Posted by Jack Rogerson 1 on 21/11/2010 07:20:41:
The latest idea for Model Aircraft engines, produced by O.S. who make some of the best engines in the world, is to use a brass liner, which is chromium plated. It is known as an ABC setup. (Aluminium piston. Brass liner .Chrome plated).The piston is aluminium and has no rings, but a very small groove wher the ring would normally be. This groove retains a smll ammount of oil, which helps lubrication.
The liner has a slight taper, being narrower at the top. The piston is a tight fit in the top of the liner, causing it to be pinched. When running, the liner heats up quickly and expands, allowing the piston to move freely. This also allows the liner to cool down, causing the piston to rub once more……..and so on.
Super Tigre was first to produce the ABC engines..
ABC in O.S.engines do not mean Aluminium, Brass, Chrome. Chrome are replaced with other word: Composite. Or in newer word ABN/ABL
O.S. Mfg. replaced the chrome plating with nickel plating about 15-20 year since . There are some disadvandages with nickel plating in O.S. engines , it will peel of the liner…
It is not much we can do with the plating in home workshop, not all folk has acess the plating equipments for home use.
The cast iron are good for the steam engines, the piston ring and liner will be made of cast iron. Both will run togheter without sign of abrasion when the steam engine are lubed with steam engine oil.
Edited By David Clark 1 on 21/11/2010 11:12:03