What kind of emergency release devices exist for spring-loaded brake cylinders?

You answered correctly. Spring-loaded brake cylinders have two types of emergency release devices: pneumatic and mechanical.

A pneumatic emergency release uses air pressure to release the spring-loaded brakes if they are stuck and cannot be released normally. A mechanical emergency release usually involves a special device or screw that physically relieves the spring’s pressure if compressed air is not available.

Automatic emergency releases do not exist for these systems. It’s important to know the difference, as this ensures you can handle emergency brake situations correctly and safely on the road.