Vacuum Brakes

It is becoming increasingly important in the interests of safety that passenger-carrying trains should have good automatic (fail safe) brakes. As on full size railways the two main choices are between Vacuum and Compressed Air. Both have advantages and disadvantages. 

Compressed Air:
Advantages; high air pressure means only small brake cylinders are required which can easily be fitted into small spaces on vehicles. Air leaks usually easy to trace.

Disadvantages; air pump (compressor) always required. Pressure vessels required for reservoirs. Pressure connections required on all pipe work.

Vacuum:
Advantages; on steam engines vacuum can be created by a very small ‘ejector’.  No pressure vessels required for reservoirs. Pipe work and connections can be simple plastic push on fittings.

Disadvantages: on none ejector fitted locos a vacuum pump is required. Low air pressure means relatively large brake cylinders (actuators) are required which may be awkward to site. Leaks can be difficult to find.

Because of its inherent simplicity and since most miniature railways and model engineering societies have steam engines, the popular choice is the vacuum system.