LIVE PTO

Modern boats, not just fishing craft and workboats but also pleasure craft, increasingly demand auxiliary power for driving on-board machinery such as winches, pumps or compressors. The traditional method of meeting these requirements has been to take an auxiliary drive from the front of the main propulsion engine, which involves expensive and space consuming vee-belt installations.

PRM500, PRM750 and PRM1000 marine transmissions now offer you compact, low cost and efficient alternatives: a choice of clutched or direct drive power take-off units which bolt directly to the rear face of the gearbox, either as factory fitted options or as assemblies for retro-fitting to existing gearbox installations. Both versions are specifically designed to drive hydraulic pumps, whether of the gear, vane or piston type; they are not intended to be adapted for driving an outrigger pulley since the mounting

Direct Drive Power Take-Off

Available on the PRM500 and PRM 750 the direct drive power take-off is driven directly from the gearbox input shaft; consequently it will operate at all times when the engine is running, and since there is no clutch for disengagement of the hydraulic pump, provision must be made in the auxiliary hydraulics circuits for pressure by-pass to the reservoir when power to the pump is not required. A pair of 1:1 ratio gears, providing sufficient offset between the gearbox output shaft and the centreline of the power take-off to ensure there is sufficient clearance between the hydraulic pump and propeller shaft coupling.

Capacity

All power take-offs are specifically designed for driving hydraulic pumps to SAE J744C series 'B' specification with splined input shaft and either two-bolt or four-bolt fixing. The maximum power which can be transmitted is 22 KW (29.5 bhp) per 1000 rev/min engine speed; this equates to a torque of 209 Nm (155 Ibf.ft. - 21.33 kgm.).For PRM1000 the clutched power take-off gives pump rotation the same as the engine, where as the direct drive power take-off for the PRM500 and PRM750 will give opposite rotation. Power to the pump is not affected by the normal use of the gearbox for propulsion duties. All ancillary power circuits driven by PRM power take-offs should be designed in accordance with the recommendations of the hydraulic equipment manufacturer, and should be properly safeguarded against overloading.

PRM power take-off units fit on the rear face of the main gearcase and are driven by the input shaft; consequently they can be operated at all times whilst the engine is running, The power take-off replaces the end cover which is normally fitted and performs the functions of the end cover by sealing the gearbox against loss of oil and correctly positions the input shaft rear bearing. Power take-off units also provide the link between the gearbox and the hydraulic pump.

PRM1500

Full hydraulic operation drop centre output shaft with two stage reduction gearing.

PRM1500 series marine transmissions are the ideal choice for pleasure and commercial craft applications with engines rated at up to 520 hp (390 kW).

They are available in both shallow and deep case form - corresponding to reduction ratios ranging from 1.22:1 to 3.0:1 and 3.12:1 to 4.9:1 respectively - and are supplied with integral SAE housings as standard.

All PRM1500 series transmissions feature a twin countershaft design compatible with left or right hand propeller rotations - making them equally suitable for both single or twin engine installations. In addition, the PRM1500's 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.

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

PRM1500 units 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 gearcase 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 models are mounted externally for easy access and servicing.

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.

PRM1750

Full hydraulic operation, drop centre output shaft with two stage reduction gearing.

PRM1750 series marine transmissions are the ideal choice for pleasure and commercial craft applications with engines rated at up to 620 hp (463 kW).

They are available in both shallow and deep case form - corresponding to reduction ratios ranging from 1.22:1 to 3.0:1 and 3.12:1 to 4.9:1 respectively - and are supplied with integral SAE housings as standard.

All PRM1750 series transmissions feature a twin countershaft design compatible with left or right hand propeller rotations - making them equally suitable for both single or twin engine installations. In addition, the PRM1750's two-stage reduction gearing enables maximum input torque of 1750 Nm to be transmitted continuously in either direction at engine speeds of up to 2500 rev/min.

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.

PRM1750 utilises a maintenance-free oil-operated, self-adjusting multi-disc clutches for consistent reliability and in-service performance.

The gearcase 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 PRM1750 models are mounted externally for easy access and servicing.

Two optional clutched power take-offs - compatible with SAE classification hydraulic pumps - are available to drive on-board machinery. Further ancillary equipment for PRM1750 gearboxes includes an oil pressure gauge, oil cooler kit and trolling valve.

PRM1000

Full hydraulic operation: offset or down angle output shaft.

The PRM1000 marine gearbox is purpose built for use in both pleasure craft and commercial boats; its twin countershaft design provides separate oil-operated multi-disc clutches (which need no adjustment) for ahead and astern drive allowing full rated power to be transmitted continuously in either direction.

To cater for the widest possible variety of boats the PRM1000 is offered either with output shaft, offset or 10°down angle output shaft. Reduction ratios available are 1.53:1, 2.03:1, 2.86:1, and 4.00:1 (4.00:1 reduction is not available on down angle gearbox) all of which can provide either left-hand or right-hand propeller rotation in "ahead", making the gearbox particularly well suited to twin engine installations.

The gearcase is constructed of high grade cast iron, internally ribbed for rigidity and strength, and consists of two separate halves to facilitate servicing, the oil pump and hydraulic control valves being externally mounted for easy accessibility.

The hydraulic operating system functions on normal lubricating oil of the same viscosity as that used in the engine, 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 hydraulic failure the boat can be brought safely back to port. Access to this device is via a detachable cover located on top of the main gearcase

A special feature of the PRM1000 is the clutched power take-off which is available as an optional extra; this will power a hydraulic pump to SAE J744C type 'B' specification, thus providing an economical and space efficient means of driving on-board machinery.

A Trolling Valve is also offered as an optional extra. This is electronically operated which allows variable speed of the propeller to zero whilst allowing a maximum engine speed of up to 1200 rpm.