Anglicky v odborných předmětech "Support of teaching technical subjects in English “

1. Anglicky v odborných předmětech"Support ofteachingtechnicalsubjects in English“ Tutoria:Engineering technology Topic:Chain gears Prepared by: Ing. Jaroslav Hábl Projekt Anglicky v odborných předmětech, CZ.1.07/1.3.09/04.0002 je spolufinancován Evropským sociálním fondem a státním rozpočtem České republiky.

2. Circuit 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 GEARS

3. ADVANTAGES OF CHAIN GEARS • Usability 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 drives • Drive possibility of several shafts by onechain ( angleofwrap is β < 90° ) CHAIN GEARS

4. DISADVANTAGES OF CHAIN GEARS • Quite high price • Noise of operation • Gear operation is not even within one revolution • Gear needs to be mounted on flat surface • Gear is not suitable for frequent machine revolutions´ reversal CHAIN GEARS

5. GEAR RATIO CHAIN GEARS

6. TYPES OF CHAINS • Roller 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 GEARS

7. TYPES OF CHAINS Ewart´s 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. Gall´s 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 GEARS

8. TYPES OF CHAIN Renold´s 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 GEARS

9. CONSTRUCTION OF CHAIN WHEELS The pitch of chain links imax = 8 for chains with links´ pitcht ≤ 9,525 imax = 6 for chains with links´ pitcht > 9,525 The most advantageous axis distance isa = 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 ≤ 9,525 z1 ≥19 for chains with links´ pitch t > 9,525 z1 < 17 only occasionally CHAIN GEARS

10. CONSTRUCTION OF CHAIN WHEELS Dimensions of chain wheels Relative dimensions CHAIN GEARS

11. CONSTRUCTION OF CHAIN WHEELS MATERIAL 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. CHAIN GEARS

12. Literature • Stroje a zařízení I, J. Doleček, P. Gajdoš, V. Novák • Strojnictví I, J. Doleček, Z. Holoubek • Strojnictví II, J. Doleček, Z. Holoubek • Moderní strojírenství, Josef Dilinger a kolektiv

13. How is circuit force transmitted at chain gears? • Name at least 3 types of chains. • How are chain wheels´ materials chosen?