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PRM 1500S Gearbox 3.01:1 SAE3, PRM1500S

PRM 1500S Shallow Case Marine Gearbox | Ahead Ratio 3.00:1 | SAE3

Part No. PRM-1500S30SAE3

6138 You pay €8,691.41 Incl VAT You pay €7,242.84 Excl VAT

RRP €12,071.40 €10,059.50

Save €3,379.99 (28.0%) Save €2,816.66 (28.0%)


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Brand PRM
Country of Origin United Kingdom
Gearbox Manufacturer PRM
Construction High Grade Cast Iron Gearcase
Hydraulic or Mechanical Hydraulic
Gearbox Model PRM 1500S
Ratio Ahead / Stern 3.00:1
Shaft Arrangement Drop Centre
Nominal Power Rating Pleasure 18.93 BHP / 100 RPM
Nominal Power Rating Light Commercial 17.52 BHP / 100 RPM
Nominal Power Rating Heavy Commercial 15.77 BHP / 100 RPM
Approximate Dry Weight 260kg (570lbs) (excluding drive coupling & cooler)
Capacity Oil Capacity: 8.0 litres (14 pints) (plus the amount required to fill the cooling circuit)
Certification / Approvals Lloyd's approved published ratings
Warranty (Years) 2


The PRM1500S series marine transmissions are the ideal choice for pleasure and commercial craft applications with engines rated at up to 520 hp (390 kW).

The PRM 1500S gearbox is the shallow case gearbox - with reduction ratios ranging from 1.22:1 to 3.0:1. Each PRM1500S marine gearbox is supplied with integral SAE housings as standard.

All PRM1500S series gearbox transmissions feature a twin countershaft design compatible with left or right hand propeller rotations - making them equally suitable for both single and twin engine installations. In addition, the PRM1500 two-stage reduction gearing enables maximum input torque of 1500 Nm to be transmitted continuously in either direction at engine speeds of up to 2500 rev/min.

Simple Operation

Gearbox operation is by a single lever compatible with proprietary remote control operating systems.

The need for special purpose automatic transmission fluid is eliminated by the use of engine oil specification lubricant.

Smooth drive gear engagement in both ahead and astern is achieved by a pressure modulated selection valve - ensuring outstanding boat handling and manoeuvrability.

Durable and Reliable

PRM1500 gearboxes carry a Lloyd's approved published ratings and utilise maintenance-free oil-operated, self-adjusting multi-disc clutches for consistent reliability and in-service performance.

The gear case is manufactured from high grade cast iron and is internally ribbed for extra rigidity and strength.

The oil pump, oil filter and hydraulic control valve on all PRM1500 gearbox models are mounted externally for easy access and servicing.

PRM 1500S Optional Equipment

Two optional clutched power take offs - compatible with SAE classification hydraulic pumps - are available to drive on-board machinery. Further ancillary equipment for PRM1500 gearboxes includes an oil pressure gauge, oil cooler kit and electrically operated control valve - incorporating a trolling valve facility that allows propeller speeds to be varied down to zero. This is fully inter-changeable with the standard control valve and can be retrofitted in service.

Nominal Power Ratings - PRM1500 Shallow Case Marine Gearbox
Model Gear Ratios Pleasure Light Commercial Heavy Commercial
1500S12SAE3 1.22:1 21.06 15.70 19.65 14.65 18.28 13.63
1500S15SAE3 1.56:1 21.06 15.70 19.65 14.65 18.28 13.63
1500S19SAE3 1.94:1 21.06 15.70 19.65 14.65 18.28 13.63
1500S22SAE3 2.25:1 21.06 15.70 19.65 14.65 18.28 13.63
1500S24SAE3 2.45:1 21.06 15.70 19.65 14.65 18.28 13.63
1500S30SAE3 3.00:1 18.93 14.12 17.52 13.07 15.77 11.76

Maximum operating speeds, intermittent 3000 rev/min, continuous 2500 rev/min.

S denotes Shallow Case: manufactured only with integral SAE3 adaptor housings.

Note: These powers are expressed in BHP and kW per 100 rev/min engine speeds, and are measured at the engine flywheel. Gearbox ratings have been established to ensure the long, trouble-free life of the gearbox and should not therefore be exceeded.

Service Classification Definitions

Pleasure: limited to planning hull pleasure craft with a maximum of 500 hours operating time per year, of which not more than 5% should be at full engine throttle, with the balance of usage at 90% or less of full throttle. The use of PRM marine gearboxes according to this classification in any commercial boat, or in sport-fishing charter boats or long-range pleasure cruisers, is not approved.

Light commercial: planning or semi-displacement craft used in pleasure or commercial application may qualify for light commercial rating if annual usage is less than 1500 hours and full throttle operation is limited, with most operating time at partial throttle.

Heavy commercial: all displacement and semi-displacement craft used for commercial applications should be classified as heavy commercial duty. In this type of vessel (such as trawlers, purse seiners, lobster and crab boats, tugs, ferries, offshore supply boats etc.) the gearbox is expected to work at full governed engine speed. The power setting of the engine must be known and must be within the permitted heavy commercial rating of the gearbox.

Important Note

1. It is essential that the engine, transmission model, reduction ratio and propeller size are correctly matched so that the engine can attain its rated speed appropriate to the relevant service classification without labouring.

2. It is also necessary to ensure the torsional compatibility of the complete propulsion system from engine 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 to transmission components.

ASAP Supplies and PRM Marine Limited 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.

PRM 1500S Operating Pressure

Minimum - 2827kPa (410lb/in²), maximum 3100 kPa (450lb/in²). Two tapped holes, 1 hole 1/8" on the top and 1 hole M18 on the side of the valve block are provided so that a pressure gauge can be fitted if required. Gear selector is designed with modulated engagement for soft shift.

PRM 1500S Oil Cooling

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 two ½" BSP connections are provided on the valve block to allow it to be fitted. The size of the oil cooler required depends on a number of factors including the transmitted horsepower, operating speed, duty cycle, inlet water temperature and ambient temperature.

PRM1500S Propeller Thrust

Both ahead and astern thrust is carried by the output shaft taper roller bearings which are of ample capacity for all factory approved ratings.

Approximate Weight and Oil Capacity for the PRM 1500 gearboxes

Gearbox Type

Estimated Dry Weight Estimated Oil Capacity
PRM1500S (Shallow Case) 260kg (570lbs) 8.0 litres (14 pints)

Note: Gearbox weight excluding drive coupling and cooler.
Note: Oil capacity does not include the amount to fill cooling circuit.

We can supply all your requirements for drive plates, oil coolers, oil, flexible couplings and shaft couplings for the PRM1500 gearbox range. Please note that the choice of drive plate / coupling must be made by the engine manufacturer/boat builder to ensure vibratory torque levels within the driveline are kept to a minimum within the engine operating speed range. This is particularly important as PRM1500 uses two stage gear reduction.

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