PRM Hydraulic Marine Gearbox, Gear Ratio 1.94:1, Model A

Description

PRM750A Hydraulic Marine Gearbox, 8° Tilt Model, Gear Ratio 1.94:1

The PRM 750A Angle-Drive marine gearbox’s dual-shaft design and separate, identical friction plates for forward and reverse operation enable full rated power in both directions. The output shaft (flanged shaft) is angled at 8° and is 91 mm lower than the input shaft. The input shaft has a 17-tooth 16/32 DP spline.

Technical Specifications:

• reduction gear ratio: 1.94:1
• power rating (recreational use): 9.48 hp/100 rpm
• Power rating (recreational use): 7.62 hp/100 rpm
• Output shaft rotation direction when driving forward: RH or LH
• Input shaft splines: 17 TEETH, 16/32 DP
• SAE mounting: SAE2, SAE3, SAE4, and B/W plates available separately
• Maximum permissible instantaneous speed: 4,500 rpm
• Maximum permissible continuous speed: 4,000 rpm
• Weight: 90 kg
• Gearbox oil capacity: 3.0 liters + heat exchanger and hose volume
• Heat exchanger connections: 1/2" BSP x 16 DEEP

The gearbox’s hydraulic system quickly transfers the movement of the control lever to the friction plates, and the gearbox responds quickly to changes in direction, which is important for good boat handling.

Operation and Propeller Rotation Direction

The gear can be used with both clockwise and counterclockwise rotating propellers, making it particularly suitable for twin-engine installations. The housing is made of high-quality cast iron. The oil pump and hydraulic control valves are mounted externally for easy access.

The gearbox is extremely durable and reliable; it is also equipped with a mechanical locking device in the event of a hydraulic failure. In such a case, the transmission can be locked in the drive position, allowing the boat to be safely returned to port.

Operating pressure
Minimum – 30.34 bar (440 lb/in²), maximum – 33.44 bar (485 lb/in²). The top of the valve block has a 1/8" BSP hole, and the side has an M18x1.5 threaded hole for installing a pressure gauge, if needed.
Oil cooling
The normal operating temperature of the oil should be 50–80 °C, and the temperature must not exceed 90 °C. An oil cooler is required to maintain the correct operating temperature. The valve block has 1/2" BSP connections for installing the oil cooler.
Propeller Thrust
Both forward and reverse propeller thrust is transmitted to the output shaft bearings. The force exerted on the bearings is sufficient for all power ratings approved by the manufacturer.
Propeller Free Spinning
The output shaft of the PRM750A marine gearbox can rotate continuously when the gearbox is in neutral. Therefore, a propeller shaft brake is not required.
PTO (Power Take-Off)
The PRM750A model is available as an option with a direct-drive power take-off for a Type B hydraulic pump that complies with the SAE J744C standard. This feature thus provides a cost-effective and space-saving way to power the vessel’s hydraulic systems.