The heavy duty aluminium alloy gearcase is internally ribbed for rigidity and strength and consists of two separate halves to facilitate servicing.

The hydraulic operating system functions on normal multigrade engine oil, avoiding the need to use automatic transmission fluid, and ensures rapid response to movements of the operating lever for good boat handling. The operating lever has a positive neutral detent and is suitable for use with proprietary single lever remote control operating systems.

Robust and reliable, the hydraulic system is nevertheless provided with a mechanical lock up device for added security, so that in the unlikely event of a hydraulic failure the boat can be brought safely back to port. Access to this device is via the detachable manifold on the rear of the gearcase which also houses the hydraulic control valve.

Minimum - 25.51 bar (370 lb./in²), Maximum - 28.96 bar (420 lb/in²). A tapped hole 1/8" BSP is provided in the rear manifold so that a pressure gauge can be fitted if required.

The normal operating temperature of the oil should be in the 50°C - 80°C range and should not be permitted to exceed 90°C. An oil cooler is necessary to ensure that correct operating temperatures are maintained, and the gearbox is provided with two 1/4" BSP connectors to allow it to be fitted. The size of the cooler depends on a number of factors including the transmission horsepower, operating speed, duty cycle, inlet water temperature and ambient temperature.

The PRM150 output shaft can be rotated continuously with the gearbox in neutral. It is therefore not necessary to fit a propshaft brake when running with the engine shut down, e.g. in multi-engine installations or when sailing.

Approximate dry weight: 21kg (46lb) excluding drive coupling, adaptor flange and oil cooler
Oil capacity: 1.4 litres (2.5 pints) plus the amount necessary to fill the oil cooling circuit.

Limited to craft used exclusively for pleasure boating; operation at full engine throttle should not exceed 5% of total time, with balance of usage at 90% of full throttle engine speed, or less. Maximum operation 500 hours per year. The selection of PRM150 according to this classification for any commercial boat is not approved by PRM Newage Ltd.

PRM Newage Ltd recommends that when considering the PRM150 in boats of whatever hull form used in commercial applications, and semi-displacement hull boats for pleasure applications, these boats should be classed as commercial duty and the gearbox selected accordingly.