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
Digital Wave Publishing