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Anglicky v odbornch pedmtech"Support of teaching technical subjects in EnglishTutoria: Engineering technology

Topic: Chain gears

Prepared by: Ing. Jaroslav Hbl

Projekt Anglicky v odbornch pedmtech, CZ.1.07/1.3.09/04.0002je spolufinancovn Evropskm socilnm fondem a sttnm rozpotem esk republiky.

CHAIN GEARSCircuit force is transmitted by shaped contact from driving wheel to driven one and/or to tow bar - or to drive wheel from tow bar. These transmissions are used at technical, agricultural and construction equipment, at vehicles and hoists, at lines with continuous movement in series production, at escalators etc. They are suitable for continuous transmitting of torsional movement to intermediate distances.

CHAIN GEARSADVANTAGES OF CHAIN GEARSUsability at long shaft distances ( up to 5 m )High efficiency up to 98 %Smaller straining of shafts and bearings than it is common at belt drivesDrive possibility of several shafts by one chain ( angle of wrap is < 90 )

CHAIN GEARSDISADVANTAGES OF CHAIN GEARSQuite high priceNoise of operationGear operation is not even within one revolutionGear needs to be mounted on flat surfaceGear is not suitable for frequent machine revolutions reversal

CHAIN GEARSGEAR RATIO

CHAIN GEARSTYPES OF CHAINSRoller chain can have 2 types of pitch:- normal pitch for peripheral speeds over 12 ms-1 There can be single in-line, dual in-line, three in-line types.- long span for peripheral speeds to 6 ms-1 Construction can be as single row.

Capsule chain is produced in 2 versions:High-speed for speeds over 12 ms-1 Slow-speed to transmission of high forces at peripheral speeds to 3 ms-1

CHAIN GEARSTYPES OF CHAINSEwarts chain has links made of malleable iron. It is dismountable at slight turn of links by 90.Gear is noisy and inaccurate. It is used for speeds up to 1 ms-1 at carries and agricultural machines. Galls chain is used for large loading and speed to 0,5 ms-1. For example, it is the part of hoists and chain blocks, cranes, lifts etc. The number of chain chords is from 2 to 10.

CHAIN GEARSTYPES OF CHAINRenolds toothed chain is used for large loading and high speeds up to 30 ms-1. They must work in oil bath. Its operation is quiet. It is used for gear drive of combustion engines.

Lamella chain is made of several lines at steel belts attached to quenched pivots. Oval capsules come over belts where are wedge-shaped lamellas placed. Lamellas noses interlock into radial tracks of conical wheels that is why they transmit loading. They are used at disk friction drives.

CHAIN GEARSCONSTRUCTION OF CHAIN WHEELSThe pitch of chain links

imax = 8 for chains with links pitch t 9,525imax = 6 for chains with links pitch t > 9,525

The most advantageous axis distance is a = 40 t

The rim shape of toothed chain wheels is normalized. The number of wheels teeth of gearing should be odd and even so that wearing is equal.

For roller chains , the number of teeth is chosen in that way:z1 17 for chains with links pitch t 9,525z1 19 for chains with links pitch t > 9,525z1 < 17 only occasionally

9CHAIN GEARSCONSTRUCTION OF CHAIN WHEELSDimensions of chain wheels

Relative dimensions

CHAIN GEARSCONSTRUCTION OF CHAIN WHEELSMATERIAL OF CHAIN WHEELS

Material of chain wheels is chosen so that smaller wheel is harder than the bigger one because it works more often in operation. For more strained chain wheels, heat or chemically processed steels are chosen, low-strained wheels can be made of lower hardness steels and non-metal materials.

LiteratureStroje a zazen I, J. Doleek, P. Gajdo, V. Novk Strojnictv I, J. Doleek, Z. HoloubekStrojnictv II, J. Doleek, Z. HoloubekModern strojrenstv, Josef Dilinger a kolektiv

How is circuit force transmitted at chain gears?

Name at least 3 types of chains.

How are chain wheels materials chosen?