FR2541210A1 - CAM RATCHET LIFT FOR CONVEYOR SYSTEMS - Google Patents

Abstract

THE INVENTION RELATES TO A CAM RATCHET ELEVATOR FOR A CONVEYOR SYSTEM OF THE TYPE INCLUDING SWIVEL CHAIN PUSHERS OR CAM RATCHETS 24 WHICH CAUSE THE MOVEMENT OF PART HOLDERS 22 IN THE SYSTEM. THE ELEVATOR INCLUDES A RAMP MECHANISM WHOSE RAMP IS NORMALLY PLACED SO AS TO COME IN CONTACT WITH EMPTY RATCHETS AND ELEVATE THEM ON A 104 CAM RAIL WHICH KEEP THEM OUT OF THE ROAD, BUT IS ACTUATED BY PART HOLDERS FOR THE LIFT. '' ELEVATE SO THAT THE SUPPORTS AND RATCHETS SO ENGAGED MOVE TO THE RIGHT OF THE LIFT WITHOUT ANY EFFECT.

Description

25412 1 O

  The present invention relates to a

  cam ratchet for conveyor systems.

  In overhead systems of motorized conveyors

  sees and free having, for example, pushers on chain or cam pawls, it is common that in predetermined locations of the system, for example at points of switch located at the junction of converging conveyor lines-o work supports from the two lines move through the switch on a common load track, work supports

  from a primary conveyor line or main line

  cipal move in the switch as long as there is a workpiece support on each successive push button

  the chain Workpiece supports located on the other line

  Conveyor belt, or auxiliary line, accumulates at the switch point, and the head support is released in the switch every time an empty pusher from the main line arrives at the switch In these situations, the chains The two feed lines drive continuously The auxiliary line diverges 2541 zi O 2. from the auxiliary load track to the point of switch, so that the pushers of the auxiliary chain move laterally away from the supports at the point of divergence and leaves the stationary support at the entrance to the referral zone In usual practice in a conveyor system of the type involved here, a next pusher of the auxiliary chain comes

  then in contact with the rear pawl of the push holder

  pull the latter through the switch to a point where the front drive pawl can be attacked by the empty main line pusher However,

  as the ratchet on the main line should move

  cer through the switch to come into contact with the front drive pawl of the standstill and moreover, because of the timing of the two controls

  conveyor, the main line chain pusher

  the vacuum must be high to be released in order to avoid

  the risk of it being trapped against the support of the

  auxiliary gene located in the switch area In practice, a lifter for the empty chain pusher or cam ratchet is provided along the main conveyor line just at the head of the switch to raise the empty cam ratchet on an elevated rail that extends through the location of the switch and keeps the pawl high until it has moved to a position immediately behind the front drive pawl of the support, moment when the pawl of the empty main line falls and comes into contact with the drive pawl of the stationary support so

  to move the latter in the system.

  It is heretofore common practice

  read cam ratchet risers with

  inclined ramp parts positioned so as to

  come into contact with pushers of the empty chain and working to bring them up on the cam track, for 3.

  routing to the right of the Cepen- turnout point

  In order to prevent the elevation ramp and the rail from coming into contact and interfering with the pawls in contact with the work supports, it is also common to fix the active parts of the elevation.

  with a return spring withdrawal mechanism,

  nism placed in the path of guide rollers with which the supports are normally fitted so that the

  contact of these rollers with the removal mechanism

  places the ramp of the pawl lift on one side and out of the way of the cam pawls This removal mechanism generally works satisfactorily, but is extremely noisy during operation and is subject to excessive wear mainly due to large springs of actuation with which it is normally equipped with

  so as to ensure the return of the ramp to its normal position

  male after each operation of the mechanism In this regard, it

  it is important that the removal mechanism works each

  that once a workpiece support from the main load line

  cipal crosses the switch position; and, in the function-

  normal operation of an industrial conveyor system, a

  significant, if not most, number of customers

  main line cams are generally in contact with the workpiece supports so that the number of engaged pawls far exceeds the number of empty pawls Therefore, as the elevator is brought back in

  rear by each workpiece support as it approaches

  the switch is actuated repeatedly at relatively close time intervals during the

  normal functioning of the system

  focus on the lifespan of the risers and to compensate for the fatigue of the springs which increases during the

  lifetime of the mechanism, it is necessary that the res-

  originally comes out much stronger than it should

  Being It follows that the spring resists action-

4.

  lift with relatively large force

  of, especially when new or relative-

  new, and that an important force is therefore born-

  necessary for the workpiece support to activate the lifting

  As a further consequence, the supports frequently tend to stick or catch on the elevator and, as the elevator mechanism is mounted along the

  load track, the resulting lateral force exerted

  this on the support causes excessive wear both of the support guide rollers and of the track flanges, on which the rollers move On the other hand, as the spring gradually weakens due to fatigue and other factors , it sometimes happens that

  does not return the elevator to its normal operating position

  operation so that empty pawls are not sometimes raised to be released as it should be,

  which results in the fact that there is

  be a support at the point of referral It is obvious that this problem is particularly critical, if it occurs only intermittently, which is generally

the case.

  In order to avoid the drawbacks of ratchet lifts fitted with removal mechanisms

  return spring, we previously proposed action-

  ner the ramp by a parallel linkage arrangement

  pivoting gram which is mechanically triggered

  re to maintain the ramp in a normal safe position in order to lift empty pawls on the cam rail but is actuated by the workpiece supports to release the trigger mechanism so that the

  support drive pawls are not high

  ves on the cam rail but can pass through the switching area, or by a change of conveyor having no effect, ^ An important object of the present invention 5. is a cam ratchet elevator which, is higher to the two types of prior art devices which it has

  above question The elevator of the present invention

  tion has all the advantages that can be attributed to a parallelogram elevator compared to devices fitted with return spring removal mechanisms

  and has another advantage, namely that it is mechani-

  simpler and therefore easier to install

  taller than the parallelogram elevator and is of a

  more efficient and less prone to damage

  In addition, the elevator of the present invention has the advantage of actuation

  controlled by workpiece supports in both directions

  tions; that is to say, when it is moved to a non-operating position to allow the pawls driving the workpiece supports to move in line with the elevator without effect, and also when it returns to the normal position where it is operational for passing empty cam pawls on the cam rail, which

  go translates to the fact that the moving parts of the eleva-

  are less exposed to strong shocks during the

  and they are quieter to operate.

  In addition, the elevator of the present invention exhibits

  the advantage that the supports can be supported in pas-

  health by the position of the elevator without having anything to do with the elevator itself, which is generally placed at a certain height in the air and

  sometimes in locations with difficult access.

  The present invention will be well understood when

  of the following description made in conjunction with the

attached sins in which -

  Figure 1 is a partial plan diagram

  a point of referral in a motorized conveyor system

  laughed and free representing a typical situation which

  no more cam ratchet elevator,

  6. ment illustrating the main and auxiliary conveyor lines which converge at the point of referral and a ratchet elevator according to the present invention; Figure 2 is a vertical cross-sectional view, on a larger scale, taken along line 2-2 of Figure 1, but showing a workpiece support on the load track and a drive chain with the chain pusher or cam pawl in engine contact with the support;

  Figure 3 is a partial elevational view

  side of the conveyor system shown in Figure 2;

  Figure 4 is a partial elevational view

  side view, taken in the direction of arrows 4-4 in Figure 1, and more particularly representing the ramp

  of the elevator and the rail and their association with the rail

  load; Figure 5 is an enlarged view of the lifting mechanism shown in Figure 4 and associated parts of the load track, the workpiece support and the cam pawl; and Figure 6 is a vertical cross-sectional view, taken along line 6-6 of Figure 5. Reference will first be made to Figures 1-4 which show a typical free and motorized conveyor system and a point of referral of a type with which the elevator of the present invention is intended to be used The particular system represented here comprises conveyor lines, each comprising tracks

  drive and load parallels 10 and 12, respectively

  The training track 10 is arranged directly

  above the load track 12 and at a certain

  distance from it, and has the general shape of a

  be in I, 14 On the other hand, the load track 12 comprises a pair of opposite channels, spaced laterally, 16 and 18 In practice, the drive track 10 and the load track 12 are maintained at a spacing

  uniform by a plurality of chairs 20, spaced long

  tudinally having the shape of an inverted U which are welded, or rigidly fixed in another way, to the beam 14 and the channels 16 and 18, as can be seen,

  better in figure 2 The chairs 10 are in their turn

  from a fabricated superstructure (not shown) of the plant building in which the conveyor system

  is installed Part supports 22 can move

  cer along the load track 12 by the action of spaced pushers on a chain, or cam pawls 24,

  which are shown here pivoting on a chain of

  drag 26 hanging on wheeled carts 28

  mounted so as to move on the lower wings

  res of the track 14 of drive in the form of an I-beam. The particular support of part 22 represented here by way of example is of the type similar to those described in the patents of the United States of America n C 3 415 201

  and N O 3 667 399, which we will assume here known For sim-

  fold the description and make it easier to understand,

  only the main parts of the supports and their mo-

  definition required by the present invention are

write here in detail.

  More particularly, the workpiece support 22 comprises front and rear-wheeled carriages 30 and 32

  which are connected by a bar 34 to which are suspended

  due the pieces by means of a suitable hook such as

  the one shown in 36 The carriages 30 and 32 move

  cent between the two channels 16 and 18, their wheels being

  supported by the lower wings, as shown

  felt in FIG. 2 Spaced in the longitudinal direction, pivotally mounted and comprising counterweights, vertical pawls for driving and holding 8. 38 and 40 mounted on the front carriage 30 protrude above the channels constituting the load tracks,

  and normally surround the lower end of

  dragging of a cam pawl 24, as shown in FIG. 3, so as to interconnect in a motor way

  but removable the chain 26 and the support 22 Each click

  quet 24 can tilt for a limited distance around

  its pivot axis so that it can be moved

  elevation and be disengaged from the pawl 38 of

  support drag, but its upper end pivots

  aunt can come into contact with a fastening member 42 by which it is fixed to the chain 26, so as to

  limit the pivoting movement in the downward direction -

  in front of the pawl and position the lower driving end of the pawl, hanging freely slightly above track 12, as shown in FIG. 2 The rear carriage 32 comprises a plate 44 disposed relative to the pawl of a following support so that '' a chamfered rear edge 46 of the plate comes into contact with the cam pawl of the next support and releases it from the support to allow a plurality of supports to assemble at given locations

of the system.

  The cam ratchet elevator of the present invention

  tion, broadly designated by the reference

  48, is shown here in association with an aid point

  guillage typical of a classi- air conveyor system; that in this regard, it is assumed that the conveyor system comprises a primary or main conveyor line 50, and a secondary or auxiliary conveyor line 52, which converge at a point of referral represented broadly by the reference 54 As it is best seen in Figure 1, the drive chain 56 of the main conveyor line 50 extends through the area 54 -from the point of referral and continues without interruption at

-2541210

  9. from this point following a common conveyor line 67 On the other hand, the drive chain 58 of the secondary conveyor line 52 diverges from the zone 54 of the point of referral, at the entrance of the latter as represented by the reference 60 The charging tracks 62 and 64

  conveyor lines 50 and 52, respectively, extend

  tooth-converging towards the referral area 54 where they

  can be selectively linked by a switching element

  the pivoting linkage 68 to the load track 66 of the common conveyor line 67 The switch element 68 can be either of the conventional motorized type, actuated by a jack supplied by a control valve and an appropriate detection device, such as '' a limit switch or the like, arranged for example in the path of movement of the workpiece supports when they approach the point 54 of the tracks 62 and 64, or of a conventional type which is actuated automatically

  and directly by the workpiece supports during their removal

  placement and entry into the referral area.

  The two types of switches in question

  tion above are conventional and well known in the art,

  and there is no point in describing them in detail-

  to understand the system of the present invention.

  Suffice it to say that in the particular system of con-

  voyeur shown here, the room supports 22 of the

  main conveyor gen 50 move successively-

  without interruption in the routing zone 54 and on the common conveyor line 67 as long as each chain pusher or cam pawl 24 of the drive chain 56

  is integral with the workpiece support which is thus

  trailed Under these conditions, the switching element 68 is, of course, positioned so as to connect the load track 62 of the main conveying line 50 to the

  load track 66 of the common conveyor line 67.

  In the situation described here, by way of example, the sup-

  10. workpiece ports approaching the point of referral 54 and being on the auxiliary conveyor line 52, are accumulated in a manner well known in the art,

  the head support located in the accumulation zone

  tion very close to the point of referral while the work supports of the main conveyor line 50

  move through the referral area so when

  an empty pawl 24 of the main conveyor line

  arrives, it signals to the stop which maintains the sup-

  workpiece ports accumulated on the auxiliary conveyor line

  link 52 to release the head support in such a rela-

  time with command 56 from the con- line

  main journey that the front carriage of the head support has moved into the switching area 54 and is waiting on the load track 66 of the common conveyor line 67 ready to be hooked by the empty cam pawl when the latter arrives at this point so as to fill the void in the line of workpieces moving in the conveyor system The stop mechanism which keeps the workpieces accumulated on the auxiliary conveyor line 52 and the means signaling it to have to release the head support are

  also conventional and well known in the art.

  The cam pawls 24 of the drive chain 58 of the auxiliary conveyor line 52 pass over the accumulated workpiece supports 22 without consequence, and this as described in detail in the patents cited above, since the cam plates 44 and the stop at the front of the accumulated supports prevent the pushers

  do not come into engagement with the pawls

  dragging of the accumulated supports However, when the stopper releases the head support, it makes the drive pawl of the support accessible so that it is hooked, so that the first chain pusher which is present on the drive chain 58 comes s engage in 11. the drive pawl, push the head piece support out of the accumulation area, then drive it into the switching area 54 At this point, the

  chain pusher begins to move away laterally

  workpiece support while the drive chain

  this 58 crosses the curved section 60 of the track 58.

  A gradual divergence of the anatu- chain pusher

  actually, for the final effect of removing it from the support of

  piece, leaving the latter disengaged from control 58.

  The stationary workpiece support is located at the point of

  track 54 until the following pusher of the drive chain 58 reaches the plate 44 of the support and engages

  above, when the front drive face 70, incli-

  born forward and downward, the pusher hangs under the corresponding chamfered and inclined face 72

  of the support cam plate and push the support through

  to the point of referral to a position where the

  support front carriage is on the con- line

  joint travel 57, the drive pawl thereof being arranged for engagement by the empty chain pusher on the main conveying line 50 As indicated

  previously, the timing is such that the support

  from the secondary or auxiliary conveyor line 52 is moved through the switch point to the hooking position of the common conveyor line 67 before the empty cam pawl of the drive chain of the conveyor line main 50 reaches the latching position When the stop holding the workpieces accumulated on the secondary conveyor line 52

  releases the head carriage, the pivot element 68 pivo-

  te to connect the load track 64 of the con-

  auxiliary trip 52 to the charge track 66 if the element

  the referral is motorized as described above,

  or alternatively, the medium itself activates the interrupt

  guard while moving through the referral area 12.

  if the switch is of the type actuated by support.

  The problem involved in the present invention

  tion is due to the fact that if the chain lifter is empty

  24 of the main conveyor line 50 can move

  cer in the switching zone 54 in the totally dependent position in which its lower drive end is arranged just above the load track, as shown in FIG. 2, it moves laterally towards the workpiece support which is already there, with its drive end in the same horizontal plane as the support Therefore, there is a possibility, depending on the timing of the operation and the particular construction of the workpiece support, that the empty cam ratchet gets stuck against the side of the media and causes an incident which could damage or even

  to break the pieces stuck together or even possible-

  certain auxiliary or associated parts, of the system

  such as the control of the main conveyor line

  Some of these contingencies or all of them can, of course, cause the conveyor system, and therefore the production system, to stop for a considerable period of time, so that the cause of the stop is localized.

  and proceeds to its repair The possibility of a boince-

  ment in the switching area 54 is aggravated to a certain extent in the conveyor system shown here by the fact that the drive ends of the chain pushers 24 have relatively long side portions 74 and 76 (FIG. 2) so as to move the front carriage of the head piece support entering the switching point 54 from the auxiliary conveying line 52 as far as possible in this zone 54 before the pusher disengages from the support and to ensure the operation of

  valves, limit switches and the like, action-

  pusher born in other locations 13.

of the system.

  The manifestation of the preceding contingency is prevented by the cam pawl elevator 48 of the present invention, which is mounted on the load track 62 of the main conveyor line 50 at the entrance and along the zone of switch 54, and whose function is to raise all the empty pushers 24 of the drive chain 56, but only the empty pushers, and this

  enough for the drive ends to

  ment of these lifters are raised to a height greater than any part of the workpiece support

  waiting in the referral area In practice, the

  valve 48 maintains each empty pusher 24 in the state of el

  vation until it reaches a position up to

  te at the back of the front carriage of the standby part, at which point it allows the pusher to lower

  to its fully extended position before engaging

  In this way, correct engagement of the pusher 24 with the drive pawl is ensured, without risk.

  jamming as the pusher approaches the support

Harbor.

  More particularly, the elevator 48 of the pre-

  sente invention comprises a base plate 78, or mounting plate which is welded or otherwise fixed to the outer vertical face of the channel 16 which forms one side of the load track 12; and, as shown in FIG. 1, the mounting plate 78 is fixed to the channel 16 at the head of the switching zone 54 and at a place contiguous to it. An arm 80 freely pivoting is fixed by one of its ends to the mounting plate 78 by means of a horizontal pivot 82 extending laterally outwards

which is attached to the plate.

  In the particular construction shown here by way of example (FIG. 6), the pivot 82 has the shape 14.

  a flat head screw, the rod of which extends outwards

  laughing through an opening in the floor

  than 78, and the head is countersunk in the rear face of the plate and is welded to it, as shown in 84 A sleeve 90 placed on the rod of the screw 82 is received, being mounted with play, in aligned holes practiced in the

  arm 80 and a spacer 86, and extends slightly above

  beyond the arm so that when a flat washer 92

  placed on the pivot 82 outside the arm 80 is used

  held against the outer end of the sleeve by a nut 94, the arm and the spacer can rotate freely on

  the pivot A lock washer 96 interposed between the washer-

  the 92 and the nut 94 maintains the associated parts on the

pivot 82.

  As best seen in Figure 5, the arm is disposed at the front of the pivot 82, being inclined forward and upward relative to the track 62-and is mounted so as to be animated a tilting or oscillating movement on the pivot by a part

  lateral extension 98 located at its lower end

  re rear It will be noted that the front end of the arm 80 extends substantially above the track 62 to which it is fixed and that a part in extension towards

  the front l O of a razpe element 102 and fixed to the upper edge

  The upper part of the arm rests on the rear end part of a cam rail 104, part of which is shown in the figure. Conversely, the lower part of the arm 80 extends substantially below the track 62 and in the travel path d '' a trigger pin 106 which is carried

  by the body of each workpiece support and extends laterally

  Lement from it, as shown in Figure 20 An empty pawl 24 arriving at the position of the elevator

  will cause passage on the ramp element 102 of the

  close lateral tie in extension of the pawl and its displacement

  cerient on the rail 104, which keeps the pawl in a posi-

  15. raised until this extension part falls from the front end of the rail just behind the front carriage of the part holder which has been pushed

  in the referral area as described above

  sus On the other hand, if a pawl 24 is in motor contact with a workpiece support 22, the trigger axis 106 of the support will come into contact with the rear edge 110 of the arm 80 as shown at 112 in FIG. 5, before the pawl does not engage on the ramp 102 In this regard, it will be observed that the edge 110 is inclined forward and downward at an angle of approximately 450 and that it extends sufficiently below of the trigger axis 106 so that, when the latter reaches the position indicated in 114, it has actuated by cam effect the arm 80 in an anticlockwise direction, seen in the figure, around the pivot 82, between the solid line position

  and the position in phantom shown in the figure.

  In the position of the arm 80 represented by the line mix-

  -te, the ramp element 102 is disposed at a distance im-

* bearing from above the extension parts 74 and 76 of the pawl so that the pawl and the workpiece support with which it is in contact move through and in line with the position of the elevator and the rail without

  the elevator releases the pawl from the support A second

  tie in extension 116 at the lower end of the arm projects upwards and downwards according to a

  angle of about 30 so that its bottom edge hand-

  maintains contact with the trigger axis 106 while the latter moves slowly to bring the extended part of the ramp gently and silently onto the cam rail lo 4 The rail 104 is welded or otherwise fixed to the external channel of the charging track by a plurality of fixing elements 108 in one piece, spaced apart longitudinally from one another, and is situated high enough above the charging track to stand 16.

  find above the ends of the drive pawls

  ment and maintenance of the support 38 and 40 and the

  44 Furthermore, as shown in FIG. 1, the rail 104 extends from the ramp element 102 at the front and parallel to the load track of the main conveyor line 12 to a point. located to the right of the switch area 54 but behind the final rest position of the workpiece support after it has been

pushed through this area.

  During normal operation of the con-

  voyeur, all the room supports 22 moving from

  load track 62 of the main conveyor for

  pour the switching area 54 and coming onto the load track 66 of the common conveyor line -67 pass necessary to the right of the elevator 48 During the passage of the supports 22 to the right of the elevator 48, the lateral parts extension 74 and 76 of all the pushers of the chain, or cam pawls 24, of the drive chain 56 of the

  main line overhang channels 16 and 18 of the pis-

  load as shown in Figure 2, so that the ramp 102 is in the path of movement of one or the other of these parts in extension In addition, the trigger axes 106 of the supports are arranged well at below track 62, as also shown in FIG. 2, and sufficiently on one side of the

  track to come into contact with the elevator 80 -

  In practice, the axes 106 are located longitudi-

  nally to the supports 22 so that they come into contact

  tact with arm 80 before the wing or part extending

  cam ratchet on the lifting side of track 62 comes to engage in ramp 102 Consequently,

  while ramp 102 is normally located in the tra-

  jet of movement of the wings 74 and 76, each axis of deflection

  latch will come into contact with arm 80 and will

  switch from the position shown in solid lines in figure

  17. re 5 in the position shown in phantom, also in FIG. 5, before the wing comes to engage on the ramp 102 Furthermore, after the axis 106 has raised the

  arm 80, it continues to hold it in the light position

  vation until the pawl has passed below the ramp 102 and has moved away from it, so that the support passes in front of the elevator 48 without any

  consequence A stop pin 120 carried paf 11 mounting plate

  stage 78 above the arm 80 prevents the latter from turning anti-clockwise on the pivot 82 and ensures the return by gravity of the arm to its

  normal position shown in solid lines in the figure

  gure after being actuated by a support 22.

  However, when an empty pawl 24 presents itself, there is no support 22 associated with it for raising the arm 80 Consequently, the part in extension of the

  pawl which overhangs the rail to which the lever is attached

  teur 48 strikes the ramp 102 and overlaps it, to pass on the rail 104 which maintains the pawl in the elevated position above all the parts of the support which are in the switching zone, and thus avoids any possibility of jamming of the pawl in the lateral direction against the side of the support As indicated above, the rail 104 maintains the pawl 24 in elevation until the latter reaches the far end of the rail, when it leaves the rail and falls by gravity immediately behind the support drive pawl 38 where it is positioned to come into contact with the pawl as soon as the drive chain brings them both into contact. Thus, the cam pawl 24 hooks the support 22 to the rests and moves it through the conveyor system without risk of jamming or other disaster

  that may occur in the referral area.

  Opposite the elevator 48 is a plate

  that of guide 122 which is located so as to come into 18. contact with the lateral part in extension or wing 76 of the cam pawl 24 if the latter tends to oscillate or flex horizontally on its mounting pivot in

  the direction of removal of the elevator 48.

  The approach end of the guide plate 122 is

  preferably arched outwards so as to

  finish a ramp part 124 which collects and centers any pawl 24 which is deflected to the left while it approaches the elevator and thus ensures engagement

  correct of the pawl with the ramp 102 of the elevator.

  A similar ramp 134 located at the opposite end of the

  guide plate 122 gradually releases any pressure

  lateral zion of the pawl 22 against the guide plate as it moves in line with the elevator The plate

  guide 122 can be mounted in any way

  re appropriate in accordance with the requirements of the if-

  but is shown here attached to channel 18 of the charging track by a pair of mounts

  spaced longitudinally 126 and 128.

  As mentioned earlier, a feature

  special advantage of the present invention

  tion are that the supports 22 can be retained in

  the position of the elevator if necessary or desired-

  ble for some reason, if, for example, a jamming occurs in the switching area 54 or near this area In this case, the support is

  generally maintained manually; and, while the sup-

  port moves to the left in FIG. 5, the trigger axis 106 comes into contact with the inclined lower edge 130 of the extension portion 116 of the arm and moves the arm 80 to the position shown in lines

  mixtelaissant easily pass the axis under the arm.

  The present invention is not limited to the embodiments which have just been described.

  is on the contrary susceptible to modifications and varian-

  your who will appear to the skilled person.

19.

Claims (16)

  1 Cam ratchet lift (48) for a conveyor system of the type comprising a load track (12) on which work supports (22) move and a parallel drive track (10) along which it moves a drive chain (26) or the like, the chain   drive (26) being equipped with pushers (24) solidai-   pivoting chain res, or cam pawls, which can selectively come into contact with the workpiece supports (24) and be released from them and which can operate when in contact with a support (22) to drive the latter along of the load track (12) and at least one cam rail (104)   above the charging track (12) at a predefined location   completed such as a planned system referral point (54)   for holding empty cam pawls (24) in positions   raised support disengagement positions when moving   cement pawls (24) along the location occupied by the cam rail (104), characterized in that it comprises   a ramp element (102) for raising the cli   empty cam quets (24) and pass them over the cam rail (104); support means (80) carrying the rail element (102) movable between a first active position in which the rail element (102) is disposed in the path of movement of the cam pawls (24) and in which it can come into contact with empty cam pawls (24) which can operate to move the latter on the   cam rail (104) and a second inactive position in the   which the ramp element (102) is arranged outside the path of movement of the cam pawls (24) and in which cam pawls (24) in contact with work supports (22) can pass without effect in the conveyor system elevator location; means (104) holding the support means normally in the first active position; and 20. means (110, 130) capable of cooperating with the   support means (80) arranged in the movement path   part supports (22) which can come into contact   with and be thus activated, before the engagement of customers   cam guets (24) driving the supports (22) in the valve element (102), to move the support means (80) so as to arrange the ramp element (102) in the second inactive position.   2 elevator according to claim 1, character-   laughed in that it comprises means (130) acting at the same time as the support means (80) disposed in the path of movement of the workpiece supports (22) which can come into contact with them and be actuated by them below after the cam pawls (24) driving the supports (22) are passed in line with the ramp element (102) to bring the support means (80) and the ramp element (102) back into the first active position.   3 elevator according to claim 2, character-   se in that the last cited means includes a means of   cam surface (130) on the support means.   4 elevator according to claim 1, charac-   se in that the support means comprises an arm member (80); and   means (82) for pivotally mounting the element   arm ment on the load track.   Elevator according to claim 1, characterized   in that the means now normally the means of sup-   port in the first active position comprises an element (100) projecting from the support means (80) and movable therewith, which can come into contact with the cam rail (104)   and adapted to be supported by the latter.   6 elevator according to claim 11 charac-   in that the means normally maintaining the support means in the first active position comprises: 21. an extension portion (100) of the ramp element (102) arranged so as to overhang and be   supported by the cam rail (104).   7 elevator according to claim 1, character-   laughed at in that the last mentioned means includes a surface   this cam (110) on the support means (80).   8 elevator according to claim 2, character-   se in that the last two means include   cam surfaces (110 and 130) on the support means port (80)   9 elevator according to claim 1, character-   se in that the last cited means (110, 130) can be   actuated by the supports (22) - in part during their displacement   cement in either direction on the char track   ge so as to move the support means (80).   Elevator according to claim 1, comprising   nant means (122) which cooperates with cam pawls (24) in motor contact with the supports (22) of workpiece   laterally position the cam pawls (24) to   engagement on the ramp element (102) and the ream rail (104)   11 elevator according to claim 1, compre-   nant means (122) cooperating with cam pawls (24)   in engine contact with the workpiece supports (22) for   laterally actuate the cam pawls (24) to engage the ramp element (102) and the cam rail (104), and to prevent the cam pawls (24) from moving laterally away from the elevator (80) while the pawls (24) overlap the ramp element (102) and cross it.   12 Cam ratchet lifter (48) for system   conveyor of the type comprising a load track (12) for workpiece supports (22), a cam rail (104) situated above and parallel to the load track (12), and pivoting push elements, driven, or cam pawls (24) which can come into contact with the supports (22) 22. of part to drive these on the load track (12), characterized in that it comprises: a pivoting arm (80 ), intended to be mounted at a location adjacent to the load track (12); a ramp member (102) on the arm (80) for elevating empty cam pawls (24) and passing them over the cam rail (104); means (100) for limiting the pivoting movement of the arm (80) in at least one direction in order to normally position the ramp element (102) in the path of movement of the cam pawls (24) l and   means (110) acting with the arm (80), for   before coming into contact with the supports (22) of the workpiece and thus being actuated, before the engagement of the cam pawls (24) driving the supports (22) on the cam element (102) to pivot the arm (80 ) and move the ramp element (102) away from the die path   placement of cam pawls (24).   13 Elevator according to claim 12, charac-   terrified in that the means for limiting the movement   arm pivoting part of the element   ramp (102) arranged to sit on   the cam rail (104) in the normal position of the element ramp ment (102).   14 Elevator according to claim 12, charac-   characterized in that the last mentioned means comprises a cam surface means (110) on the arm (80)   Elevator according to claim 12, comprising   taking a means (130) acting with the arm (80) to make it easier to return the ramp element (102) to its normal position after release of the arm (80) by a workpiece support (22).   16 Elevator according to claim 15, charac-   characterized in that the last-mentioned ground includes a   cam surface means (130) on the arm (80). 23.   17 elevator according to claim 15, ca-   characterized in that the two means mentioned lastly   take a surface means & -came (110, 130) on the arm (80).   18 Elevator according to claim 12, characterized in that the last cited means comprises   a cam means (110) on the arm (80) for   vant come into contact with supports (22) of part moving in one or the other direction on the load track (12) and being able to be actuated by the supports (22) to actuate in pivoting the arm (80) in order to move   the ramp element (102) out of the travel path cementing of cam pawls (24).   19 Elevator according to claim 12, charac-   terized in that it comprises a guide means (122) capable of cooperating with cam pawls (24) in motor engagement with the workpiece supports (22) for laterally positioning the   cam pawls (24) in longitudinal alignment and for   tact with the ramp element (102) and the cam rail (104).   Elevator according to claim 12, charac-   terized in that it comprises a guide means (122) of the   tined to be mounted in a place contiguous to the load track (12) opposite the swivel arm (80), this means of   guide (122) which can come into contact with at least one   of cam pawls (24) which are in contact   motor with workpiece supports (22) which can be ac-   actuated by such a contact to position the cam catches (24) laterally with respect to the load track   (12) so as to ensure engagement of the pawls with   me (24) on the ramp element (102) and the cam rail (104),   and can be operated on the other hand to prevent a   lateral placement of the cam pawls (24) away from the elevator (48) while the pawls (24) pass   on the ramp element (102) and pass through it.