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PRM 150 Gearbox 2.83:1 Ratio, PRM150

PRM 150D Drop Centre Marine Gearbox | Ahead Ratio 2.83:1

Part No. PRM-150D3

795 You pay £954.00 Incl VAT You pay £795.00 Excl VAT

RRP £1,359.60 £1,133.00

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Brand PRM
Country of Origin United Kingdom
Gearbox Manufacturer PRM
Construction Heavy Duty Aluminium Gearcase
Hydraulic or Mechanical Hydraulic
Gearbox Model PRM 150D
Ratio Ahead / Stern 2.82:1
Shaft Arrangement Drop Centre
Nominal Power Rating Pleasure 2.10 BHP / 100 RPM
Nominal Power Rating Light Commercial 1.50 BHP / 100 RPM
Nominal Power Rating Heavy Commercial 1.50 BHP / 100 RPM
Approximate Dry Weight 21kg (46lbs) (excluding drive coupling, adaptor flange & oil cooler)
Capacity Oil Capacity: 1.4 litres (2.5 pints) (plus the amount required to fill the cooling circuit)
Gearbox Spline 10 teeth B10 x 23 x 29mm DIN 5464
Gearbox Coupling 4", 4 holes, 3-1/4" PCD, 2-1/2" female register
Warranty (Years) 2


The PRM 150 Marine gearbox / transmission is purpose built for use with both pleasure craft and commercial boats; its twin countershaft design provides separate oil-operated multi-disc clutches (which need no adjustment) for ahead or astern drive allowing full rated power to be transmitted continuously in either direction.

The PRM 150 gearbox reduction ratios offered (1.53:1. 2.09:1 and 2.82:1) are all available for left-hand or right-hand propeller rotation in "ahead", making PRM150 gearbox particularly well suited to twin engine installations.

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

The PRM gearbox 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 PRM gearbox operating lever has a positive neutral detent and is suitable for use with proprietary single lever remote control operating systems.

Robust and reliable, the PRM 150 gearbox 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.

Nominal Power Ratings, PRM 150 Marine Gearboxes

Pleasure 2.1 BHP (1.6kW) per 100 rev/min operating speed
Commercial 1.5 BHP (1.1kW) per 100 rev/min operating speed
Max. Input Speed 5000 rev/min intermittent, 4500 rev/min continuous.

Note: These powers have been measured at the engine flywheel. Ratings have been established to ensure the long trouble free life of the gearbox which should not, therefore be used at powers in excess of those shown.

Service Classification Definitions - Pleasure

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.

Service Classification Definitions - Commercial

PRM Newage Ltd recommends that when considering the PRM 150 gearbox 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.

Important Note

  • It is essential for the engine, transmission model, reduction ratio and propeller size to be correctly matched so that the engine can attain its rated speed appropriate to the relevant service classification without labouring.
  • It is also necessary to ensure the torsional compatibility of the complete propulsion system from engine, gearbox through to propeller, since disregarding this may result in gear noise, particularly at low speed operation, and may even result in damage to the engine as well as the transmission components.

PRM Newage Ltd will provide all possible information and assistance to help find solutions to potential torsional problems, but it is the ultimate responsibility of the person assembling the drive and driven equipment to ensure that they are torsionally compatible.

Operating Pressure

Minimum - 2500 kPa (370 lb./in²), Maximum - 2850 kPa (420 LB/in²). A tapped hole ⅛" BSP is provided in the rear manifold so that a pressure gauge can be fitted if required.

Oil Cooling

The normal operating temperature of the gearbox 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 PRM150 gearbox is provided with two ¼" 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.

Propeller Free Wheeling

The PRM 150 gearbox 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 Weight & Oil Capacity

PRM150 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.

PRM150 Gearbox spline: 10 teeth B10 x 23 x 29mm DIN 5464
PRM 1510 Gearbox coupling: 4", 4 holes, 3¼" PCD, 2½" female register

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