spool of control valve C2, and when energized is operable to move it downwardly. Switch SW2 controls solenoid 262 ganged to the valve spool of valve C2 and is operable when energized to move it upwardly. Solenoid 263 is the holding solenoid for the circuit controlling solenoid 261, this solenoid being ganged to a pair of switches 266, 2 67. Solenoid 271 is the holding solenoid for the circuit controlling solenoid 262, this solenoid being ganged to switches 272 and 273. 5 V

In operation, when the forward upper clamping mechanism of the forward clamping means is moved downwardly to move cam 92 down across finger 231, a closed contact exists momentarily between switch contacts 243, 244 and solenoids 263, 261 are energized. This closes switches 266, 267, switch 267 acting as a holding switch keeping solenoid 263 energized, and switch 266 maintaining solenoid 261 energized. As a result, the valve spool of valve C2 moves downwardly, a crossed connection is produced between the fluid controlled ports of the valve, and pressure fluid flows from conduit 133 to conduit and sump. The cross connection also connects conduit 141'to conduit 134, and exhaust from the bottom ends of piston- cylinders 86, 87 takes place, with the ring debarker moving downwardly.

. As in the case of the first embodiment, when the moveinent of the forward clamping roll is stopped, cam finger 231 overtakes cam 92 and is pivoted in the opposite direction. This serves momentarily to open the connection be tween points 241, 242. Solenoid 263 is deenergized and as a consequence, solenoid 261 becomes deenergized with the valve spool of valve C2 returning to a neutral position.

Movement of the upper clamping mechanism of the forward clamping means upwardly, in a similar manner, causes ene'rgizing'of solenoids 271 and 262. The valve spool of C2 is moved upwardly, parallel connections are produced, and pressure fluid flows from conduit 133. to conduit 141. When movement of the clamping mechanism stops, and the cam finger 232 overtakes cam 93, the. cam finger is pivoted in the opposite direction tode energize solenoids 271, 262, and to cause the spool of controlvalve C2 to return to a neutral position.

It is claimed and desired to secure by Letters Patent:

1. In ring-type debarking apparatus having a pair of opposed clamping mechanisms adapted to engage opposite sides of a log passed endwise in a path therebetween, annular debarking mechanism rotatable about a log advanced between said clamping mechanism, and mounting means mountingoneof saidclampingmechanisms and said debarking mechanism accommodating movement of the two mechanisms in directions which occupy a commonplaneextendinglongitudinally of a log advanced between said clamping mechanisms, the improvement comprising a first motor means connected to and moving said one clamping mechanism, a second motor means connected to the debarking mechanism for moving the' debarking mechanism, and control means regulating said second motor means responsive to the position of said one clamping mechanism, said control means having a pilotmeans, means operatively connecting the pilot means to said one'clarnping mechanism whereby it is regulated by the position of said one clamping mechanism and means operatively connecting said pilot means to said second motor means whereby the pilot means regulates" the second motor means and thus controls the position of said debarking mechanism.

Q2, Self-adjusting ring-type debarking apparatus comprising a frame,a pair of opposed clamping mechanisms and means mounting the clamping mechanisms on said frame, one over the other, the means mounting the upper of said clamping mechanisms accommodating movement thereof vertically toward and away from the lower of said clamping mechanisms, annular debarking mechanism rotatable about ,a ,log advanced endwise between said clamping mechanisms and mounting means mounting the debarking mechanism on said frame rearwardly of said clamping mechanisms, ,said last-mentioned mounting meansaccommodating movement ofthe debarkingmechanism ina vertical direction, manually controlled fluid motor means connected to said upper clamping mechani-sm foradjusting its position to enable moving of the same-against a log disposed between the clamping mechanisms, compensator means automatically adjusting the position of saidiupper clamping mechanism to compensate for variations, in the diameter of a log and holding said upper clamping mechanism against. a log with a predetermihedpressurqa second motor means connected to said, debarking mechanism for moving the debarking mechanism, and control means regulating said second motor means responsive to the position oi said upper clamping mechanism.

3 The apparatus of claim 2 wherein said control means comprises pilot means operatively connected to said second motor means to activate the same, and means for actuating said pilot means, said means for actuating said pilot means being operatively connected to the upper clamping mechanism and the debarking mechanism so as to be responsive to the position of both of the two mecha- 'nisms and including proportioning means whereby the pilot means is actuated, to initiate activation of said second motor means by movement of said upper clamping mechanism toward an adjusted position, and actuated to deactivate said second motor means by movement of said upper clamping mechanism into an adjusted position and movement of said debarking mechanism a distance equal to a predetermined fraction of the total movement -occurring'in said upper clamping mechanism.

4. In ring-type debarking apparatus having a pair of .opposed clamping mechanisms adapted to engage opposite sides of a log passed endwise in a path therebe- -t'ween','a'nnula'r debarking mechanism rotatable about a 'log' advanced between said clamping mechanisms, and mounting means mounting one of said clamping mechanisms and said debarking mechanism accommodating movement'of the two mechanisms in directions which -occtipYakommonplane extending longitudinally of a log fadvan'ced between saidclamping' mechanisms, the improvement comprising a first motor means connected to andrpr moving" said one clamping mechanism, a second motor means connected to and for moving said debarking :m'echanism, "and control means regulating said second motor means responsive to the position of said one clampingmechanism,said control means having a first trigger means movable in a path and means operatively connect- -ing said-first trigger means and saidone clamping mecha- :14 nism whereby the triggerrneans moves conjointly with said one'clamping mechanism, a second trigger means engageable with "said firsttrigger means and] movable in a path adjacent the path of said first trigger means and means operatively connecting said second trigger means and said debarking mechanism whereby the second trigger mechanism moves conjointly with said debarking mechanism, the means connecting said second trigger means and debarking mechanism having proportioning means whereby the second trigger means moves at a speed that is a predetermined multiple of the speed of said debarking mechanism, the pilot means connected to said second motor means actuated to initiate activation of said second motor means by engagement of said first and second trigger means on initial movement of said one clamping mechanism toward an adjusted position, said] pilot means being actuated by a subsequent engagement of said trigger means to deactivate said second motor means.

5. The debarking apparatus of claim Mix/herein the means connecting the second trigger means and debarking mechanism comprises a follower mounting said second trigger means, and hydraulic mechanism operatively connected between saiddebarking mechanism and follower, said hydraulic mechanism having a pair of expansible piston-cylinder devices, eachhaving equal displacements on opposite sides of the piston for the device, and conduit t means interconnecting said piston-cylinder devices forming a closed hydraulic circuit thereinbetween, one of said piston-cylinders being connected to said debarking mechanism, the other of said piston-cylinders being connected tosaid follower. i

6. In ring-type debarking apparatus having a pair of opposed clamping mechanisms adapted to engage opposite sidesof a log passed endwise in a path thereinbetween, one clamping mechanism being movable toward and away from the other, and annular debarking mechanism mounted rearwardly of said clamping mechanismsrotatabie about a log advanced between said clamping mechanisms, said debarking mechanism being movable in a direction substantially parallel to the direction of movement of said one clamping mechanism, the improvement comprising servo motor means connected to said debarking apparatus for moving the same, and control means regulating said servo motor means responsive to the position of said one clamping mechanism, said control means having pilot means for activating and deactivating said servo motor means, a first trigger means movable in a path conjointly with movement of said one clamping mechanism, a follower and means connecting said follower to said debarking mechanism for movement conjointly with said debarking mechanism but at a speed which is a predetermined multiple of the speed of said debarking mechanism, and a second trigger means mounted on said follower engageable with said first trigger means and movable in a path adjacent said first trigger means, said first and second trigger means engaging each other and actuating said pilot means to activate said servo motor means on initial movement of said one clamping mechanism to an adjustedposition, said first and second trigger means engaging each other and actuating said pilot means to deactivate said servo motor means upon movement of said clamping mechanism into an adjusted .position.

7. In a ring-type debarking apparatus having a frame, a pair of opposed clamping mechanisms mounted on said frame adapted to engage opposite sides of a log passed endwise in a path thereinbetween, and annular debarking mechanism mounted on said frame rearwardly of said clamping mechanisms rotatable about a log advanced between said clamping mechanisms, one of said clamping mechanisms and said debarking mechanism being movable mechanisms and mounted for movement in directions which occupy a common plane extending longitudinally through the center of a log advanced between said clamping mechan sms. the. improvementycompri sing motor means for moving s id debarking mechanism, and control means for said motor means, said control means comprising a follower, a pair of expansible piston-cylinder devices having piston and rod ends, each having equal displacements .on opposite sides of the piston for the device, one of said piston-cylinder devices having a total displacement volume equal to a fraction of the total displacement volume of. the other, closed conduit means connecting the cylinders of said devices for fluid inter change, means securing one of said ends of one of said devices to said frame and the other of said ends of said one device to one of said movable mechanisms, means securing one of said'ends of the other vof said devices to said frame and the other ofsaid ends of said other device to said follower, and triggering means interposed between said follower and the other of said movable mechanisms connected to said motor, means foractivating and deactivating s'aid motor means. I

l sgln' aring-typefdebarking apparatus having a pair of opposed clamping inechanisms adapted to engage opposite sides of'a log passed endwise in a path thereinbetween, and annular debarking r'nechanism,mounted earwardly of said clamp'ingmechanhrnsrotatable about a log advanced bet'weensaid clampingmechanisms, one of said clamping mechanisms and said deba'rking mechanism being movable mechanisms and mounted for movement in directions which occupy a common plane extending' longitudinally through the center of a log advanced between said clamping mcchanisms, the improvement comprising a first motor means for moving 'said one clamping mechanism, a servo motor means for moving said debarking' mechanism, "and control means for said servo motor means, said control means comprising a first trigger means movable in a path conjointly with one of said movable mechanisms, a follower and a second trigger means mounted on said follower; feedback means moving said follower conjointly with the other of said mechanisms in a path adjacent the path of sad first triggermeans, said first and second trigger" means being engageable with each other, said feedback means moving said follower at a speed different from but related to the speed of movement of said other mechanism, and pilot means actuated by engagement of said first and second trigger means for activating said second motor means.

9. In a ring-type debarking apparatus having a pair of opposed clamping mechanisms adapted to engage opposite sides of a log passed endwise in a path thereinbetwcen, and annular deb-arking mechanism mounted rcarwardly of said clamping mechan sms rotatable about a log advanced between said clamping mechanisms, one of's aid clamping mechanisms and said debarking mechanism being movable mechanisms and mounted for movement in directions which-occupy a common plane extending longitudinally through the center of a log advanced between said clamping mechanisms, the improvement comprising 'a first fluid, motor means operable to move, when activated, said one clamping mechanism at a predetermined rate of speed, a second fluid motor means operable to move, when actuated, said debarkng mechani'sm'at a predetermined rate of speed which is not more than half the rate of speed of movement of said one clamping mechanism, and control means for said second fluid motor means, saidcontrol means comprising a firsttrigger means movable in a path conjointly with said one. clampingmechanism, a follower and a second trigger means mounted on said follower, feedback means moving said follower .conjointly with said debarking mechanism in a path adjacent the path of said first trigger means, said first and second trigger means being engageable with each other, said feedback means moving sa d follower at a rate of speed which is greater than but not more than twice the speed of movement of said sl n mechanism; afldpilot means actuated. by

t l c '16 e sem t 0f s ifir'st n eco idit l sse means for, activating'said second fluid motor means. 10. In a ringype deb'arking apparatus having a frame, a pair of pposed clamping mechanism mountedfion said frame adapted to engage opposite sides of a log passed endwise thereinbetween, and annular debarking mechanism mounted on said frame rearwardly of said clamping mechanisms rotatable about a log advanced be tween said clamping mechanisms, one of said clamping mechanisms, and said deb'a'rking' mechanism being mounted for movement in directions occupying a com-1 mon plane extending longitudinally through the center of a log advanced between said clamping mechanisms, the improvement comprising a first fluid motor ime'an's o'per able to move, when actuated, said one clamping mecha nism at a predetermined rate of speed anda manually operated control therefor, a second fluid motormcans operable I01 move, when actuated' Said debarking mecha nism at a predetermined rate of speed which is 'not more tha half the rate of'sp'eed of said first fluid motor means, and control means regulating said second fluid motor means, said control means comprising a movable follower, a pair of 'expansiblepiston-cylinder devices hav ing piston and rod ends, each having equal displace ments on opposite sides of the piston for the device, one' of said devices having a total displacement volume equal to approximately twice that of the other, closed conduit means connectingth'e cylinders of said devices for fluid interchange, means connecting one of said ends'of said one device to said frame and the other of said ends; of the device to said debarking mechanism, means connecting" one of said ends'of the other device to said frame and' the other of said ends'of the device to said follower, a pair of cooperating trigger means, one mounted on said follower and one mounted on said one clamping mechanism, respectively, said triggermeans moving in parallel paths past positions whil'ethey engage with one another, and pilot means actuated by mutual engagement of said trigger means to activate said second fluid motor means. 11. In ring-type debarking apparatus having infeed clamping means for advancing a log along a path through the apparatus and an annular debarking mechanisfn'on the outfeed side of said clamping means rotatable about a'log advanced in said path, the combination of expansible-contractible fluid motor means connected to, said debarking mechanism for raising and lowering the same, high pressure conduit means supplying pressure fluid at relatively'high pressure tosaid fluid motor means and to the side thereof' wherein the fluid motor means is actuated to' raise the debarking mechanism and control means therefor regulating the flow of pressure fluid responding to variations in the diameter of a log passing through the apparatus, and a second conduit means introducing pressure fluid constantly at relatively low pressure to the same side of said fluid motor means.

12. In ring-type debarking apparatus having infeed clamping means for advancing a log along a path through the apparatus and an annular debarkingmechanisrn on the outfeed side of said clamp ng means rotatable about a log advanced in said path, the combination of expansible-contractible fluid motor means connected to said debarking mechanism movable in one direction to lift and in the other drection to lower the same, a first conduit means introducing aconstant supply of. pressure fluid to one side of said fluid motor means and urging the latter in a lifting direction withla forcenot exceeding that required to raise the debarkingmechanism, a second conduit means introducing pressure fluid to said one sideof said fluid motor means under a pressure sufliclent to raise the debarking -mechanism,,and control means responding to variations. in the d ameter of a log passing thr ugh the ap aratus regulating the flow of pressure fluid through said second conduitrneans.

113; It; ringetypedebarking apparatus thecombination' of a frame, a pair of opposed clamping mechanisms and means mounting the clamping mechanisms on said frame, one over the other, the means mounting the upper of said clamping mechanisms accommodating movement thereof vertically toward and away from the lower of said clamping mechanisms, annular debarking mechanism rotatable about a log advanced endwise between said clamping mechanisms and mounting means mounting the debarking mechanism on said frame rearwardly of said clamping mechanisms, said last-mentioned mounting means accommodating movement of the debarking mechanism in a vertical direction, expansible-contractible fluid motor means connected to said debarking mechanism for raising and lowering the same, high pressure conduit means supplying pressure fluid at relatively high pressure to said flu d motor means and to the side thereof wherein the fluid motor means is actuated to raise the debarking mechanism and control means therefor regulating the flow of pressure fluid through the conduit means, low pressure conduit means introducing pressure fluid constantly at relatively low pressure to the same side of said fluid motor means, and power-actuated means for moving said upper clamping mechanism to adjusted positions, the control means for said high pressure conduit means being actuated by movement of said upper clamping mechanism responding to the spacing of said pair of opposed clamping mechanisms.

14. In ring-type debarking apparatus the combination of a frame, a pair of opposed clamping mechanisms and means mounting the clamping mechanisms on said frame, one over the other, the means mounting the upper of said clamping mechanisms accommodat ng movement thereof vertically toward and away from the lower of said clamping mechanisms, annular debarking mechanism rotatable about a log advanced endwise between said clamping mechanisms and mounting means mounting the debarking mechanism on said frame rearwardly of said clamping mechanisms, exnansible-contractible fluid motor means connected to said debarking mechanism for raising and lowering the same, a first conduit means introducing a constant supply of pressure fluid to one side of said fluid motor means and urging the latter in a lifting direction with a force not exceeding that required to raise the debarking mechanism, a second conduit means introducing pressure fluid to the same side of said fluid motor means under a pressure suificient to raise the debarking mechanism, control means for said second conduit means regulating the flow orf fluid through, and power-actuated means for moving said upper clamping mechanism to adjusted positions, the control means for said second conduit means being actuated by movement of said upper clamping mechanism.

15. The combination of claim 14 wherein said poweractuated means for moving said upper clamping mechanism comprises a second expansible-contractible fluid motor means connected thereto and movable in one direction to lift and in the other direction to lower the clamping mechanism, said last-mentioned fluid motor means having high pressure, manually controlled conduit means for the supply of pressure fluid to both sides of the motor at relatively high pressure, and low pressure conduit means introducing a constant supply of pressure fluid at relatively low pressure to the side of said fluid motor means wherein said clamping mechanism is urged in a lowering direction.

16. In a ring-type debarking apparatus having a pair of opposed clamping mechanisms adapted to engage opposite sides of the log passed endwise in a path thereinbetween, and annular debarking mechanism mounted rearwardly of said clamping mechanisms rotatable about a log advanced between said clamping mechanisms, one of said clamping mechanisms and said debarking mechanism being movable mechanisms and mounted for movement in directions which occupy a common plane extending longitudinally through the center of a log advanced between said clamping mechanisms, the improvement comprising a first motor means for moving said one clamping mechanism, a second motor means for moving said debarking mechanism, and control means interconnecting the actuation of the first and second motor means whereby one is a servo motor means and is actuated in response to actuation of the other, said control means including proportioning mechanism whereby the total movement produced in said one clamping mechanism by actuation of said first motor means is :a predetermined multiple of the total movement occurring in said debarking mechanism on actuation of said second motor means.

17. In a ring-type debarking apparatus having a pair of opposed clamping mechanisms adapted to engage opposite sides of a log passed endwise in a path thereinbetween, annular debarking mechanism rotatable about a log advanced between said clamping mechanisms, and mounting means mounting at least one of said clamping mechanisms and said debarking mechanism accommodating movement of the two mechanisms in directions which occupy a common plane extending longitudinally of a log advanced between said clamping mechanisms, said one clamping mechanism and said debarking mechanism constituting adjustable mechanisms, the improvement comprising a first motor means connected to and for moving said one clamping mechanism, a second motor means connected to and moving said debarking mechanism, and control means regulating one of the motor means responsive to actuation of the other of the motor means, said control means having a first trigger means movable in a path and means operatively connecting said first trigger means and said one clamping mechanism whereby the trigger means moves conjointly with said one clamping mechanism, a second trigger means engageable with said first trigger means and movable in a path adjacent the path of said first trigger means and means operatively connecting said second trigger means and said debarking mechanism whereby the second trigger means moves conjointly with said debarking mechanism, the means connecting one of said trigger means to its respective adjustable mechanism including proportioning means whereby the movement occurring in said one trigger means on movement of the last-mentioned adjustable mechanism is a multiple of the movement occurring in the adjustable mechanism, and pilot means operatively connected to one of said motor means for controlling the same, said first and second trigger means regulating said pilot means.

References Cited in the file of this patent UNITED STATES PATENTS 2,591,751 Whitlock Apr. 8, 1952 2,765,012 Riddell et a1. Oct. 2, 1956 FOREIGN PATENTS 39,704 Sweden Dec. 1, 1915

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