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Driving small sailboat and canal boat propulsion shafts, the 9 kg PRM PRM90-D2.5 mechanical marine reverse gearbox delivers a 2.5:1 offset reduction, handling 48 HP input at 5000 RPM reliably.
- 2.5:1 ratio drives canal boat propellers.
- Mechanical cone clutch eliminates hydraulic pumps.
- Input speed peaks at 5000 RPM.
- Oil sump takes 0.30 liters ATF.
- Lightweight casing weighs only 9 kg.
Managing small yacht and canal craft propulsion lines, the 9 kg PRM PRM90-D2 marine reduction gear transmission converts 48 HP input at 5000 RPM through an efficient 2.04:1 offset gear assembly.
- 2.04:1 reduction steps down engine speed.
- Offset parallel layout simplifies shaft alignment.
- Cone clutch provides smooth mechanical engagement.
- Continuous rating handles 15 HP diesels.
- Ultra-light unit weighs exactly 9 kg.
Tucked inside auxiliary sailboat engine bays, the 6 kg PRM PRM60-D2 mechanical marine reverse gearbox provides a 2.50:1 reduction ratio, taking 33 HP input at 5000 RPM on light dayboats.
- 2.50:1 ratio powers sailboat auxiliary lines.
- Mechanical clutch operates without hydraulic maintenance.
- Offset output configuration aids engine alignment.
- Internal reservoir takes 0.20 liters fluid.
- Miniature gear case weighs just 6kg.
Running high-speed river tenders and launches, the 6 kg PRM PRM60-D1.5 inboard boat transmission gearbox converts 33 HP input at 5000 RPM through a compact 1.52:1 offset reduction gear set.
- 1.52:1 reduction powers fast river tenders.
- Input speed handles up to 5000 RPM.
- Mechanical cone clutch ensures crisp shifting.
- Offset output design saves engine space.
- Ultra-compact chassis weighs only 6 kg.
Driving commercial displacement cruiser shafts, the 12.5 kg PRM PRM125-D3 mechanical marine reverse gearbox handles 70 HP input at 5000 RPM with a 3.06:1 offset reduction setup.
- 3.06:1 reduction matches displacement cruisers.
- Parallel offset output simplifies shaft installation.
- Mechanical cone clutch engages without hydraulics.
- Sump capacity holds 0.40 liters ATF.
- Compact lightweight casing weighs 12.5 kg.
Managing mid-sized fishing boat propulsion lines, the 12.5 kg PRM PRM125-D2.5 marine reduction gear transmission converts 70 HP input at 5000 RPM through a reliable 2.50:1 offset gear assembly.
- 2.50:1 ratio powers small tugboat propellers.
- Input speed peaks at 5000 RPM.
- Mechanical clutch provides dependable manual shifting.
- Continuous rating handles 23 HP diesels.
- Sturdy gear casing weighs 12.5 kg.
Bolting straight to compact diesel engines, the 12.5 kg PRM PRM125-D2 inboard boat transmission gearbox steps down 70 HP at 5000 RPM with an efficient 2.04:1 parallel reduction ratio.
- 2.04:1 ratio drives mid sized yachts.
- Offset parallel layout saves engine room.
- Cone clutch operates without hydraulic maintenance.
- Lubrication reservoir takes 0.40 liters fluid.
- Lightweight chassis weighs exactly 12.5 kg.
PRM Marine Transmissions & Reduction Gearboxes
Drop a PRM marine transmission into your vessel layout to handle intense engine shaft torque and secure smooth hydraulic gear engagement under continuous commercial duty cycles. PRM manufactures world-class hydraulic marine gearboxes, drop-center reduction gears, and multi-disc power take-offs engineered specifically to handle commercial workboat schedules, high engine RPM inputs, and raw saltwater scale exposure. Fleet operators, blue-water cruising sailors, and commercial fishing crews depend on these robust gearboxes to transmit engine power to the propeller shaft efficiently without clutch slippage or housing distortion. Mulmarine.com supplies genuine PRM propulsion gear and overhaul component kits directly to marine mechanics and yards nationwide. Bypassing hidden broker markups ensures you complete your next drivetrain overhaul on budget.
Why Fleet Operators Specify PRM Hydraulic Transmissions
PRM gear assemblies maximize driveline efficiency through precision-ground helical gears and heavy-duty multi-plate clutch packs running off internal oil pumps. Installing one of these premium units stabilizes your transmission performance when bolted to high-torque diesel blocks.
- Multi-plate hydraulic clutches deliver positive, zero-slip power transfer under continuous full-throttle commercial operations.
- Get-Home mechanical locking mechanisms allow captains to lock the gears into forward drive manually if hydraulic oil pressure drops completely.
- Twin-countershaft designs accept full rated engine horsepower in both ahead and astern directions, allowing identical performance on twin-screw hulls.
- Rugged cast-iron housings resist structural flexing and handle high thermal oil loads next to commercial inboard marine engines beds.
Why Settle Your Drivetrain Needs with Mulmarine.com
A slipping clutch pack or a leaking rear oil seal grounds your commercial charter vessel instantly, freezing your daily maritime operations and cutting off cargo revenue. While generic industrial parts warehouses lack marine-certified reduction gear boxes, we maintain physical warehouse inventory of genuine PRM gearboxes, friction plates, and replacement gaskets. Whether you are running a routine seasonal marine engine maintenance schedule or replacing a leaking oil cooler marine pumps circuit, we ship your drivetrain gear the same day to eliminate your drydock installation delays and protect your central marine gearbox setup.
What is the operational purpose of the manual mechanical lock feature on a PRM hydraulic marine gearbox?
The manual mechanical lock feature (often called a “get-home” device) is an emergency safety mechanism that allows a captain to lock the internal clutch packs together mechanically using basic tools if the transmission experiences a total loss of hydraulic oil pressure due to a pump failure or blown line. In standard hydraulic gearboxes, a loss of oil pressure causes the internal clutches to separate instantly, leaving the vessel stranded without propulsion. The PRM mechanical lock bypasses the hydraulic loop entirely, locking the engine shaft directly to the output propeller line to allow you to limp safely back to port under your own power.
How often should you replace the hydraulic oil filter element inside a PRM transmission housing?
Replace the hydraulic oil filter element and drain the transmission oil sump every 500 operating hours or at least once a year during routine seasonal maintenance servicing. You must drain the fluid while the gearbox is warm to ensure suspended contaminants drain out completely, check the magnetic plug for steel flakes, and refill the casing with standard engine oil as indexed in the manual. Running a hydraulic transmission with a clogged filter drops internal oil pressures below active clutch engagement thresholds, leading to rapid plate friction wear, overheating, and total gear failure.