GB2262931A - Extendable tower. - Google Patents

Abstract

An extendable tower comprises a number of cradles each consisting of telescopic sections having nylon guide rollers (B) and brass cable rollers (D) which can be erected by cables (C). Each cable has an individual tensioner. The tower comprises a triangular or quadrilateral arrangement of the above cradles with a platform between them. The cables are raised or lowered by a winch. <IMAGE>

Description

-- W O R K H O 1 S T BACKGROUND This invention relates to a hoist which allows the operator to work at infinitely variable heights in safety and comfort without the need to climb! Ladders, towers and indeed hydraulic cantilever hoists are established tools for working at various heights. This invention is a viable alternative to these structures.

Designed to be lightweight, therefore portable, (triangular version) it will fit into an average sized van.

On unloading the WORKHOIST the operator must attach mobility wheels, adjust the "level" on site, connect to power source and fit safety handrail. The hoist is then fully operative.

The telescopic and pulley features in this design make the WORKHOIST very efficient as a variable height load carrier.

Safety is of prime concern in the structure and its components.

Note: P/A is used in this design brief. It refers to 'PATENT APPLICATION'.

W 0 R K H O I S T -- ESSENTIAL TECHNICAL FEATURES 1. Two basic WORKHOIST formats are included in this P/A.

a) The lightweight or triangular 600 3 sided format.

b) The heavier or square 900 4 sided format.

2. Important Note In this P/A more detailed information will be given over the triangular 600 format. Many references will be made to the square 900 format, in fact both are based on the same desiqn only the number (quantity) of components differentiates the two, the components in both cases are the same.

3. The most important and innovative part of the design is that of the runners, and their configuration.

a) The runners are manufactured from extruded aluminium forming a box and channel cross section.

b) The runners also feature a double roller system.

A "guide" roller of durable nylon and a "cable" roller of brass.

c) The runners are designed in three distinct types: i) Inner or work platform runner ii) Intermediate double runner iii) Outer or fixed anchor runner d) A principle feature of the three types of runner is that they "interlock" to provide a safe stable mechanism designed to move vertically in a "telescopic" fashion.

3. (Contd.) e) Further to this is the cable system, which runs over and under the brass cable rollers to link all the runners from the inner to the outer and provide the source of lift to the whole structure.

f) Sets of "like" runners are linked together by use of welded support struts to form rigid "cradles" See Drawing No. 10 i) In the case of the triangular format hoist a set of 3 No. (three) "like" runners are used to form one cradle. (600 set) ii) In the case of the square format hoist a set of 4 No. (four) " like " runners are used to form one cradle. (900 set) g) Another feature is to the "inner" or work platform runner (c/i) which has built-in a cable termination point that can be adjusted individually to take up any cable slack due to stretching, and thus keep a balance between the individual cables in the structure. Triangular format hoist has 3 No. (three) cable sets, the square format has 4 No. (four).See Drawing No. 3 3. (Contd.) h) For the purposes of this design brief (Patent) the runners will be fixed dimensions (approx.

685 mm long x 25 mm wide x 37 mm deep and 685 mm long x 25 mm wide x 31 mm deep) and will form the triangular 600 format hoist with runners in set of 3 No. (three). However, the need for other sizes will of course be required when build subsequent hoists of a heavier/stronger construction that will access higher work locations and carry a heavier load, and will of course include the square or 900 format, but the principle design remains the same.

i) The main reason for this initial design restraint is to produce the lightest/smallest variation so as to allow access through a standard 30 inch door opening, but hoist to 6 metres.

j) Note:- The hoist will have to be stood on its "side" to pass through a 30 inch door opening.

4. POWER SOURCE AND RELATED FEATURES a) Power will come from an electric motor fitted with a suitable gearbox. These two items in conjunction will drive a cable winch or drum.

Initial specification for the motor will be:- 250 v - 50 cycles - single phase. 600 lbs MAX lift capability via a gearbox delivering approx. 50-60 R.P.M. The motor will be reversible. The motor, gearbox and winch will be located on the base plate underneath the inner or work / /.....

4. (Contd.) a) (Contd.) /..... cradle footplate. Lastly a dual braking system will be built-in to ensure greater safety under full load. This will be in the form of electro-magnetic motor brake + a manual re-set back-up. Ref. Drawing No. 12.

b) Two winches or cable drums are designed for this application.

i) 3 section drum for the triangular format.

ii) 4 section drum for the square format.

b) The cable drum will be attached and suitably braced to the gearbox. In the case of the triangular format hoist the 3 No. independent cables will be guided by rollers from the base of the outer or fixed anchor runners (See 3Ciii) to their own section on the cable drum. In the case of a square format hoist 4 No. cables will be used.

d) An anchor point will be provided on the cable drum for EACH independent cable.

e) An electro-mechanical switching arrangement will be attached to the winch and will provide a failsafe means of shutting down the motor at or before the hoist has travelled to its safe maximum extended point, and also its closed down or fully retracted point.

4. (Contd.) f) A self retracting cable (electrical cable) reel will be located alongside the motor assembly.

This will provide the moving work platform with switching cable used to operate the hoist from the attached foot switch. See Drawing No. 12.

Note F:- An alternative would be a permanently coiled cable say 4-5 inches dia such as used on telephones and extension leads etc.

5. A set of mobility wheels will be supplied with the following features a) Detachable from bottom of base-plate.

b) Height adjustable to allow levelling of hoist.

c) Swivel and roll double action brake.

d) A safe convenient storage point on the hoist for wheels when not in use.

e) Each wheel will have an approx. load capacity of 200 kg during use.

f) A set of 3 No. (three) wheels* will be supplied with the triangular format hoist and 4 No. (four) wheels* with the square format hoist.

* These wheels can be purchased "off the shelf" and will not be featured on this P/A.

6. SAFETY CRADLE AROUND OPERATOR A detachable safety cradle will be shown. It will attach to the inner cradle at designated points. The cradle will be approx. waist high or 915 mm. Also it will hold a work tray for use with the operator's tools, again waist high. When not is use the safety cradle assembly will store on WORKHOIST.

7. A simple flip down step will be located on the outer cradle. Function will be to simplify stepping in and out of the WORKHOIST before and after use.

Ref to Drawing Nos. 1 and 1A Pages 10-11 *All wall thicknesses a minimum 3 mm.

3Ci Inner Runner. Formed from extruded aluminium to form a box and channel cross section. I/D of box section 'A' is approx. 25 mm x 25 mm. This is about as small as is practical to form a 'runner'. There is no limit to how big this may be.

'Runner Guide Faces' are bearing surfaces and carry the load of the facinq nylon guide roller.

(25 mm I/D) 3Cii Intermediate Runner. As above (3Ci) but with notable difference. This runner contains two channel sections at 1800 to each other.

Dimensions are the same.

Channel Section 'B' is 25 mm x 6 mm I/D.

Runner Guide Walls. Locate and stabilise the nylon guide rollers which run in them. Nylon guide rollers are 0.5 mm narrower than the guide walls i.e. 0.25 mm each side this gives minimum working clearance, but maintains guide stability.

Ref Drawing No. 8.

3Ciii Outer or Fixed Runner (anchored). this is simply a mirror image of 3Ci but is shown separately to avoid confusion.

Runner Side Walls are used to support roller bearing bolts and also accept the support struts (welded) that form cradles.

Runner Back Wall. Always points away from next runner.

Ref to Drawing No. 2/Page No. 14 THE BRASS CABLE ROLLER is used to convey the cable from the inner runner through the nine intermediate runners to the final outer or fixed runner where the cable is then guided under the base plate to the motorised winch. See Drawing No.

13.

The diameter and depth of Groove 'B' is determined by the diameter of the cable to be used. In this P/A I am using a 2 mm dia cable with a breaking strain of 256 kg. Groove 'B' therefore will be 2.5 mm wide and 3 mm deep. This allows the cable 0.5 mm clearance on the width and ensures it will lay 1.0 mm below the O/D of the roller. Dimension 'G' or dia of the base of Groove is determined by the following formula: (dia of cable x 14) or 2mm x 14 = 28 mm. Dimension 'A' therefore is 28 mm + 6 mm - 34 mm.

Dimension 'C' is approx. 10 mm less than the width of the runner guide walls. (See Drawing No. 1) In this instance the guide walls are 25 mm apart (I/D) therefore 'C' = 15 mm.

This differential ensures the free unhindered running of the roller in use.

Bore size 'F' has been fixed at 10 mm dia, greater heights or loads would need this to be re-appraised. (See notes Drawing No. 2) But for this P/A it is sufficient to carry the loads I envisage for the lightweight triangular format hoist.

Ref to Drawing No. 2/Page No. 14 (Contd.) BRASS CABLE ROLLER (METHOD OF FIXING) * Fixing the roller to the runner is by use of a 10 mm dia shank high tensile steel bolt. The shank acts as the bearing surface and must be smooth and regular in finish. The bolt must be long enough to pass through from runner side wall to runner side wall and be locked off by a self locking nut. It may be prudent to include a 4 mm shim washer either side of the roller to avoid excessive lateral movement when in use.

* This same fixing bolt may be used with the following item:- HIGH IMPACT NYLON GUIDE ROLLER This item and its function is most important to the smooth operation of the runners, therefore great care must be taken when making and fitting them.

Dimension 'E' is 3 mm greater than Dimension 'A' on brass roller, 37 mm. Dimension 'D' is 0.5 mm narrower than the width of the runner guide walls 24.5 mm. Dimension 'F' has been dealt with.

When setting the two rollers into the runner they must be no more than 0.5 mm apart, see Drawing No. 4 Page 18. This ensures the cable never leaves its groove when in use or slack! Ref to Drawing No. 3/Page No. 16 'A' Is approx. 18 mm across the flats and is the means by which tension is adjusted to each cable using a standard ring spanner. Total length of bolt 'A' = 200 mm.

tst Is a brass bush set into the runner and centres the long bolt.

'B1' Is a hexagonal alleyn type bolt approx. 4 mm thread dia which is screwed in from the outside and locates all the separate components. PLEASE NOTE it does not come into contact or tighten against the shank of the bolt, merely retains it.

'C' Is the runner body. 665 mm long.

'D' A brass threaded bush which is brazed into brass tube 'G'. Also it is drilled and tapped to accept location pin/indicator 'E'.

location pin prevents 'D' turning when in use by passing out through body 'C'. It also doubles as an indicator of how much travel is available up/or/down.

'F' A long groove or slot approx. 4 mm wide and 125 mm long in which location pin 'E' travels.

'G' Is a brass tube approx. 22 mm O/Diameter and 150 mm long. It is used to connect D & by means of brazing and to give sufficient clearance to bolt 'A'.

'H' A brass end plug which forms the anchor point for incoming cable.

'I' Smooth elongated hole through which cable passes in loop fashion to be tied off using the clamped or crimped ferrule method.

Please note that location pin 'E' passes through runner body 'C' on the face known as 'Runner Back Wall'. See Drawing No.

1.

Ref to Drawing No. 4/Page No. 18 'A' Is equal to channel section 'B' on Drawing No. 1 and is not machined on any of the 3 types of runner.

'B' This clearance must be kept to approx. 0.5 mm so as to prevent the cable from jumping out of its groove on the brass cable roller.

'C' Refers to the milling away of 'runner guide faces' to accommodate the rollers. No swarfe or burrs should be left behind to obstruct the rollers. It is advisable to make the opening some 10 mm greater than the combined dia of both rollers plus the 0.5 mm gap 'B'.

Distance 'D' = 9.5 mm in all cases.

* Please note this drawing shows the base or bottom section of the previous Drawing No. 3 and is in the same plane or orientation.

* It is worth noting at this point that the total length of all runners shown in this P/A should not exceed 27 inches or 685 mm inclusive of all rubber stops, top caps or bolt heads Ref to Drawing No. 5/Page No. 20 'A' Top End Stop or Plastic Bung. Note is covers the channels on both sides offering a degree of protection.

'B' Nylon Guide Roller uppermost on the upper section.

'C' Refers to milled Runner Guide Faces. See Note 'C' Page No. 18 Drawing No. 4.

Shows position of Brass Cable Roller. Note the smaller dia of the roller compared to 'B'. This ensures the roller will run free and not bear against the runner guide face of the opposite runner.

Please note total length of runner including end stop and rubber end stop is 685 mm.

This is not the limit of the runners length but for this P/A I wish the TOTAL height of the completed WORKHOIST not to exceed 29 inches or 735 mm. This will mean when stood on its side the WORKHOIST will pass through a standard 30 inch doorway (excluding main wheels).

Ref to Drawing No. 6/Page No. 22 Details of upper section is much the same as given in Drawing No. 5, except that runner 3Ciii only has one channel section.

The lower section however differs. Firstly it is welded at exactly 900 to the base plate 'G'. Weld is indicated as 'F' on 3 sides of the runner excluding the channel face.

Brass cable roller 'D' is not paired with a nylon roller and is situated low enough to avoid the weld but to protrude through the base plate.

Clearance 'E' is about 0.5 mm and serves to keep the cable in its groove on the brass runner.

Distance 'H' is set at 17.5 mm. The O/Dia of roller is 34 mm thus giving 0.5 mm clearance.

'C' again is the milled section of the runner guide face and is approx. 40 mm in length. This allows the roller to be fitted or replaced after welding.

Ref to Drawing No. 7/Page No. 24 Point I, shows the bottom of tension adjuster fixed to runner 3Ci.

The cable is tied off with a suitably clamped ferrule E in the standard loop fashion. It then passes under 1st roller 'D' in the same runner.

Running inside the two adjacent channels it passes up and over roller 'D' in runner 3Cii then on down to roller 'D' inside the base of runner 3Cii then under and back up inside the two adjacent channels - (at this point it is worth noting that in practice several 3Cii runners would follow - See Drawing No. 8) - and over the top roller 'D' in runner 3Ciii, down inside to exit roller 'D' and out under base plate where it is guided via further rollers to the electric winch.

Also note how Guide Rollers 'B' interlock with opposite runners to form a stable vertical moving structure with little or no lateral movement due to the very close fit of nylon rollers into facing channels. See Drawing No. 8 to clarify this point.

'F' shows welding to base plate of runner 3Ciii.

Ref to Drawing No. 8/Page No. 26 'A' Note the series of high impact nylon guide rollers and how they bear against the facing 'runner guide face'. 'C' 'B' At the back edge of the roller not the clearance.

2mm is ample.

Also note 0.25 mm shims each side of the roller.

'E' Top view of the tension adjusting bolt attached to runner 3.c.i. See Drawing No. 3.

'F' Centre-line and point of fixing for bearing bolt and self locking nut.

Note the spacing of each runner from the facing runner. This should be a minimum of 2 mm and is governed by the set of the nylon guide wheel against the opposite runner guide face.

Ref to Drawing No. 9/Page No. 28 Schematic plan elevation showing how each runner, in this case 3Ciiis are linked using welded support struts to form a cradle.

Point 'A' = 300 set required to form the 600 triangular format hoist.

Point 'A' would be 450 on the square format hoist.

Point 'B' shows where welding to runner body takes place.

Point 'C' = support struts. On this Drawing the outer/fixed or 3Ciii runners are the furthest apart. Subsequently runners/cradles interlock (inside) this cradle, therefore struts will be proportionately shorter. Ref. Drawing No. 11.

Point 'D' "Runner Guide Face" for next intermediate runner to interlock into. (3Ciii).

Cross ref. to Drawing No. 10 shows side elevation of welded struts.

Ref to Drawing No. 10/Page No. 30 Point 'A' This distance is variable but its main object is to provide sufficient clearance for guide roller and cable roller fixing bolts or bearing bolts.

Point 'B' This distance is determined wholly by the number of intermediate or 3Cii runners/cradles located inside this outer 3Ciii. In this P/A we are using 9 No. (nine) intermediate cradles therefore this distance will be approx.

1.4 m.

Point 'C' This distance again is variable and is determined by actual dimension of runners. Also in this P/A I am restricting this distance in order that the total dimension of the finished WORKHOIST will pass through a 30 inch standard door opening i.e. 735 mm.

Note the lower horizontal strut is welded to base plate.

this is in order to keep the base plate as rigid as possible during use. Applies only to 3Ciii cradle (outer).

See Drawing No. 15 for X.

Ref to Drawing No. 11/Page No. 33 Plan view of the WORKHOIST showing all 11 No. (eleven) cradles in situ.

All three sides have support struts but for clarity only one side is shown with all struts.

Point 'A' X is the fixing point for main wheels. 3 No. (three) are shown on the triangular format. (4 No. (four) on square format).

Point 'B' Shows the outer fixed runner in relation to the rest. (3Ciii) Point 'C' Shows the inner or work platform runner in relation to the rest. (3Ci) Point 'D' Shows the 9 No. (nine) intermediate runners in relation to the rest. (3Cii) Point 'E' Support struts link all 'like' runners to form rigid interlocking cradles.

Point 'F' Base plate to which outer cradle is welded (3Ciii). Base plate also supports mechanical components such as motor etc.

Ref to Drawing No. 11/Page No. 33 (Contd.) Point 'G' Shortest outside dimension on the WORKHOIST in this P/A. It is likely to be approx. 1.3 m (51 inches).

Point 'H' Length of inner cradle supports will be approx. 500 mm.

Point 'I' Longest outside dimension on the WORKHOIST in this P/A. It is likely to be approx. 1.58 m (62 inches).

Point 'J' Operators footplate containing anti-slip treatment, and foot operated control switch.

* Note total floor area used by the WORKHOIST featured in this P/A is 1.04 m2 or 1.2 sq. yds.

Maximum platform height approx. 6.1 m or 20 ft. as featured in this P/A.

Ref to Drawing No. 12/Page No. 35 Schematic side elevation showing telescopic action. Only 5 No. sets of runners are shown in a two dimensional sketch, and without support struts to aid clarity.

A: Runner 3Ci - inner runner or work platform runner.

b: Runner 3Cii - intermediate runners C: Runner 3Ciii - outer or fixed anchor runner. (Note weld at base) D: Electric cable reel to feed both foot switch and motor.

(Auto rewind) E; Electro-magnetic brake assembly.

F: Reversible 250 v motor/gearbox.

P: Steel cable drum or winch pulley.

G: Limit & safety switchgear.

H: Handrail fixing points.

I: Foot switch.

J: Foot plate.

K: Clearance for D. - E. - F. - P. & G.

L: Multi-core electric cable.

Ref to Drawing No. 13/Page No.37 Schematic showing a row or set of runners of which there are 3 No. (three) making up the triangular WORKHOIST. (4 No.

(four) are used on the square format).

Featured is the cable route from the inner 3Ci runner, anchored at the tension adjuster (See Drawing No. 3), running out to the 3Ciii runner then via further guide rollers to the winch.

Point J Foot plate Point F Reversible motor/gearbox Point P Steel cable attaches to cable drum. Note the 3 No. (three) separate sections of the drum, one for each incoming cable.

(4 No. (four) cables on the square format) Point G Limit & safety switchgear Point H Handrail fixing point * Note I have not shown welded support struts in order to aid clarity. (See Drawing No. 10) Ref to Drawing No. 14/Page No. 39 The base plate assembly is manufactured to form a sandwich effect.l The base plate itself will consist of an aluminium sheet large enough to accommodate the WORKHOIST cradles (see Drawing No. 11) and approx. 4 mm thick.

Point B and A Attached around all three sides will be an aluminium 'C' shaped channel - Point B on Drawing. To attach the two parts a row of pop rivets will run the full length of the channel at intervals of approx. 100 mm - Point A on Drawing.

Point C and F An inspection cover - Point C on Drawing will be attached to the lower section of the channelling along line F using self tapping screws at 200 mm intervals. Only thin section material is required for the cover to minimise weight.

Point E The whole assembly forms a cavity - Point E on Drawing, through which all cables will be run to the winch assembly.

'E' will require to be approx. 40-80 mm.

Point D and G At the corners of the base plate on the underside will be welded into place at Point D an aluminium bracing plate.

This plate will carry or support the main mobility wheels (detachable).

Point G will be approx. 150 mm.

Ref to Drawing No. 15/Page No. 41 Featured is a simple flip down step which helps the operator to step up onto the WORKHOIST. It is intended to stow flat when not in use.

All aluminium construction the step will be hinged (brass) at Points H.

The 'T' support leg will rest on the base plate via a rubber end stop.

Distance A will be approx. 300 mm.

Back plate 'X' will be suitably fixed to the outer cradle support struts as indicated on Drawing No. 10 Point 'X'.

Dimensions of step are academic, but lets say 180 mm wide x 160 mm deep x 4 mm thick.

The top face of the step will have an anti-slip treatment.

Ref to Drawing No. 16/Page No. 43 Handrail Assembly (Plan Elevation) Point A Is a fixed handrail, and is simply dropped into fixing Points H.

Point J Foot plate.

Point B Is a fixed handrail as above but will also support a tool tray that simply clips on (not shown).

Point C Is a hinged handrail that may be opened like a gate to allow operator access to foot plate J.

Point C Should be positioned over step (See Drawing Nos.

10 and 15).

Point D Side elevation of detachable handrail showing fine mesh infill.

Top of Handrail D will be approx. 915 mm from foot plate J.

See Drawing Nos. 12 and 13.

Claims (1)

1. FEATURES/CLAIMS

   The WORKHOIST operates on two principle actions, the telescopic action of the interlocking runners/cradles stabilised by the many high impact nylon guide rollers, and the pulley action of the many cable guide rollers, which effectively 'gear down' the load making the WORKHOIST very safe.

   The use of 3 No. cables on the triangular format hoist and 4 No. on the square format hoist means the maximum load 600 lbs is below the real capacity of the WORKHOIST e.g. 1500 lbs.

   Independently adjustable cable tensioners for each cable means they can all be kept under equal tension, thus ensuring stable vertical lift.

   Compact and reasonably portable, (lightweight format) the WORKHOIST can be lifted out of a van by one fit man. Also the design, (triangular format) in this P/A allows the WORKHOIST to pass through a standard 30 inch doorway when taking advantage of the detachable main wheels.

   Apart from minor adjustments, such as fixing on main wheels and levelling the WORKHOIST, the hoist is designed to be ready for use straight off the van.

   The WORKHOIST is designed to allow the operator to 'ride' up and down from ground level to maximum height in safety and comfort. This means he DOES NOT have to climb or struggle with tools etc. when accessing high work locations.