GB2376054A

GB2376054A - Machinery pull cord

Info

Publication number: GB2376054A
Application number: GB0113010A
Authority: GB
Inventors: Steven Christopher Brandley
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-05-30
Filing date: 2001-05-30
Publication date: 2002-12-04
Also published as: GB0113010D0

Abstract

A pull cord of the type used for starting combustion engines on machines has a reinforced core within an outer sheath, which are preferably in sliding contact with each other. The core may comprise a metallic, polymeric or carbon material in the form of a wire, fibre, multi-stranded wire, yarn or multi-filament tow, cord or twine. The sheathing material may comprise polyester, polyamide, polyethylene, polyvinyl chloride, polyolefin, or natural and/or synthetic rubber and optionally contains particulate or fibrous fillers and/or reinforcing agents. The outer sheathing may be applied to the core material by extrusion coating, pultrusion, casting, moulding, shrink fit, wrapping, weaving or braiding of filaments around the core.

Description

MACHINERY PULL CORD This invention relates to an improved pull cord of the type for starting combustion engines on machines, such as small plant and tools from mechanical chain saws/ lawn mowers up to larger generators and practically any piece of mechanical equipment that is started by using a pull cord Pull cords are well known, but suffer from various disadvantages such as weakening and sudden breakage There are various elements that weaken standard pull cords such as A) extreme temperature change, B) exposure to various chemicals, fuel, concrete dust, and water etc, C) ageing, D) continuous use, and so on Another disadvantage is that often standard pull cords do not give much visible warning to when they may snap leaving a machine that cannot be started until a repair has been made The extremely rugged conditions encountered by equipment on a typical building site can include all of the above factors (A) to (D) and frequent pull cord breakage is a problem Although cords are not expensive, costs associated with idle machinery can be significant Conventionally pull cords are produced from polymeric materials including polyester and/or polyamide and may be constructed in a braid in an attempt to improve strength and abrasion resistance Oxidised polyethylene emulsion coatings and other coatings to improve wet and dry abrasion resistance have been described in the literature (see, for example, US Pat 4767646 (Allied Corp (US) 1988). Also changes to the design of the pull rope starter to reduce the quantity of dirt particles and abrasive dust settling in the cord slot (see US Pat 5627540 (Stihl (DE) 1993) have been described.

However, cord breakage remains a major problem and the single most common cause of equipment failure Thus, there remains a need for a pull cord with improved strength and abrasion resistance and which will provide a visual warning of incurring failure An object of this invention is to provide a pull cord that will not only have a sufficiently longer lifespan against all of the elements listed above, but will also give a greater amount of visible warning, long before any possible snap of the cord Accordingly, this invention provides a pull cord including a reinforced core within an outer sheath, such that the cord may be used on any existing machine that has been

designed to start using a standard pull cord 1-7

The core material is the major toad carrying component of the cord and may comptise a metallic material po) ymerie materia ! or carbon, preferably poiyetheretherketone, po) yara) r) id, poiyamide/imide, polyamide, poiyimide, po [ytetranuoroclhy) ene (I-'TFE), stecl, stainiess sieei, nickei, nickei-chrome, titanium, tungsten, atuminium and/or blends or alloys or carbon tow The core may be in the form of a wire, fibre, multistranded wire, yarn or multi-filament tow, cord or twine The core could comprise of I strand and/or up to 00 strands ranging from 0 0 ! mm diameter up to 3mm diameto but is preferahty of a multi-fiiament stainless steel wire having) 3 strands that make up a total combined outside diameter of i) mm and is optionaitv provided wit !) a coating ofpoiytetraluorocthyfene (PTFL) or other tubricious matenal or material having a iow coeHicient of friction The sheathing materia] IS cxternal to the central core and l11a\ he in intJl11ate contact with the core or tightly fitted to the core 01 being stiding contact with the COle iciill (-, coiitiict N'Itli tile C (-) Ie mater ial The sheathing materia ! maY be composed of pohcster polyamide, po1\'\'iml chioride, polyotefin, natural and/or synthetic rubber and ophonallv contains particulate or ibrous filiers and/or reinforcig agents T he sheathmg materiai ma\ be applied to the cote mate ! in) by extntsion coating, puitfusiol. casting, moukiitig, sinmk fit, wrapping, weaving or braiding ofHiaments around the core The sheathing materia) is prcferably of a polyamide and/or polyester braided construction that is in sfidmg contact with the cote materia) ('he putt cotd of the present in\ention) s 200 mm to IOOOO mm) ong, prcfoabiy oOO iiiiii to 1)-1 mm to 3000 mm iong. most ptcferabiy 000 mm to i300 mm tong The putl cord of the present invention has an overall diameter of) mm to t5 mm, prefcrabiv 2 mm to 8 mm, most preferably 3' : ; mm to 5 mm The inner core is I I mm diameter x () OU 111m long The outer sheathing is 3 i mm diametci \ 000 mm iong and may comptise onc I iaiiietci x 1) 00 to three lavers of materiai having a combination of desired properties such as oil and chemical tesistance, resistance to L'V light and resistance to abrasion in the otites lavera of the sheath at least A prefei-ed embodiment of the iventton \) t) now be described with teference to the accompanying drawmg) n which [T (} m < jL f shows a side \ie\ of a section of the cord with the temforcement shghtiv longer to give better understanding ofbuitd FIGURF 2 shows an end section of the cord showing inner and outer sections As shown in figurez the pu ! ! cord comprises an inner reinforcing core), being encased with an outer sheath 2 Figure 2 show's the same thing fi-om a diffeient angie, an inner remfot cement core I encased with the outer braiding 2 When the pull cord is mounted to a machine, it will be fitted in the same way as any normal pull cord would be fitted, one end having a knot tied then threaded through the handle, with the other end being fitted to the recoil as manufacturers specification

Once the correct length of pull cord has been selected for the specific machine, the pull cord is fitted accordingly to the machine in the same way you would fit a normal

pull cord, being very flexible the pull cord will pull out straight and wind round the starter recoil in the same manner as any normal pull cord A specific embodiment of the invention will now be described by way of the following non-limiting example Example A pull cord, comprising a 1 I mm diameter x 900 mm long stainless steel core within a 3 5 mm diameter x 900 mm long braided polyamide sheath to provide a loose sliding contact, was attached to a 2 stroke petrol driven cut off saw (the type that houses up to 300mm diameter blades) in the normal manner by knotting one end of the cord and threading through the handle with the other end fitted to the recoil according to the manufacturer's specification No alterations or adjustments to the cut off saw were required to allow the fitting of the pull cord The cut off saw was in constant daily use on a variety of building sites over a 5 month period without breakage The outer braiding looked very worn by the end of the 5 month period giving visible warning that the cord may need replacing but the cord was still functional in everyway, in comparison a conventional non-reinforced polyamide braided cord lasted 6 weeks before snapping without warning

Claims

Claims

) A puH cord of the type for starting interna) conbustion engines on machines I 1-1 illes including a reinforced core within an outer sheath, such that the cord may be used on i coie Nviiiiiii an OLItCl Sll any existing machine that has been designed to start using a standard pull cord 2 A puH cord as claimed in claim). where the sheathing material is externa ! to the central core and may be in intimate contact with the core or tightlv fitted to the core or being sliding contact with the core matoia) 3 A pn) ! cod as claimcd in ciaim 2, where the sheathing material is in shdmg contact with the core matetial 4 A puit cord as claimed in cianus) to 3. where the reinforcing core compnscs a metallic material, polymeric mateual or carbon 5 A puii cord as claimed in claim 4, where the reinforcing core in the form of a wire, fibre, muti-stranded wire yarn or multi-filament tow, cord or twine < 3 A putt cord as ciaimed in claims 4 or 5. where the feinfbicing coe comprises a mcta)) ic material. prcfclahfy steel. stail ess steef nickel mckci-chlome. titamum tmigsten, alumimum and/or blends or aiio\'s 7 A putt cord as ctaimed in claims 4 or 5. whetc the reini'orcmg core compnses a polymeric matettaf pteterabiypotyetheretherketone. potyatamidf potvamidc/tmide. poivamide. pol\'imide and/or potytetraHuotoethylene 1) o) Nliiiii (le, I) olN, Iiiilde aii (t/oi- 8 A pu)) cord as ctamed in ciaims 4 or 5. where the reinforcing core compnses a carbon materia). preferah) y carbon yarn or mu !lti-f) iament to\w cord ot twine l) i\ pull curd as c1aimed in claims 1 to : 1. \\hcre the sheathing materizd is applied to the cote inaten :al by extrusion coating, puttrusion. casting, mollding. sh) in) \ fit. wrappmg. wearing or braiding ot maments around the core 10 J\ pull cord as ctatmed in ciaims t to 3 whete the sheathing) natcria) comprises polyester, poiyamide, po) yethyienc, po) y\'iny) chtoride. pojyoieim. natura) and/or synthetic tubbet and optionatty contains parttcuiatc or fibrous finers and/or teinfofcing agents 7 il A pull cord as claimed in claims 2, () and 10, where the sheathing material is in the form a braid ] : 2 ; \ pull cord comprising : a stainless steel stranded \IvÍre core, optionall\'coated with poiytetranuoroethylenc (PTFE) having an outer sheath ot'braided f) bres

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13 A pull cord as claimed in claim 12, comprising a 0 5 mm to 1 1 mm diameter x

900 mm long stainless steel stranded wire core, optionally coated with I polytetrafluoroethylene (PTFE) having an outer sheath of braided fibres whereby the sheath has overall dimensions of 3 5 mm to 5 mm diameter x 900 mm long