PRM marine gear ratio 1,96:1

Description

PRM260C In-Line Hydraulic Marine Gearbox, gear ratio 1.96:1

The transmission’s dual-shaft design and separate, identical friction plates for forward and reverse operation enable full rated power in both directions. The PRM260C input shaft splines are the same as those found in Borg Warner (Velvet Drive) 71C and Paragon P23 or P25 gearboxes.

Technical Specifications:

• gear ratio: 1.96:1
• power rating (light commercial use): 3.4 hp/100 rpm
• Output shaft rotation direction when driving forward: RH or LH
• Input shaft splines: 26 TEETH, 20/40 DP
• SAE mounting: B/W (Borg Warner) housing Ø 209.5 mm / PCD Ø 234.95 mm
• Maximum allowable instantaneous RPM: 4,500 rpm
• Maximum continuous RPM: 4,000 RPM
• Weight: 63 kg
• Gearbox oil capacity: 1.7 liters + heat exchanger capacity
• Heat exchanger connections: 3/8" BSP

In the PRM260C gearbox, the input shaft and output shaft are aligned (in-line model). The gearbox is also available with a 1.96:1 gear ratio.

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

The gear can be used with both clockwise and counterclockwise rotating propellers, making the PRM260C particularly well-suited 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 piloted back to port.

Operating pressure
Minimum – 18.27 bar (265 lb/in²), maximum – 22.06 bar (320 lb/in²). The top of the valve block has two 1/8" BSP threaded holes, and the side has an M18 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 be allowed to exceed 90 °C. An oil cooler is required to maintain the correct operating temperature. The valve block has two 3/8" BSP connections for installing an 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 PRM260C marine gearbox can rotate continuously while the gearbox is in neutral. Therefore, a propeller shaft brake is not required.