View non-flash version
Falk Gears Propulsion Update (Continued from page 53) the astern clutch. The locked shaft against the slipping clutch allows the engine to produce torque over a longer, more controlled duration, while mini- mizing clutch heat buildup. Figure 4 (on page 51) shows an exam- ple of the astern clutch engagement during a full-speed crash reversal of a tuna seiner using the engine torque-up system. In the example, engine speed is boosted to 500 rpm, and the astern clutch begins pressurization. The accelerating engine comes under load as the shaft brake remains engaged and the astern clutch begins to trans- mit torque. This initial load on the engine causes the fuel rack to increase the fuel rate to the engine, causing the turbochargers to begin pumping, increasing the torque output of the engine. As the shaft brake is released, the engine speed falls from 500 rpm to engine idle at 350 rpm, and the pro- peller shaft accelerates in the astern direction. With the turbochargers pumping, the engine is then developing sufficient torque to overcome the rever- sal. To overcome the high propeller back- torques in such a short period of time, the engine must be boosted to 580 rpm. As the clutch engages, the propeller shaft brake is released, prior to the torque transmission within the clutch. The propeller begins to accelerate in the ahead direction, driven by the entrained water within the wheel. As the engaging astern clutch begins to transmit torque, the propeller must be stopped and reversed. The engine struggles to produce sufficient torque, falls to 250 rpm and finally increases speed to complete the reversal. In a reversal of this type, the engine is loaded so abruptly, that the tur- bochargers do not begin to increase the engine torque output until well after the clutch has become fully engaged. This forces the engine to overcome the propeller back-torque while in the aspi- rated mode, causing the engine speed to fall well below idle speed, and possi- bly stalling and back-driving the engine. With the engine torque-up system, the reversal is completed with much less shock to the engine, clutch and other propulsion system components. The torque-up system also allowed the reversal to be completed in a much shorter time, and with a shorter time delay. For more information on the system Circle 36 on Reader Service Card Sea Yltfer Intake, Cooling System Designed for Overall Cost Savings (Continued from page 93) ously higher than the water flow rate to the pumps at 100 percent loading. Bottom Gratings: In the JAK-system, recommended openings (usu- ally 20 x 200 mm) cut directly on the bottom plate increase the net area. The total net area of the chest bottom is selected so that water flow rate through the openings is less than 0.1 m/s at 100 percent load- ing. On high-speed vessels, the openings should be located longitudinally to make it easier for the water to flow inside the chest. On icebreakers and other vessels operating in difficult ice conditions, the openings should be located transversely, as experi- ence gained from ice-breakers seems to indicate that the icy slosh is then compressed against the back edges of the openings allowing water to rise in the chest, as the flow rate is very low. JAK-system does not require docking as all the service and maintenance operations can be carried out from the inside at any time, and all the equip- ment can be lifted up from the chest. The JAK-sys- tem includes no valves, fittings or filters, and is free of holes below the maximum load line. For more information on Acomarin Circle 38 on Reader Service Card The preceding was excerpted from an article authored by Kari U. Laiho, managing director of Acomarin Engineering Ltd. LIQUIDATION SALE NOW IN PROGRESS! Manly Marine Closures are to outlast your vessel Since 1964 Manly closures have set the standard for quality. Call Manly for the following custom built products: MANLY DOORS • Dutch & wheelhouse • Aluminum & steel construction • Watertight doors, marine & construction • Joiner doors, B-15 fire rating • Airlock doors MANLY HATCHES • Escape • Access • Fish hold covers • Manholes MANLY WINDOWS Marine Closures Ltd.1 Model H70 Hatch M-10 Manhole, tapered coaming j Model D-022 Aluminum Solid Core Door Model D-062 Aluminum Plate Quick-Acting Door 20 Brooksbank Avenue P.O. 86788, North Vancouver B.C. V7L4L3 Canada Tel: (604) 984-4635 Fax: (604) 983-2713 March, 1997 Circle 214 on Reader Service Card $12,000,000 | INVENTORY OF m\ISlD SHIP BUILDING MATERIAL FOR SALE! Surplus to the ongoing operations of AVONDALE INDUSTRIES, INC. NEW ORLEANS, LOUISIANA $4,000,000+ of UNUSED ELECTRICAL MATERIAL, CABLE & ACCESSORIES * $2,500,000+ of UNUSED VALVES, FLANGES AND FITTINGS $2,500,000+ of UNUSED ASSORTED SHIP BUILDING COMPONENTS * $1,000,000+ of UNUSED FASTENERS: BOLTS • CLAMPS • SCREWS • ETC. *$ 1,000,000+ of UNUSED PIPE, TUBE, TUBE STUFFING & RELATED ITEMS $1,000,000+ of UNUSED HYD. FITTINGS, PLUMBING, AC/HEATING, HOSE * $1,000,000+ of UNUSED PLATE, SHEET, ANGLE, CHANNEL & BAR STOCK $100,000's of UNUSED WOOD, ROPE, WIRE, WIRE MESH & ROPE, ETC. * Consisting of: Aluminum • Brass • Chrome-Moly • Copper • CM* Galvanized • Monganese-Bronze • Monel ' NICU • Silicone-Bronze • Stainless • Carbon steel • etc. ACT IMMEDIATELY • SALE NOW IN PROGRESS • SUBJECT TO PRIOR SALE FOR MORE INFORMATION OR AN APPOINTMENT TO INSPECT, CALL ^mPLANT&MACHINERYlNC AiraONEERS'LlQUIMaS' APPRAISERS -REAIESWE BROKERS 8705 Katy Fwy, Suite 300-Houston, TX 77024 RON BRAMAN 800-282-8466 (USA and Canada) 713-691-4401 • Fax 713-672-7905 UNIVERSAL METALS & MACHINERY, INC. 9411 Wallisville Road Houston, TX 77013 JULIUS FEINSTEIN • BILL PHILIBERT 800-325-5286 (USA) or 713-675-2729 Fax 713-675-7819 • e-mail at umtl@io.com Circle 263 on Reader Service Card 97
