US3735854A

US3735854A - Fluid pressure motor with extensible and retractable part

Info

Publication number: US3735854A
Application number: US00153214A
Authority: US
Inventors: R Playmouth Meeting Hirsch; J F Philadelphia Tomezsko
Original assignee: PARAMOUNT PRECISION PRODUCTS I
Current assignee: PARAMOUNT PRECISION PRODUCTS I
Priority date: 1971-06-15
Filing date: 1971-06-15
Publication date: 1973-05-29
Anticipated expiration: 1990-05-29

Abstract

A fluid pressure motor is mounted at the head of a vertically extending shaft for being oscillated or turned forth and back thereby about the axis of the shaft. The motor is provided with a part extensible and retractable laterally of the shaft. The axis of the shaft is coincident with the line of intersection of a plane extending longitudinally of the fluid pressure motor and a plane extending transversely thereof. The weight of the fluid pressure motor on one side of either of said planes substantially balances the weight of the fluid pressure motor on the other side of the plane.

Description

United States Patent [191 Hirsch et al.

[ FLUID PRESSURE MOTOR WITH EXTENSIBLE AND RETRACTABLE PART [75] Inventors: Richard Hirsch, Plymouth Meeting; Joseph F. Tomezsko, Philadelphia, both of Pa.

[73] Assignee: Paramount Precision Products, Inc.,

Philadelphia, Pa.

[22] Filed: June 15, 1971 [21] Appl.No.: 153,214

UNITED STATES PATENTS Faure 198/24 May 29,1973

3,229,829 l/l966 Weatherbee ..2l4/82 Primary Examiner-Gerald M. Forlenza Assistant Examiner-George F. Abraham Attorney-'Louis V. Schiavo [57] ABSTRACT A fluid pressure motor is mounted at the head of a vertically extending shaft for being oscillated or turned forth and back thereby about the axis of the shaft. The motor is provided with a part extensible and retractable laterally of the shaft. The axis of the shaft is coincident with the line of intersection of a plane extending longitudinally of the fluid pressure motor and a plane extending transversely thereof. The weight of the fluid pressure motor on one side of either of said planes substantially balances the weight of the fluid pressure motor on the other side of the plane.

4 Claims, 7 Drawing Figures PATENIEBHAYZS I973 SHEET 1 BF 3 8 mm in INVENTOR5 RICHARD. HIRECH BY JOSEPH F. TOM ZSKO ATTORNEY.

PATENIE W29 I973 SHEET 3 OF INVENTORS RICHARD 01.414 }/0/$L4/UZ7 ATTORNEY.

HIRSCH BY JgSEPH F. TOMEZSKO FLUID PRESSURE MOTORWITI-I EXTENSIBLE AND RETRACTABLE PART BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to glassware forming machines, and particularly to a fluid pressure motor with an extensible and retracted part operable for transferring newly formed glassware from a stationary platform or deadplate onto a continuously movingconveyor.

2. Description of the Prior Art A glassware forming machine, such as the wellknown Hartford I. S. machine, may comprise a plurality of sections each including a stationary deadplate at a first station for receiving newly formed glassware, a continuously moving conveyor and means for transferring the glassware from the deadplate onto the conveyor for being advanced thereby to a second station. The deadplate and conveyor of one section of the machine may be assembled to the right hand, while the deadplate and conveyor of another section of the machine may be assembled to the left hand. Otherwise the sections may be alike. The conventional transfer means with which such right and left hand sections are furnished are not interchangeable because they themselves are constructed to the right and left hand. In addition, the conventional transfer means is in the form of a' fluid pressure motor mounted upon the head and wholly to one side of a vertically extending shaft which oscillates the motor about the axis of the shaft. The eccentric load on the shaft causes undue wear on certain parts of the motor and on the mechanism for oscillating the same. Furthermore, the fluid pressure motor is provided with an extensible and retractable part, but lacks any means for selectively adjusting the length of the stroke. Still further, the extensible and retractable part of the fluid pressure motor includes only one piston, as a consequence of which means, such as guide rods, have been employed to secure the piston against turning about its own axis.

SUMMARY OF THE INVENTION The principal object of the present invention is to removably mount a fluid pressure motor having an extensible and retractable part at the head of a vertically extending shaft in such a way that the fluid pressure motor may be used with a section of a glassware forming machine whether the dead plate and conveyor thereof are assembled to the right hand or the left hand.

Another object is to mount the fluid pressure motor centrally so that the weight thereof is substantially balanced on the shaft, and so that eccentric loading of the shaft is kept to a minimum.

Another object is to provide such a fluid pressure motor with built-in means operable for adjusting the stroke of the extensible and retractable part.

Still another object is to provide such a fluid pressure motor wherein the extensible and retractable part comprises a pair of parallel, laterally spaced pistons interconnected to secure them against turning about their axes.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of a fluid pressure motor constructed in accordance with the invention showing the extensible and retractable part partially extended, parts being broken away and others being shown in section;

FIGS. 2 through 4 are reduced sections respectively on lines II-II, III-III and IVIV in FIG. 1;

FIG. 5 is an exploded perspective view of the fluid pressure motor, part being broken away and others omitted altogether for the sake of clarity; and

FIGS. 6 and 7 are diagrammatic views showing the fluid pressure motor associated with sections of a glassware forming machine, the sections being assembled to the right and left hands, respectively.

DESCRIPTION OF THE PREFERRED EMBODIMENT The following description is directed to the specific embodiment of the invention disclosed in the drawings. It is not addressed to the scope of the invention since the invention may be practiced in a variety of forms.

Referring particularly to FIGS. 1 through 5, a fluid pressure motor constructed in accordance with the present invention, generally designated 10, comprises a main body part or block 12,

plates

14 and 16 extending respectively across the fore and aft ends of the block 12, a pair of extensible and retractable members, generally designated 17 and 18, extending through the front plate 14 and into the block 12, and an adjustable stroke mechanism, generally designated 20, extending through the back plate 16 and into the block 12.

The block 12 is rectangular in transverse section, and in both vertical and horizontal longitudinal section, as shown. Extending longitudinally through the block 12 are a pair of parallel, laterally spaced cylindrical bores or cylinders 22. At the fore end of the block 12, between the cylinders 22, are a pair of communicating

bores

24 and 26, these bores opening respectively on the bottom and the fore end of the block. At the aft end of the block 12, between the cylinders 22, are a series of communicating

bores

28, 30, 32 and 33, the

bores

28 and 33 opening respectively on the bottom and the aft end of the block.

Axially aligned respectively with the cylinders 22 in the block 12 and extending from front to back through front plate 14 are a pair of bores 34 terminating in counterbores 36. Pressed into each bore 34 is a bushing 38 provided with a radially outwardly extending flange 40 nested in the associated counter-bore 36. It will be noted that the thickness of the flange 40 is less than the depth of the counterbore 36, as shown. The inner face of the front plate 14 is provided with a groove 42 extending horizontally between and interconnecting the counterbores 36. Threaded into the top of the front plate are a pair of fittings 43, respectively directly over the bushings 38. The inner surface of each bushing 38 may be lubricated through the associated fitting 43 and an oil passage (not shown) placing the fitting in communication therewith. The front plate 14 is secured to the fore end of the block 12 by means of eight studs 44 which extend freely through holes 46 in the plate and thread into holes 48 in the fore end of the block 12. When the front plate 14 is secured in place, the groove 42 communicates with the bore 26.

Axially aligned with one of the cylinders 22 in the.

block 12 and extending from back to front through the back plate 16 is a bore 50 terminating in a counterbore 52. The inner face of the back plate 116 is provided with a groove 54 extending radially outwardly from the counterbore 52 and across the longitudinally extending vertically disposed median plane of the block 12.

Threaded into the top of the back plate 16 is a needle valve 55 communicating with the groove 54 through a suitable passage (not shown). The back plate 16 is secured to the aft end of the block 12 by means of eight studs 56 which extend freely through holes 58 in the plate and thread into holes (not shown) in the aft end of the block 12. When the back plate is secured in place, the groove 54 communicates with the bore 33.

The extensible and retractable member 17 comprises a solid piston rod 62 slidably passing through one of the bushings 38 and extending into the associated cylinder 22 in the block 12. The inner end portion of the rod 62 mounts a piston 64 fitted with a pair of axially spaced piston rings 66. The extensible and retractable member 18 comprises a piston rod 68 slidably passing through the other bushing 38 and extending into the associated cylinder 22 in the block 12. The inner end portion of the rod 68 mounts a piston 70 fitted with a pair of axially spaced piston rings 72. The fore end portion of the rod 68, designated 74, is solid, while the remainder of the rod 68, designated 76, is hollow. Threaded into the inner end portion of the hollow section 76 is a lock collar 78 provided with a central opening 80.

The

piston rods

62 and 68 mount a pusher plate 82 extending horizontally across the fore ends thereof and secured to each rod by 'a pair of studs 84 extending freely through the pusher plate and threaded into holes 86 in the fore ends of the rods. The pusher plate in turn mounts a pair of laterally spaced pusher arms 88 extending horizontally forwardly from the pusher plate. It will be understood that the pusher plate and pusher arm assembly may take various forms, depending upon the mode of operation and the work to be accomplished, e.g., preferably, the pusher arms are adjustably secured in position along the pusher plate and vertically relative to the pusher plate to accommodate glassware of different size.

The adjustable stroke mechanism 20 comprises a guide bar 90 pressed into the hollow section 76 of the piston rod 68 and extending from the solid fore end portion 74 of the piston rod 68 to the lock collar 78. The bar 90 is provided with a groove 92 extending the full length thereof and accommodating a correspondingly shaped slide 94. Extending freely through the opening 80 in the lock collar 78 and threaded through the slide 94 is the fore end of a rod 96, which carries a cotter pin 97. The aft end portion of the rod 96 is provided with a head 98 nested in the bore 50. Under the head 98 is a lock member 100 affixed to the rod 96 and nested in the counterbore 52. The lock member is provided with axially spaced circumferentially extending grooves 102 and 104 and a dimple 106. The groove 102 accommodates an O-ring 108. The lower end portion ofa pin 110 which is pressed into an opening 111 projects into the groove 104. The dimple 106 accommodates a spherical detent 112 at the inner end of a hole 114. Threaded into the outer end of the hole 114 is a set screw 116, and interposed between the detent and the set screw is a compression spring 118.

The fluid pressure motor is seated upon a base or swival plate 120 provided with parallel, laterally spaced

bores

122 and 123 communicating respectively with the

bores

24 and 28 in the block 12.

The base plate 120 in turn is seated upon a plate 124 which is provided with parallel, laterally spaced

bores

126 and 127 communicating respectively with

bores

122 and 123 in the plate 120. The plate 124 is in the form of aIICOllflI affixed to an upper end portion of a vertically extending shaft 128. The upper end portion of the shaft is detachably projected into an opening 130 in the base plate 120. A pair of studs 132 extend downwardly freely through openings 134 in the block 12 and openings 136 in the plate 120 and are threaded into openings 138 in the plate 124.

It will be observed that the bore 126 in the plate 124, bore 122 in the plate 120, bores 24 and 26 in the block 12 and the groove 42 in the front plate 14 conjointly provide an air passage 140 communicating with the fore ends of the cylinders 22, and that the bore 127 in the plate 124, bore 123 in the plate 120, bores 28, 30, 32 and 33 in the block 12, and the groove 54 in the back plate 16 conjointly provide an air passage 142 communicating with the aft ends of the cylinders 22. It will also be observed that the fluid pressure motor 10 is centrally mounted upon the shaft 128, i.e., the axis of the shaft 128 is disposed in a longitudinally extending vertically disposed plane midway between the extensible and retractable members 17 and 18.

Fluid motor 10 is operated pneumatically. Suitable conduits (not shown) from a source of pressurized air are connected to the underside of the plate 124 for supply of air respectively to cylinders 22 through the

passages

140 and 142. Referring particularly to FIG. 1, the

piston rods

62 and 68 are shown partially extended. Air under pressure is introduced through the passage 142 to the aft ends of the cylinders 22. If desired, the pressure may be reduced by bleeding air through the needle valve 55. At the same time the fore ends of the cylinders 22 are vented to atmosphere through the passage 140. As a consequence, the pusher plate 82 and

piston rods

62 and 68 are extended. The limit of traverse is reached when the lock collar 78 engages the stop 94. After a predetermined period of time, air under pressure is introduced through the passage 140 into the fore ends of the cylinders 22, and at the same time, the aft ends of the cylinders 22 are vented to atmosphere through the passage 142. As a consequence, the pusher plate 82 and

piston rods

62 and 68 are retracted. The limit of traverse is reached when the pusher plate 82 engages the front plate 14 or the heads of the studs 44.

The length of the stroke may be adjusted to suit the work to be done. A tool is applied to the head 98 of the rod 96 and the rod is turned to position the stop 94 in a selected position longitudinally of the rod 96. The cotter pin 97 guards against threading the stop 94 off the rod 96. Lock member is secured against axial movement by the lower end portion of the pin engaged in the groove 104. The O-ring 108 prevents escape of air past the lock member 100. When the head 98 of the rod 96 is turned, the rod 96 and the lock member 100 are also turned and the spherical detent 102 is forced out of the dimple 106 against the influence of the compression spring 118. As the rod is turned, the slide moves axially of the rod 96 to the selected position which affords the stroke desired.

The fluid pressure motor 10 of this invention is intended for replacing the corresponding fluid pressure motor of US. Pat. No. 3,249,200, issued May 3, 1966, to G. E. Rowe. Reference may be had to said patent for the basic glassware forming machine, and particularly for the arrangement for oscillating the fluid pressure motor about a vertically extending axis and for the mode of operation of said arrangement.

Referring particularly to FIGS. 6 and 7, which show the fluid pressure motor 10 in the environment for which it is intended, newly formed glass bottles 144 are deposited upon a deadplate 146. The function of the motor 10 is to push or sweep these bottles from the deadplate onto the conveyor belt 148. As shown in full lines, the motor 10 faces the deadplate and the pusher plate and piston rods are in retracted positions. The latter are then extended to the broken line position thereof, over the deadplate, so that the pusher arms 88 are disposed respectively behind the bottles 144. Thereupon, the shaft 128 makes a quarter turn, swinging the motor 10 to the dotted line position thereof, over the conveyor belt 148. The bottles 144 are thereby swept in an arcuate path before the pusher arms 88 to the dotted line positions thereof over the conveyor belt 148. Thereupon, the pusher plate and piston rods are retracted to prevent interference with the movement of bottles on the conveyor belt. The shaft 128 is now turned back to its initial position, whereupon the motor 10, piston rods and pusher plate assume the full line positions thereof, thus completing a full cycle of operation.

If the motor 10 is in use with a section of the glassware forming machine assembled to one hand and it is desired to transfer it to a section of the glassware forming machine assembled to the opposite hand, after detaching it from the plate 124 and shaft 128 of the first section and before mounting it upon the plate 124 and shaft 128 of the second section, it is only necessary to reverse the pusher plate 82. Thus it will be noted that the fluid pressure motor 10 is suited for use in a section of the glassware forming machine whether the section, i.e., the deadplate and conveyor, is assembled to the right hand, as in FIG. 6, or to the left hand, as in FIG. 7. Furthermore, it will be noted that the fluid pressure motor is centrally mounted, i.e., the weights of the parts thereof on opposite sides or fore and aft, with respect to the shaft 128, are substantially equal.

Referring particularly to FIGS. 6 and 7, when it is desired to detach the motor 10 from the plate 124 and shaft 128, it is necessary to reach over the hot glassware carried by the conveyor belt 146. Accordingly, it is convenient to have the motor 10 and swival plate 120 attached to the plate 124 by means of studs 132, which extend downwardly through the block 12, with heads fully exposed for easy application of a tool thereto.

While in accordance with the provisions of the patent statutes, 1 have illustrated and described the best form of the embodiment of my invention now known to me, it will be apparent to those skilled in the art that changes may be made in the form of the apparatus described without departing from the spirit and scope of the invention as set forth in the appended claims, and that in some cases certain features of my invention may be used to advantage without a corresponding use of other features.

What is claimed is:

1. ln apparatus for transferring glassware from a deadplate onto a continuously moving conveyor, the combination comprising A. a vertically extending shaft,

B. means for oscillating said shaft about its axis through a substantial angle between a first and a second position,

C. a fluid pressure motor carried by said shaft includl. a pair of laterally spaced, parallel members extensible and retractable laterally relative to the axis of said shaft, the axis of said shaft being disposed substantially midway between said mem- 5 bers,

D. means on said shaft providing a seat for said fluid pressure motor and detachably affixing it to said shaft for movement therewith including 1. a collar plate extending cross-axially of and affixed to the upper end portion of said shaft,

2. a base plate seated upon said collar plate and in turn providing a seat for said fluid pressure motor, a portion of said shaft extending upwardly from said collar plate being detachably projected into an opening in said base plate, and

3. means projected downwardly freely through the main body of said fluid pressure motor and through said base plate and threaded into said collar plate,

E. work engaging means carried by said pair of members for being extended and retracted threrewith, and

F. means for oscillating said fluid pressure motor about the axis of said shaft and for extending and retracting said pair of members and said work engaging means in predetermined timed relation in repeating cycles for transferring work from said deadplate to said conveyor.

2. In apparatus for transferring glassware from a 30 deadplate onto a continuously moving conveyor, the

combination comprising A. a vertically extending shaft, B. means for oscillating said shaft about its axis through a substantial angle between a first and a second position, C. a fluid pressure motor carried by said shaft includmg l. a block having a pair of laterally spaced, parallel cylinders,

2. front and back plates respectively extending across the fore and aft ends of said block,

3. a pair of pistons respectively workable in said cylinders, and

4. a pair of piston rods extending forwardly respectively from said pistons and through said front plate, said pistons and piston rods being extensible and retractable laterally relative to the axis of said shaft,

D. means on said shaft providing a seat for said fluid pressure motor,

E. means projected downwardly through said block and detachably securing said fluid pressure motor in position on said seating means,

F. interconnecting passage sections respectively in said motor seating means and fluid pressure motor for placing a source of pressurized air in communication with the fore ends of said cylinders for retracting said pistons including an air passage section in the form of an open groove extending across the inner face of said front plate and having opposite end portions in communication respectively with the fore ends of said cylinders,

G. interconnecting passage sections respectively in said motor seating means and fluid pressure motor for placing said source of pressurized air in communication with the aft ends of said cylinders for extending said pistons including an air passage section in the form of an open groove extending across the inner face of said back plate and having opposite end portions in communication respectively with the aft ends of said cylinders, H. work engaging means carried by said pair of piston rods for being extended and retracted therewith, and 1. means for oscillating said fluid pressure motor about the axis of said shaft and for extending and retracting said pair of pistons and said work engaging means in predetermined timed relation in repeating cycles for transferring work from said deadplate to said conveyor. 3. The combination according to claim 2 wherein the fore end of each cylinder communicates with the associated end of the air passage section provided by the groove extending across the inner face of the front plate through an annular space extending about the piston rod and provided by a recess in the inner face of the front plate.

4. In apparatus for transferring glassware from a deadplate onto a continuously moving conveyor, the combination comprising A. a vertically extending shaft, B. means for oscillating said shaft about its axis through a substantial angle between a first and a second position, C. a fluid pressure motor carried by said shaft includmg l. a block having a pair of laterally spaced parallel cylinders and detachably affixed to the head of said shaft for oscillating therewith,

3. a pair of pistons respectively workable in said cylinders, and

4. a pair of piston rods extending forwardly respectively from said pistons and through said front plate, said pistons and piston rods being extensible and retractable laterally relative to the axis of said shaft, and one of said piston rods being provided with a hollow inner end section,

D. means operable for selectively adjusting the outward stroke or traverse of the piston and piston rod assembly working in said cylinders including,

1. a stop disposed in the hollow of said piston rod section,

2. a rod extending through the back plate forwardly into the hollow of said piston rod section, the fore end of said rod being threaded through said stop, and the aft end of said rod being fully exposed at the outer face of said back plate for application of a tool thereto, and 3. means for securing the rod against axial movement including a. a cylindrical lock member provided with a pair of axially spaced circumferentially extending grooves,

b. an O-ring accommodated by one of said grooves for pneumatically sealing the opening in which said lock member is nested, and

0. one end portion of a pin carried by the back plate and accommodated by the other of said grooves,

E. lock means at the inner extremity of said hollow piston rod section arranged for engaging said stop to thereby limit the outward stroke or traverse of said piston and piston rod assemblies,

F. work engaging means carried by said pair of piston rods for being extended and retracted therewith, and

G. means for oscillating said fluid pressure motor about the axis of said shaft and for extending and retracting said pair of pistons and said work engaging means in predetermined timed relation in repeating cycles for transferring work from said deadplate to said conveyor.

Claims

1. In apparatus for transferring glassware from a deadplate onto a continuously moving conveyor, the combination comprising A. a vertically extending shaft, B. means for oscillating said shaft about its axis through a substantial angle between a first and a second position, C. a fluid pressure motor carried by said shaft including 1. a pair of laterally spaced, parallel members extensible and retractable laterally relative to the axis of said shaft, the axis of said shaft being disposed substantially midway between said members, D. means on said shaft providing a seat for said fluid pressure motor and detachably affixing it to said shaft for movement therewith including 1. a collar plate extending cross-axially of and affixed to the upper end portion of said shaft, 2. a base plate seated upon said collar plate and in turn providing a seat for said fluid pressure motor, a portion of said shaft extending upwardly from said collar plate being detachably projected into an opening in said base plate, and 3. means projected downwardly freely through the main body of said fluid pressure motor and through said base plate and threaded into said collar plate, E. work engaging means carried by said pair of members for being extended and retracted threrewith, and F. means for oscillating said fluid pressure motor about the axis of said shaft and for extending and retracting said pair of members and said work engaging means in predetermined timed relation in repeating cycles for transferring work from said deadplate to said conveyor.

2. In apparatus for transferring glassware from a deadplate onto a continuously moving conveyor, the combination comprising A. a vertically extending shaft, B. means for oscillating said shaft about its axis through a substantial angle between a first and a second position, C. a fluid pressure motor carried by said shaft including

2. a rod extending through the back plate forwardly into the hollow of said piston rod section, the fore end of said rod being threaded through said stop, and the aft end of said rod being fully exposed at the outer face of said back plate for application of a tool thereto, and

3. means for securing the rod against axial movement including a. a cylindrical lock member provided with a pair of axially spaced circumferentially extending grooves, b. an O-ring accommodated by one of said grooves for pneumatically sealing the opening in which said lock member is nested, and c. one end portion of a pin carried by The back plate and accommodated by the other of said grooves, E. lock means at the inner extremity of said hollow piston rod section arranged for engaging said stop to thereby limit the outward stroke or traverse of said piston and piston rod assemblies, F. work engaging means carried by said pair of piston rods for being extended and retracted therewith, and G. means for oscillating said fluid pressure motor about the axis of said shaft and for extending and retracting said pair of pistons and said work engaging means in predetermined timed relation in repeating cycles for transferring work from said deadplate to said conveyor.

3. a pair of pistons respectively workable in said cylinders, and

3. The combination according to claim 2 wherein the fore end of each cylinder communicates with the associated end of the air passage section provided by the groove extending across the inner face of the front plate through an annular space extending about the piston rod and provided by a recess in the inner face of the front plate.

3. a pair of pistons respectively workable in said cylinders, and

3. means projected downwardly freely through the main body of said fluid pressure motor and through said base plate and threaded into said collar plate, E. work engaging means carried by said pair of members for being extended and retracted threrewith, and F. means for oscillating said fluid pressure motor about the axis of said shaft and for extending and retracting said pair of members and said work engaging means in predetermined timed relation in repeating cycles for transferring work from said deadplate to said conveyor.

4. In apparatus for transferring glassware from a deadplate onto a continuously moving conveyor, the combination comprising A. a vertically extending shaft, B. means for oscillating said shaft about its axis through a substantial angle between a first and a second position, C. a fluid pressure motor carried by said shaft including

4. a pair of piston rods extending forwardly respectively from said pistons and through said front plate, said pistons and piston rods being extensible and retractable laterally relative to the axis of said shaft, and one of said piston rods being provided with a hollow inner end section, D. means operable for selectively adjusting the outward stroke or traverse of the piston and piston rod assembly working in said cylinders including,

4. a pair of piston rods extending forwardly respectively from said pistons and through said front plate, said pistons and piston rods being extensible and retractable laterally relative to the axis of said shaft, D. means on said shaft providing a seat for said fluid pressure motor, E. means projected downwardly through said block and detachably securing said fluid pressure motor in position on said seating means, F. interconnecting passage sections respectively in said motor seating means and fluid pressure motor for placing a source of pressurized air in communication with the fore ends of said cylinders for retracting said pistons including an air passage section in the form of an open groove extending across the inner face of said front plate and having opposite end portions in communication respectively with the fore ends of said cylinders, G. interconnecting passage sections respectively in said motor seating means and fluid pressure motor for placing said source of pressurized air in communication with the aft ends of said cylinders for extending said pistons including an air passage section in the form of an open groove extending across the inner face of said back plate and having opposite end portions in communication respectively with the aft ends of said cylinders, H. work engaging means carried by said pair of piston rods for being extended and retracted therewith, and I. means for oscillating said fluid pressure motor about the axis of said shaft and for extending and retracting said pair of pistons and said work engaging means in predetermined timed relation in repeating cycles for transferring work from said deadplate to said conveyor.