CA2167752C - Piston advance mechanism for automatic taper - Google Patents

Piston advance mechanism for automatic taper

Info

Publication number
CA2167752C
CA2167752C CA002167752A CA2167752A CA2167752C CA 2167752 C CA2167752 C CA 2167752C CA 002167752 A CA002167752 A CA 002167752A CA 2167752 A CA2167752 A CA 2167752A CA 2167752 C CA2167752 C CA 2167752C
Authority
CA
Canada
Prior art keywords
rods
cylinder
assembly
piston
piston assembly
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
CA002167752A
Other languages
French (fr)
Other versions
CA2167752A1 (en
Inventor
Donald Mark Mcmillan
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
KAISER INTERNATIONAL DEVELOPMENTS Ltd
Original Assignee
Donald Mark Mcmillan
Kaiser International Developments Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Donald Mark Mcmillan, Kaiser International Developments Ltd. filed Critical Donald Mark Mcmillan
Priority to CA002167752A priority Critical patent/CA2167752C/en
Publication of CA2167752A1 publication Critical patent/CA2167752A1/en
Application granted granted Critical
Publication of CA2167752C publication Critical patent/CA2167752C/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Classifications

    • EFIXED CONSTRUCTIONS
    • E04BUILDING
    • E04FFINISHING WORK ON BUILDINGS, e.g. STAIRS, FLOORS
    • E04F21/00Implements for finishing work on buildings
    • E04F21/165Implements for finishing work on buildings for finishing joints, e.g. implements for raking or filling joints, jointers
    • EFIXED CONSTRUCTIONS
    • E04BUILDING
    • E04FFINISHING WORK ON BUILDINGS, e.g. STAIRS, FLOORS
    • E04F21/00Implements for finishing work on buildings
    • EFIXED CONSTRUCTIONS
    • E04BUILDING
    • E04FFINISHING WORK ON BUILDINGS, e.g. STAIRS, FLOORS
    • E04F21/00Implements for finishing work on buildings
    • E04F21/165Implements for finishing work on buildings for finishing joints, e.g. implements for raking or filling joints, jointers
    • E04F21/1657Implements for finishing work on buildings for finishing joints, e.g. implements for raking or filling joints, jointers for applying tape to joints, e.g. drywall taper tools

Abstract

The mechanism consists of a crankshaft and connecting rods driving two rods which extend through the full length of the cylinder of the taper. The rods reciprocate 180°
out of phase with each other and pass through a piston assembly. Clutch mechanisms in the piston assembly engage when the rods are moving toward the head assembly and do not engage for the opposite motion. As a result the piston assembly advances toward the head assembly an increment of motion each time one of the rods moves in that direction. A mechanism in the piston assembly engages the head end of the cylinder as the piston assembly approaches the head end and prevents the clutches from engaging so that the piston assembly does not jam against the head end of the cylinder. Also, mechanism is provided to disengage both clutches and keep them disengaged so that the piston assembly is free to move as the cylinder is being filled. This mechanism involves rotating the rods to drive cams which engage the clutches to hold them disengaged. An alternate driving mechanism between the crankshaft and the oscillating rods enables adjustment of the amount of motion of the rods for turn of the crankshaft.

Description

~167752 4FIELD: This invention relates to the field of apparatuses in which a piston in a cylinder is advanced to 6 force contents of the cylinder out of the cylinder. More 7 specifically it is in the field of drywall construction 8 apparatus incorporating a cylinder and piston with the g piston being mechanically advanced to force contents of 10 the cylinder out of the cylinder. Still more specifically 11 it is in the field of automatic tapers used in drywall 12 construction, such automatic tapers having a cylinder and 13 a piston in that cylinder mechanically advanced to 14 dispense taping compound known as mud onto a joint between 15 drywall panels being taped.
16 PRIOR ART: The direct prior art to the subject in-17 vention is found in the automatic tapers marketed by Ames 18 Drywall Systems, Inc. in the United States and Concorde 19 Tool Company, Inc. in Canada. In such tools a roller 20 assembly at the dispensing end of the tool is pressed 21 against and rolled along the work surface. The roller 22 pulls tape off a roll of tape on the cylinder/handle of 23 the tool and a spool, clutch driven by the roller, reels 24 in a cable to pull the piston through the cylinder to 25 dispense mud onto the tape being applied. As the piston 26 comes near to the end of the cylinder, mechanism 27 declutches the spool from the roller and intermediate ~16~752 1 drawing mechanism so that the cable will not be strained 2 or broken when the piston can move no farther. Service 3 records of these tools clearly indicate that the piston 4 advance mechanism is unduly prone to fail and/or malfunction and that time and cost to service and repair 6 the mechanism are undesirably high. Also, the amount of 7 piston advance and resultant quantity of mud dispensed per 8 unit of travel of the taper head is not adjustable.
g Accordingly, the prime objective of the subject invention 10 is to provide a piston advance mechanism for automatic 11 tapers which is more durable and easier and less costly to 12 service than conventional piston advance mechanisms.
13 Another objective is that the mechanism be adjustable to 14 control the ratio of piston advance to advancement of the 15 taper in use.

18 The subject invention is a piston advance mechanism 19 for automatic tapers. The spool of the conventional head 20 assembly of an automatic taper is replaced by a two throw 21 crankshaft. The crankshaft is driven by the roller 22 assembly by chain and sprockets with no clutch needed be-23 tween the crankshaft drive sprocket and the crankshaft.
24 There is a connecting rod on each throw and each connect-25 ing rod is attached to a rod which extends the length of 26 the cylinder of the taper, parallel to the centerline of 27 the cylinder. Both rods extend through a piston assembly.

1 Each rod is interconnected to the piston assembly by a one 2 way clutch mechanism which operates such that axial 3 displacements of the rod can only move the piston assembly 4 toward the head end of the cylinder. As the crankshaft is rotated by rotation of the roller the rods are 6 reciprocated 180 out of phase with each other and the 7 rods alternately engage the piston and move it toward the 8 head end of the cylinder. One end of a rod extends from g the head end of the piston assembly and a crossbar at the 10 other end of the rod is positioned to engage the clutch 11 mechanisms and render them inoperative. When the piston 12 assembly approaches the head end of the cylinder the rod 13 contacts the head of the cylinder and is deflected to move 14 the crossbar to disengage the clutches so that the piston 15 assembly is driven only far enough to empty the cylinder.
16 The cylinder is refilled through a port at the head 17 end and the piston assembly must be disengaged from the 18 rods as it moves along the cylinder and rods as the 19 cylinder is filled. This disengagement is achieved as 20 follows: The rods have square cross-sectional shapes and 21 pass through square openings in cylindrical bushings in 22 the piston assembly. The faces of the bushings facing the 23 clutch mechanisms are specially shaped cams. Rotating the 24 rods rotates the cams such that they engage the clutch 25 mechanisms and hold them disengaged. The rods extend 26 through a bulkhead at the non-head end of the cylinder and 27 are geared together. A lever extends radially from one ~1677S2 1 gear and moving that lever rotates both rods 90~, 2 disengaging the clutches to permit free movement of the 3 piston assembly for loading the cylinder.
4 A preferred clutch mechanism comprises a plate in the shape of a rectangular block with a cylindrical hole 6 through it normal to the broad faces of the block. The 7 rod runs through the hole with slight clearance between 8 the block and the four corners of the rod. The block is g pivoted at one of its ends to fixed structure attached to 10 the basic part of the piston assembly. When the block is 11 cocked on the rod it locks to the rod and a spring around 12 the rod holds the block cocked and in the engaged state.
13 Motion of the rod relative to the block in the direction 14 of the spring force reinforces the engagement of the 15 clutch and carries the piston assembly with it. Motion of 16 the rod in the other direction disengages the clutch and 17 allows the rod to move through the piston assembly.
18 Pivoting the block against the spring force disengages the 19 clutch and the crossbar and cams described above pivot the 20 block to disengage the clutch.
21 There are pivotal connections near or in the 22 connections of the connecting rods to the advance rods to 23 allow the advance rods to turn without rotating the 24 connecting rods. The gears and lever which rotate the 25 rods are carried in journals in the bulkhead and the rods 26 slide axially in the gear hubs.
27 In a preferred embodiment, to provide adjustment of 1 the ratio of piston travel to roller travel, a lever 2 mechanism is installed between the connecting rods and the 3 crankshaft. One end of each lever is pivoted to fixed 4 structure and their other ends engage the throws on the crankshaft so that rotation of the crankshaft causes the 6 rods to swing reciprocally on their pivots. The wrist 7 pins of the connecting rods engage slots in the shanks of 8 the levers. Adjustment mechanism is provided to adjust g the location of the wrist pins in the slots. Moving the 10 wrist pins toward the pinned ends of the slots reduces the 11 reciprocating stroke of the rod and moving the pins toward 12 the crankshaft ends of the levers increases the strokes of 13 the rods.
14 The invention is described in more detail below with 15 reference to the attached drawings.

18 FIG. 1 is a sketch of an automatic taper to 19 illustrate the general configuration.
FIG. 2 illustrates the head assembly of an automatic 21 taper.
22 FIG. 3 illustrates the drive mechanism for the piston 23 advancement rods.
24 FIG. 4 illustrates the piston assembly.
FIG. 5 illustrates the rod actuation mechanism for 26 disengaging the clutches in the piston assembly.
27 FIG. 6 schematically illustrates mechanism providing 216775~

1 adjustability of the ratio of piston advance distance to 2 roller travel.

The subject invention is a piston advance mechanism 6 for an automatic taper. FIG. 1 illustrates an automatic 7 taper 9, comprising a cylinder assembly 10 which serves as 8 a handle for the taper and a head assembly 11 from which g the tape and compound known as mud are dispensed. A roll 10 of tape is carried on hub 12 on the cylinder assembly.
11 FIG. 2 illustrates the head assembly 11 in more detail.
12 In use the roller assembly 13 is pressed against and moved 13 along a surface, causing the roller to turn and drive 14 sprocket 14 which drives sprocket 15 via chain 16.
15 Referring to FIG. 3 sprocket 15 turns crankshaft 17 which 16 has throws 18 and 19 180 apart. Connecting rod 17 assemblies 20 and 21 are attached to crank pins 22 and 23 18 at their crank pin ends 24 and 25 and to rods 26 and 27 19 respectively at their piston pin ends 28 and 29 by pins 30 20 and 31. As the crankshaft turns the rods are reciprocated 21 180 out of phase with each other. Rods 26 and 27 are 22 supported in bulkhead fitting 32 which is mounted in 23 cylinder 33 of the cylinder assembly. Assemblies 34 and 24 35 allow rods 36 and 37 to be rotated (for purposes 25 described later) independently of rods 26 and 27 while 26 transmitting tension and compression forces between the 27 rods connected to each assembly.

1 Rods 36 and 37 extend through the piston assembly 38 2 shown in FIG. 4. The piston assembly comprises carriage 3 39 which fits closely but freely in the cylinder 33, and 4 comprises portions 40 and 41 interconnected by keel portion 42. Cup seal 43 is held to face 44 of portion 40, 6 facing the head end of the cylinder, by plate 45 which, in 7 turn, is fastened to portion 40 by fasteners, fastener 46 8 being typical. Bushings 47 and 48 pass through the plate, g seal 43 and portion 40 in holes 49 and 50 (not visible in 10 this view) and are held in place by snap rings 51 and 52.
11 The rods pass through the bushings, clutch plates 53 and 12 54 and holes 55 and 56 in portion 41 of the carriage 39.
13 The clutch plates are supported from posts 57 and 58 14 extending from portion 41 by links 59, 60, 61 and 62.
15 Springs 63 and 64 force the plates to rock on the linked 16 connection until the peripheries of holes 65 and 66 17 contact the corners of the rods. With this arrangement, 18 when either rod moves in the direction indicated by arrow 19 A, i.e. toward the head assembly, the clutch plate 53 or 20 54 on that rod 36 or 37 will engage the rod and the piston 21 assembly will move with the rod. When the rods move in 22 the direction away from the head assembly, the clutches do 23 not engage. In this way reciprocation of the rods 24 produced by rotation of the crankshaft causes the piston 25 assembly to advance toward the head assembly. When the 26 piston assembly approaches bulkhead fitting 34, end 67 of 27 rod 68 which extends through hole 69 in the plate, the ~167752 1 seal and portion 40 of the carriage, contacts the bulkhead 2 fitting. Crossbar 70 is attached to the other end of rod 3 68. When the reciprocating rods tend to move the piston 4 assembly closer to the bulkhead fitting, rod 68 is pushed, pushing the crossbar which in turn pushes the clutch 6 plates to disengage them from the reciprocating rods. In 7 this way the piston assembly is automatically disengaged 8 from the reciprocating rods when the cylinder is almost g emptied of mud.
To disengage the piston assembly from the rods for 11 purposes of refilling the cylinder the rods are rotated by 12 mechanism explained below, turning bushings 47 and 48 with 13 them. Faces 71 and 72 (not visible in this view) are 14 shaped such that when they are rotated a designated amount 15 they engage the clutch plates to hold them disengaged from 16 the rods. The piston assembly is then free to move 17 through the cylinder as mud is pumped into the cylinder in 18 front of the piston assembly.
19 FIG. 5 illustrates the mechanism for turning the 20 rods. Gears 73 and 74 are mounted in cylinder bulkhead 75 21 on their hubs, hub 76 showing in this view, the hubs being 22 retained in holes in the bulkhead, hole 77 showing in this 23 view, by snap rings, snap ring 78 showing. The rods 24 extend through and reciprocate in holes 79 and 80 in the 25 gears. Lever 81 is attached to gear 74 so that moving the 26 lever from the position indicated in solid lines to that 27 indicated in phantom lines provides the rotation of the 21677~2 1 rods needed to engage and disengage the piston assembly 2 from the rods, recognizing that each gear drives a rod 3 rotationally because the square cross-sectional shaped 4 rods engage the square shaped holes 79 and 80 in gears 73 and 74.
6 FIG. 6 is a schematic diagram of mechanism for 7 activating the rods which allows adjustment of the amount 8 of movement transferred to the rods from the crankshaft.
g Crank pin 82 engages slot 83 in lever 84 which is pivoted 10 at 85 to fixed structure 86. Connecting lever 87 is 11 pivoted to advance rod 88 at 89 and, by pin 90, engages 12 slot 91 in lever 84. End 92 of lever 87 is pivoted to 13 link 93 at 94 and link 93 is pivoted on block 95 at 96.
14 Block 9S is threaded onto screw 97 which is attached to 15 and is rotatable in hole 98 in structure 86. It is 16 considered to be understandable from this diagram that 17 moving block 95 along screw 97 by turning the screw will 18 adjust the amount of linear motion transmitted to rod 88 19 by a turn of the crankshaft. Raising block 95 (in this 20 view) decreases the travel of the rod. Lowering the block 21 increases the travel.
22 It is believed to be understandable from the above 23 description that the subject invention meets its 24 obiectives. It provides a durable piston advance 25 mechanism for automatic tapers which can be easily and 26 inexpensively serviced. Also, the mechanism can be made ~1677~2 1 adjustable to control the ratio of piston advance to 2 advancement of the taper in use.
3 It is also considered to be understood that while 4 certain embodiments of the invention are disclosed herein, other embodiments and modifications of those disclosed are 6 possible within the scope of the subject invention which 7 is limited only by the attached claims.

Claims (2)

1. In an automatic taper having a piston, a mechanism for advancing said piston in said automatic taper, said taper further comprising a head assembly having a roller assembly and a cylinder assembly having a cylinder, said cylinder having a length, said piston being part of a piston assembly movable in said cylinder, said mechanism comprising first and second rods supported in said cylinder and extending lengthwise in said cylinder and through said piston assembly, means for reciprocating said rods lengthwise in said cylinder, toward and away from said head assembly, said means for reciprocating being driven by said roller assembly, said piston assembly further comprising clutch means which are mechanically disengagable and automatically engage to connect said piston assembly to said first and second rods when said rods are moving toward said head assembly, said mechanism further comprising means for mechanically disengaging said clutches when said piston assembly is advanced close to said head assembly and further mechanical means for disengaging said clutches such that said piston assembly is free to move through said length of said cylinder.
2. The mechanism of claim 1 in which said first and second rods reciprocate a distance for each revolution of said crankshaft, said mechanism further comprising means for adjusting said distance.
CA002167752A 1996-01-22 1996-01-22 Piston advance mechanism for automatic taper Expired - Fee Related CA2167752C (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CA002167752A CA2167752C (en) 1996-01-22 1996-01-22 Piston advance mechanism for automatic taper

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CA002167752A CA2167752C (en) 1996-01-22 1996-01-22 Piston advance mechanism for automatic taper

Publications (2)

Publication Number Publication Date
CA2167752A1 CA2167752A1 (en) 1997-07-23
CA2167752C true CA2167752C (en) 1999-02-23

Family

ID=4157402

Family Applications (1)

Application Number Title Priority Date Filing Date
CA002167752A Expired - Fee Related CA2167752C (en) 1996-01-22 1996-01-22 Piston advance mechanism for automatic taper

Country Status (1)

Country Link
CA (1) CA2167752C (en)

Also Published As

Publication number Publication date
CA2167752A1 (en) 1997-07-23

Similar Documents

Publication Publication Date Title
US7222708B2 (en) Clutch actuator
CA2133858C (en) Reversing drive
US20110219626A1 (en) Drill attachment
US5611243A (en) Piston advance mechanism for automatic taper
CA2167752C (en) Piston advance mechanism for automatic taper
GB2088319A (en) Labelling apparatus
EP0145322B1 (en) Automatic slack adjuster for vehicle brakes
EP2747943B1 (en) Apparatus for tightening threaded fasteners
US20090314809A1 (en) Ejection device
CS590889A3 (en) Mechanism with various working methods for the control of rotary driving gear
DE4236267A1 (en)
GB2054361A (en) Device for cutting out and transporting a silage block
US4403523A (en) Reversible stepping actuator
CA1078230A (en) Tool for rotating nuts, bolts and like fasteners
US4015692A (en) Automatic slack adjuster
CN101326602B (en) A device for transmitting rotary motion and application thereof
CA1225055A (en) Ribbon feed mechanism for printer
US2562613A (en) Over-center lever actuated clutch
US4987794A (en) Stroke adjusting apparatus for a punching press
US4440034A (en) Eccentric vibrator with shifting coupling
US4556127A (en) Railway track lubricator
CN114206531A (en) Lever-driven cutting device
EP3752366A1 (en) Cutter module mechanism
US3714837A (en) Indexible clutch mechanism
US6300692B1 (en) Linear actuator with expansion device

Legal Events

Date Code Title Description
EEER Examination request
MKLA Lapsed