GB2432191A

GB2432191A - Clutch mechanism for roller door drive

Info

Publication number: GB2432191A
Application number: GB0619590A
Authority: GB
Inventors: Paul Anthony Kurzok; Gerry Chang
Original assignee: STL MAN Pty Ltd; GUARDIAN ACCESS CORP
Current assignee: STL MAN Pty Ltd; GUARDIAN ACCESS CORP
Priority date: 2005-10-05
Filing date: 2006-10-04
Publication date: 2007-05-16
Anticipated expiration: 2026-10-04
Also published as: GB2432191B; GB0619590D0; ZA200608302B; NZ550306A

Abstract

A drive unit 10 for opening and closing a roller door comprises a motor, a roller door drive 14 mounted to a shaft 16 and a drive gear 96. The drive train includes a gear 86 controlled by a position controller 108 such that movement of the position controller 108 in a first direction causes the clutch to move in a direction perpendicular to the first direction to permit the clutch gear 86 to engage with or disengage from the drive gear 96. An intermediate face 54 of a rear chassis member 28 includes a heart-shaped slot 62. Heart-shaped slot 62 has a first part 64 and a second part 66. Rotation of gear member 86 causes rotation of the shaft 70. Gear member 86 acts as a clutch and is able to slide longitudinally relative to the shaft 70. Driven gear 96 includes inner teeth 100 that engage with projecting teeth formed on the rear surface of gear member 86. Position control means 108 interacts with gear member 86 and acts to control the position of gear member 86. A pin 132 is positioned within the heart-shaped slot 62. When cord 154 is pulled, pin 132 moves out of first part 64 of slot 62 and moves up either side of slot 62 towards intermediate part 68. When the retaining pin 132 passes part 68, biasing spring 52 pushes the retaining pin downwardly towards the second part 66 of slot 62 to retain the position control means 108 in a position such that the gear member 86 is disengaged from the driven gear 96.

Description

I.I... -1.

FIELD OP TEE INVENTION

The present invention relates to a drive unit for a roller door.

BACKGROUNIJ TO THE INVENTION

Roller doors are in widespread use. Roller doors are typically wound about a spindle or axle. The spindle or axle is nonnally mounted adjacent to an opening that is to be closed by the roller door. Rotation of the door about the spindle or axle causes the roller door to either unwind and close the opening or to wind up and open.

It is becoming more common to provide roller doors with motorised driveS units to facilitate opening and closing of the roller doors. Such drive wilts are typically operated by remote control, especially where the roller door is used as a garage door. In this fashion, a user of the roller door does not have to leave his or her vehicle to open or close the roller door. Drive units for opening and closing roller doors typically include a roller door drive which engages and causes rotation of the roller door about the spindle or axle.

The drive unit will also normally include a motor and a drive train to transmit drive flnm the motor to the roller door drive unit. In this fashion, operation of the motor can cause rotation of the roller door drive which, in turn, causes rotation of the roller door about the spindle or axle to thereby open or close the roller door.

Roller door drive units are typically also provided with a clutch mechanism or disengagement mechanism which allows the roller door drive to be disengaged from the motor. The clutch mechanisms or disengagement mechanisms are provided to enable the roller door to be manually operated in the event of a failure in the power supply to the motor **.* * or in the event ofa failure of the motor itself.

Throughout this specification, the term "comprising" and its grammaticnjly variance, shall be taken to have an inclusive meaning unless the context indicates otherwise.

* : 25 BRIEF DESCRIPTION OF TEE INVENTION

* In a first aspect, the present invention provides a drive unit for opening and closing a roller door comprising a motor, a roller door drive fbr engaging with the roller door and rotating the roller door to open or close the roller door, a drive train for transmitting drive from the motor to the roller door drive such that operation of the motor causes rotation of the roller door drive, the drive train including at least one component moveable between a driving position in which drive is transferable from the motor to the roller door drive upon operation of the motor and a disengaged position in which the roller / door drive is disengaged from the motor, and a position controller being selectively actuable to move the at least one component from the drive position to the disengaged position, wherein operation of the position controller causes the position controller to move in one direction and causes the at least one component to move in a direction generally perpendicular to the one direction to thereby move the at least one component between the driven position and the disengaged position.

Preferably, the position controller moves along an iznaginaiy plane and movement of the position controller causes the at least one component to move in a direction generally perpendicular to the imaginaiy plane.

In one embodimcn, the position controller includes a ramp member moveable within a housing of the drive unit, the ramp member engaging with the at least one component and wherein actuation of the position controller causes the ramp member to move relative to the at least one component such that the ramp member engages with and moves the at least one component in a direction, that is generally perpendicular to the one direction.

Suitably, the position controller is biased to a position in which the at least one component is in the driven position. The position controller may be biased by the use of appropriate springs.

:.. In one embodiment, the position controller includes the ramp member and the , 20 ramp member is slidably movable within the housing.

The position controller is preferably manually operable by a person or *.... operator. The position controller may be operated, for example, by a person or operator pulling on a cord, a rope or a lever.

* The drive unit may further include retaining means for retaining the at least * : 25 one component in the disengaged position. The retaining means may act by retaining the *****.

* position controller in a position in which the at least one component is retained in the disengaged position.

In one embodiment, the retaining means may comprise a slot which receives a projection mounted to or in engagement with the position controller, said slot having a first part and a retaining part wherein the position controller is in the driven position when the projection is located at the first part and the position controller is in the disengaged position when the projection is located at the retaining part, wherein the retaining part is located closer to the first end than a most distant part of an intermediate portion of the slot.

In one embodiment, the slot is in the form of a heart-shaped slot. In another embodiment, the slot is in the form of a generally C-shaped slot.

In one embodiment of the present invention, the at least one component may include a gear member having teeth that engage with a driven gear. The driven gear may be driven either directly or indirectly by the motor. The gear member is preferably slidably mounted to a shaft, which shaft also forms part of the drive train. The gear member is suitably slidably mounted to the shaft in a manner which causes the shaft to rotate with the gear member. This may be achieved, for example, by use of appropriate key ways between the shaft and the gear member. The gear member may engage with the position controller such that actuating the position controller causes the position controller to move the gear member along the shaft to a disengaged position in which the gear member disengages from the drive gear moving the position controller to the original or biased position may also cause the position controller to move the gear member back along the shaft such that the gear member is moved to a position in which it engages with the driven gear.

In a second aspect, the present invention provides a drive unit for opening and closing a roller door comprising a motor, a roller door drive for engaging with the roller door and rotating the roller door to open or close the roller door, a drive train for transmitting drive from the motor to the roller door drive such that operation of the motor *** 20 causes rotation of the roller door drive, the drive train including at least one component moveable between a driving position in which drive is transferable from the motor to the *S..

S roller door drive upon operation of the motor and a disengaged position in which the roller door drive is disengaged from the motor, and a position controller being selectively actuable to move the at least one component from the drive position to the disengaged position, **I*..

* 25 Wherein the drive train includes a shaft having the at least one component slidably mounted **.* * * thereon and actuation of the position controller causes relative slidable movement to occur between the shaft and the at least one component.

The shaft may support a cog at an end located away from the driven gear which cog engages with the roller door drive. Suitably, the cog may be a toothed cog that engages with teeth which form part of the roller door drive.

In a third aspect, the present invention provides a drive unit for opening and closing a roller door comprising a motor, a roller door drive for engaging wth the roller

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door and rotating the roller door to open or close the roller door, a drive train for transmitting drive from the motor to the roller door drive such that operation of the motor causes rotation of the roller door drive, the drive train including at least one component moveable between a driving position in which drive is transferable ftum the motor to the roller door drive upon operation of the motor and a disengaged position in which the roller door drive is disengaged from the motor, a position controller for moving the at least one component between the driving position and the disengaged position and retaining means for selectively maintaining the position controller in a position at which the at least one component is in the disengaged position, the retaining means comprising a slot and projection extending into the slot, said slot having a first part at which the position controller is positioned such that the at least one component is in the driving position and & second part that retains the position controller in a position at which the position controller positions the at least one component in the disengaged position, wherein the slot includes a path of travel that extends from the first position to beyond the second position and back to the second position.

?rekrably, the slot is formed in a housing of the chive unit wherein a chassis member mounted in the drive unit However, it will be appreciated that the slot may also be on the position controller.

Preferably, the projection comprises a projection mounted to, formed with or **.. 20 engaging with the position controller. **I.

The slot may be a symmetrical slot. The slot may comprise a generally heart-shaped slot. Alternatively, the slot may comprise a generally c-shaped slot.

* BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a perspective view of a drive unit for a roller door in accordance * 25 with an embodiment of the present invention; *.**e * * Figure 2 is a rear perspective view of the drive unit shown in figure 1; Figure3 is afront view ofthe drive unit forarollerdoorshown irifigure 1; Figure 41s a side view of the drive unit for a roller door shown in figure 1; Figure 5 is a perspective view of a chassis arrangement positioned within the drive unit for a roller door shown in figure 1; Figure 6 is a perspective view from another angle of the chassis arrangement shown in figure 5; Figure 7 is an exploded view of the chassis shown in figures 5 and 6; Figure 8 is a cross-sectional view of the chassis shown in figures 5 to 7 with the drive train being in the driving position; Figure 9 is a cross-sectional view of the chassis shown in figures 5 to 7 with the drive train being in the disengaged position; Figure 10 is a front view of the chassis shown in figures 5 to 7; and Figure ii isasideviewofthechassjs shown infigures5to7

DETAILED DESCRIPTION OF THE DRAWINGS

It will be appreciated that the drawings are provided for the purposes of illustrating a preferred embodiment of the present invention. Thus, it will be understood that the present invention should not be considered to be limited to the features as shown in the attached drawings.

The drive unit 10 shown in figures 1 to 4 comprises a housing 12. Housing 12 carries a roller door drive 14. As best shown in figure 4, roller door drive 14 is mounted toashaft 16. Shaft The roller door drive 14 comprises a toothed outer surface 18. Teeth 18 engage with a toothed cog 20. Toothed cog 20 forms part of drive train that is driven by a motor of the drive unit.

::::. The roller door drive 14 includes projections 22, 24 that engage with the **.. 20 roller door in a manner known to the person skilled in the art. Rotation of the roller door S...

drive 14 causes projections 22,24 to rotate and thereby rotate the roller door around its S...

*... spindle or axle. Depending upon the direction of rotation, this either unwinds the roller door to close the door or winds up the roller door to open the door. The housing 12 is typically designed to enable the housing to be easily mounted to a building, such as a garage. The *S*S*.

* 25 housing 12 also houses a number of other components that will be described hereunder. The S.....

* other components mounted within the housing include the motor and the drive train that operates to transfer drive from the motor to the roller door drive 14.

Turning now to figures 5 to 7, which show various views of a chassis arrangement and drive train arrangement incorporated within the housing 12 of the drive unit 10, the chassis arrangement 26 includes a rear chassis member 28. A front chassis member 30 having opposed walls 32,34 overlies the rear chassis member 28. Flange 35 and flange 37 on respective end walls 32, 34 of front chassis member 30 may be provided with holes 36, 38, 44, 46 to enable the hDnt chassis member to be secured to the housing.

Similarly, rear chassis member may be provided with holes, 40,42 to enable the rear chassis member to be secured to the housing. Appropriate screws are suitably used to fasten the front and rear chassis members to the housing.

The front chassis member 30 includes a small downwardly depending flange 48. Downwardly depending flange 48 has an ann 50 extending therefrom and a biasing spring 52 is fitted over arm 50. Although not shown in Figure 5, the arrangement of the downwardly depending flange 48, ann 50 and biasing spring 52 may be replicated on the other side of' front chassis member 30. This is most clearly shown in Figure 10.

The intermediate face 54 of rear chassis member 28 has an opening 56 fonned therein. Intermediate face 54 also includes two sliding guides 58, 60. Bach sliding guide comprises two parallel raised projections. Intermediate face 54 of rear chassis member 28 also includes a heart-shaped slot 62. Heart-shaped slot 62 has a 6Est part 64 and asecondpart. Ascanbe seen, thesecondpart66 is to closerto the first than an intermediate part 68, 68' of the slot 62. The reason for this shape will be explained in more detail hereunder.

The drive train components of the drive unit include a shaft 70. Shaft 70 has a section 72 of squared cross section that, in the assembled drive unit, extends through : *" opening 74 in front chassis member 30. This is most clearly shown in figures. The squared "S.

*... 20 section 72 of shaft 70 terminates in a circular boss region 76 which nestles in opening 74. S.'.

Again, this is more clearly shown in figures. In this fashion, opening 74 acts to seat and **e.

guide the rotation of shaft 70.

* . . Shaft 70 includes a region of enlarged diameter 78. Region 78 includes key ways 80,82 extending longitudinally throughout the extent of region 78. *5SS$

* * 25 The drive train of the drive unit further includes a gear member 86. Gear member 86 includes a central opening 88 having key way projections 90, 92 that, in use, engage with key ways 80, 82 on shaft 70. By virtue of this arrangement, rotation of gear member 86 causes rotation of the shaft 70 because gear 86 and shaft 70 are keyed together.

However, gear member 86 is able to slide longitudinally relative to the shaft 70.

The drive train fbrther includes a worm gear 94 which is rotated by the motor of the drive unit (not shown). The worm gear 94 may be rotated by the motor by using any f arrangement know to be suitable by the person skilled in the art. Worm gear 94 engages * * ____--. ..".

with driven gear 96 to thereby cause rotation of drive gear 96. Driven gear 96 includes outer teeth 98 that engage with the teeth of worm gear 94. Driven gear 96 also includes inner teeth 100. Inner teeth 100 engage with complimcntaiy shaped projecting teeth formed on the rear surface of gear member 86. The teeth on rear surface of gear member 86 are not S shown on figure 7 but a person skilled in the art will readily appreciate that the teeth on gear member 86 engage with inner teeth 100 such that when the driven gear 96 is driven by the motor, rotation of the gear member 86 occurs, which in turn causes rotation of shaft 70.

The squared end section 72 of shaft 70 has cog 20 mounted thereto (as best shown in figure 1). Thus, rotation of shaft 70 causes rotation of cog 20 which, in turn, causes rotation of miter door drive 14.

The gear member 86 includes a waisted portion 102. Waisted portion 102 has enlarged shoulder portions 104,106 located on either side thereof.

The drive unit 10 is also provided with a position control means 108.

Position control means 108 interacts with gear member 86 and acts to control the position of gear member 86. Position control means 108 includes edges 110, 112, the lower surfaces of which Sit in sliding guides 58, 60. The positio.n control means 108 also includes a housing 114 formed at the side thereof which housing 114 has an opening 116 at a front portion.

The positioncontroI means 108 is positioned such that the arm 50 of front chassis member :.. 30 extends into the opening 116 of housing 114, with biasing spring 50 being interposed * S d 20 there between. This is best shown in figures. A similar arrangement is suitable replicated ***.

on the other side of position control means 108. In this manner, the position control means 108 is biased away from flange 48.

The position control means has an opening H8-A-conjiccter 120 having opposed faces 122, 124 interconnected by web 126 is connected to the position control 0e. : 25 means 108 by placing the holes 128, 130 in the respective faces 122, 124 over opening 118 ****** * and inserting a pin 131 through the respective holes. In this fashion, connector 120 is pivotally mounted to position control means 108. A farther pin 132 is also positioned within holes 134, 136 of connected 120. In use, pin 132 sits in slot 62.

A U-shaped member 138 having side arms 140, 142 interconnected by an intermediate arm 144 is also connected to position control means 108. In particular, side arms 140, l42haverespectiveholes, 146, I48thatengagewithand edonlugs 150, 152 formed on position control means 108. The side arms 140, 142 of U-shaped member 138 are sufficiently long such that the intermediate arm 144 of u-shaped member 138 does not contact connected 120. 138.

The position control means 108 also includes a ramp 156, In particular, ramp IS6includcsopposedrsnpajms 158, 160. Opposodramparins 158, I6Oareinengagement with the shoulders 104, 106 formed on gear member 86.

In the position shown in figure 7, the lower most portion of ramp arms 158, are in contact with the rear shoulder 106 of gear member 86. This acts to forec the gear member 86 to a lower most position in which the lower teeth of gear member 86 are in engagement with the inner teeth 100 of driven gear 96. hi this position, drive from the motor is transmitted via the drive train to the roller drive door 14.

If cord 154 is pulled, the position control means 108 is caused to slide towards end 162 of the chassis arrangement. As the position control member 108 moves towards end 162, the ramp arms 158, 160 come into contact with upper shoulder 104.

Continued movement of the position control means 108 towards end 162 causes the ramp arms 158, 160 to push the gear member 86 upwardly and away from driven gear 96. Gear member 86 slides up along the shaft 70 durIng this movement. This eventually causes the : .. lower teeth of gear member 86 to be moved out of engagement with the inner teeth 100 of a.

**, 20 drIven gear 96. In this position, the gear member 86 cannot transmit any drive from the motor as it is effectively disengaged from the driven gear 96. Thus, in this position, the * .**. overall drive train is in a disengaged position.

As mentioned above, pin 132 is positioned within the heart-shaped slot 62.

When the position control member 108 is in the position sho*iiifigure 7, the pin 132 rests : 25 in the first part 64 of slot 62. ft will be appreciated that biasing spring 52 assists in * :: maintaining the sprIng 132 in first part 64. When cord 154 is pulled to cause the position control means 108 to move towards end 162, the position control means 108 moves against the force of the biasing spring. There are occasions when it will be desired to maintain the drive train in the disengaged position. The arrangement of the slot 62 allows for this. In particular, as the position control member 108 starts moving towards end 162, the pin 132 moves out of first part 64 of slot 62. The retaining pin, by virtue of being mounted in pivotally connected connector 120, can move up either side ann of slot 62 towards

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intermediate part 68 or 68' of the slot. The intermediate part 68, 68' represent the forward most extent of movement allowed by the slot 62. When the retaining pin 132 passes parts 68 or 68', the action of the biasing spring 52 pushes the retaining pin downwardly towards the second part 66 of slot 62. It will be appreciated that second part 66 represents a localised minima in the extent of the slot 62. Thus, the combination of the shape of the slot 62 and the action of the biasing spring 52 acts to maintain the pin 132 in second part 66 of slot 62.

This, then, acts to retain the position control means 108 in a position such that the gear member 86 is disengaged from the driven gear 96.

U it isdesired to re engage the drive trainwjth themotor thecord 154 is again pulled which acts to cause movement of the retaining pin 132 from the second pan 66 of the slot 62 to the intermediate part 68 or 68'. The cord 154 may then be released and the action of the biasing spring 52 then causes the position control means 108 to return to the engaged position.

The movement of the position control means 108 and the gear member 86 fromtheegagedothedjsengagedpooflj$ nfigurcs8and9 Jnfigure8, the gear member 86 is in the engaged or driven position. As can be seen, the lower surface 87 of the teeth of gear member 86 are engagement with the inner teeth of driven gear 96. In figure 9, which shows the gear member 86 in the disengaged position, the lower surface 87 : of the teeth of gear member 86 are clearly out of engagement with the inner teeth 100 of *.... 20 driven gear 96. Thus, the shaft 70 can freely rotate without engaging with the driven gear 96 se..

because gear member 86 is disengaged from driven gear 96. As also shown by figures 8 and 9, the upward movement of the position control means 108 (that is, upward as shown in figures 8 and 9) causes the gear member 86 to move in a direction that is transverse and essentially perpendicular to the plane of movement fTh 108.

The roller door drive unit of the present invention provides a robust and reliable drive unit that enables compact construction and a neat finish.

Figures 11 and 12 show other views of the chassis arrangement which is shown in exploded or disassembled form in figure 7. In figure 11 and 12, the replication of the flange 48, ami 50, biasing spring 52 and housing 114 on both sides of the chassis arrangement is clearly shown.

Those skilled in the art will appreciate that the present invention may be susceptible to variations and modifications other than those specifically described. For * ._._.___._.____--.. * example, the heart-shaped slot may be replaced by a "c-shaped slot" or even by a slot that is effectively a half of the heart-shaped slot 62.

It is to be understood that the present invention encompasses variations and modifications other than thOse specifically described. * S. *. . **.. * S S... * I

S..... * S

I

S.....

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S..... -11 -

Claims

The claims defining the invention are as follows: 1. A drive unit for

opening and closing a roller door comprising a motor, a roller door drive for engaging with the roller door and rotating the roller door to open or close the roller door, a drive train for transmitting drive from the motor to the roller door drive such that operation of the motor causes rotation of the roller door drive, the drive train including at least one component nioveable between a driving position in which drive is transferable from the motor to the roller door drive upon operation of the motor and a disengaged position in which the roller door drive is disengaged from the motor, and a position controller being selectively actuable to move the at least one component from the drive position to the disengaged position, wherein operation of the position controller causes the position controller to move in one direction and causes the at least one component to move in a direction generally peipendicular to the one direction to thereby move the at least one component between the driven position and the disengaged position.

2. A drive unit as claimed in claim 1 wherein the position controller moves along an imaginary plane and movement of the position controller causes the at least one component to move in a direction generally perpendicular to the imaginary plane.

3. A drive unit as claimed in claim I or claim 2 wherein the position controller includes a ramp member moveable within a housing of the drive unit, the ramp member engaging with the at least one component and wherein actuation of the position controller causes the ramp member to move relative to the at least one component such that the ramp member engages with and moves the at least one component in a direction that is : s", generally perpendicular to the one direction. S...

4. A drive unit as claimed in claim 3 wherein the position controller S...

includes the ramp member and the ramp member is slidably movable within the housing.

5. A drive unit as claimed in any one of the preceding claims wherein * : *" the position controller is biased to a position in which the at least one component is in the driven position.

*:: 6. A drive unit as claimed in any one of the preceding claims wherein : : the drive unit further includes retaining means for retaining the at least one component in the disengaged position.

7. A drive unit as claimed in claim 6 wherein the retaining means comprises a slot which receives a projection mounted to or in engagement with the position controller, said slot having a first part and a retaining part wherein the position controller is in the driven position when the projection is located at the first part and the position controller is in thc disengaged position when the projection is located at the retaining part, wherein the retaining part is located closer to the first part than a most distant part of an intermediate portion of the slot.

8. A drive unit as claimed in claim 7 wherein the slot is in the form of a heart-shaped slot or a generally C-shaped slot.

9. A drive unit as claimed in any one of the preceding claims wherein the at least one component includes a gear member having teeth that engage with a driven gear, the gear member being slidably mounted to a shaft; which shall also forms part of the drive train, the gear member engapjng with the position controller such that actuating the position controller causes the position controller to move the gear member along the shaft to a disengaged position in which the gear member disengages from the driven gear.

10. A drive unit as claimed in claim 9 wherein moving the position controller to the original or biased position causes the position controller to move the gear member back along the shaft such that the gear member is moved to a position in which it engages with the driven gear.

11. A drive unit for opening and closing a roller door comprising a motor, a roller door drive for engaging with the roller door and rotating the roller door to open or close the roller door, a drive train for transmitting drive from the motor to the roller door drive such that operation of the motor causes rotation of the roller door drive, the drive train * 1 including at least one component nioveable between a driving position in which drive is ::f::: transferable from the motor to the roller door drive upon operation of the motor and a disengaged position in which the roller door drive is dsengag -from-the--motor, and a * * 25 position controller being selectively actuable to move the at Least one component from the **** * : drive position to the disengaged position, wherein the drive train includes a shaft having the at least one component slidably mounted thereon and actuation of the position controller causes relative slidable movement to occur between the shaft and the at least one * *. * component.

12. Adriveunftasclaimedjncjajm 11 wherein the shaft supportsacog at an end located away from the driven gear which cog engages with the roller door drive.

13. A drive unit as claimed in claim 12 wherein the cog is a toothed cog that engages with teeth which form part of the roller door drive.

14. A drive unit for opening and closing a roller door comprising a motor, a roller door drive for engaging with the roller door and rotating the roller door to open or close the roller door, a drive train for transmitting drive from the motor to the roller door drive such that operation of the motor causes rotation of the roller door drive, the drive train including at least one component moveable between a driving position in which drive is transferable from the motor to the roller door drive upon operation of the motor and a disengaged position in which the roller door drive is disengaged from the motor, a position controller for moving the at least one component between the driving position and the disengaged position and retaining means for selectively maintaining the position controller in a position at which the at least one component is in the disengaged position, the retaining means comprising a slot and a projection extending into the slot, said slot having a first part at which the position controller is positioned such that the at least one component is in the driving position and a second part that retains the position controller in a position at which the position controller positions the at least one component in the disengaged position, wherein the slot includes a path of travel that extends from the first part to beyond the second part and back to the second part.

15. A drive unit as claimed in claim 14 wherein the slot is present in a housing of the drive unit.

16. A drive unit as claimed in claim 14 wherein the slot is on the position controller.

: ,** 17. A drive unit as claimed in any one of claims 14 to 16 wherein the * * * * projection comprises a projection mounted to, lbrzned with or engaging with the position **.* controller.

*:::: 25 18. Adriveunitasclalnedinanyoneofc1ajms l4to l7whereintheslot * .* comprises a generally heart-shaped slot or a generally C-shaped slot.

19. A drive unit as claimed in any one of the preceding claims wherein * * the position controller is manually operable by a person or operator.

20. A drive unit as claimed in claim 19 wherein the position controller is operated by a person or operator pulling on a cord, a rope or a lever.

21. A drive unit substantially as hereinbefore described with reference to the accompanying drawings.