A range of automatic overspeed air intake shut down valves which can also be automatically closed by an engine lubricating oil pressure (or air pressure) system to give shut down on loss of engine oil pressure, high coolant or high exhaust gas temperature. TMZ valves also are also supplied with manual start over-ride/manual emergency stop controls.

TMZ valves are available for all popular combinations of air intake pipe sizes and engine ratings up to 149 kW (turbocharged) or 179 kW (naturally aspirated). Some smaller TMZ valve sizes are optionally available with an integral intake flame trap housing and/or an integral engine air cleaner.

This type of valve may be fitted to either naturally aspirated or turbocharged engines. It should be noted however that for a given valve setting the repeatability of the actual shut down speed has a greater scatter in the case of a turbocharged engine. However, unless for special reasons a precisely repeatable shutdown speed is required, adequate protection from excessive overspeed and potential resulting damage is still achieved