These are usually rotary valves, or piston valves. This is an SOHC engine with two valves per cylinder. The injectors are cycled from the same camshaft responsible for opening the exhaust valves. It displaced and had five valves per cylinder. Trinity has intake valves and exhaust valves. INKO and the exhaust valves are marked EXKO. Physical compatibility requires the installation of hardened exhaust valves and seats. Single horns use a single set of tubes connected to the valves. Many of the complications associated with mechanical heart valves can be explained through fluid mechanics. Thrust control is by partially closing the electromechanical propellant valves. The backflow of urine is prevented by valves known as ureterovesical valves. The heart valves and the chambers are lined with endocardium. Steam traps are nothing more than automatic valves. Posterior urethral valves; urethral or meatal stenosis. See also the article Brass Instrument Valves.