In a typical electrohydraulic mechanism, one constant-speed electric motor drives two variable-stroke pumps through a coupling and reduction gear. Other installations include two motors, one for driving each pump. Each pump normally drives one wildcat. However, if you use a three-way plug cock-type valve, either pump may drive either of the two wildcats. The hydraulic motors drive the wildcat shafts with a multiple-spur gearing and a locking head. The locking head allows you to disconnect the wildcat shaft and permits free operation of the wildcat, as when dropping anchor.

Each windlass pump is controlled either from the weather deck or locally. The controls are handwheels on shafting that lead to the pump control. The hydraulic system requires your attention. Make sure the hydraulic system is always serviced with the specified type of clean oil.

Normally, you will maintain three types of anchor windlasses-the electric, electrohydraulic, and hand-driven windlasses. Hand-driven windlasses are used only on small ships where the anchor gear can be handled without excessive effort by operating personnel.

The major work on a hand windlass is to properly adjust the link, friction shoes, locking head, and brake and to keep them in satisfactory operating condition at all times. In an electrohydraulic windlass, your principal concern is the hydraulic system.

A windlass is used intermittently and for short periods of time. However, it must handle the required load under severe conditions. This means that you must maintain and adjust the machinery when it is not in use. This practice will prevent deterioration and ensure dependable use.

Windlass brakes must be kept in satisfactory condition if they are to function properly. Wear and compression of brake linings increases the clearance between the brake drum and band after a windlass has been in operation. Inspect brake linings and clearances frequently. Make adjustments according to the manufacturer's instructions.

You should follow the lubrication instructions furnished by the manufacturer. If a windlass has been idle for some time, lubricate it. This protects finished surfaces from corrosion and prevents seizure of moving parts.

The hydraulic transmissions of electrohydraulic windlasses and other auxiliaries are manufactured with close tolerances between moving and stationary parts. Keep dirt and other abrasive material out of the system. When the system is replenished or refilled, use only clean oil. Strain it as it is poured into the tank. If a hydraulic transmission is disassembled, clean it thoroughly before reassembly. Before installing piping or valves, clean their interiors to remove any scale, dirt, preservatives, or other foreign matter.

WINCHES

Winches are used to heave in on mooring lines, to hoist boats, as top lifts on jumbo booms of large auxiliary ships, and to handle cargo. Power for operating shipboard winches is usually furnished by electricity and, on some older ships, by steam. Sometimes delicate control and high acceleration without jerking are required, such as for handling aircraft. Electrohydraulic winches are usually installed for this purpose. Most auxiliary ships are equipped with either electrohydraulic or electric winches.

Cargo Winches

Some of the most common winches used for general cargo handling are the double-drum, double-gypsy, and the single-drum, single-gypsy units. Four-drum, two-gypsy machines are generally used for minesweeping..

Electrohydraulic Winches

Electrohydraulic winches (fig 10-39) are always drum type. The drive equipment is like most hydraulic systems. A constant-speed electric motor drives the A-end (variable-speed hydraulic pump), which is connected to the B-end (hydraulic motor) by suitable piping. The drum shaft is driven by the hydraulic motor through reduction gearing..

Normally, winches have one horizontally mounted drum and one or two gypsy heads. If only one gypsy is required, it is easily removed from or assembled on either end of the drum shaft. When a drum is to be used, it is connected to the shaft by a clutch.

Electric Winches

An electrically driven winch is shown in figure 10-40.  This winch is a single-drum, single-gypsy type. The electric motor drives the unit through a set of reduction gears. A clutch engages or disengages the drum from the drum shaft. Additional features include an electric brake and a speed control switch.

CAPSTANS

The terms capstan and winch should not be confused. A winch has a horizontal shaft and a capstan has a vertical shaft. The type of capstan installed aboard ship depends on the load requirements and type of power available. In general, a capstan consists of a single head mounted on a vertical shaft, reduction gearing, and a power source. The types, classified according to power source, are electric and steam. Electric capstans are usually of the reversible type. They develop the same speed and power in either direction. Capstans driven by ac motors run at either full, one-half, or one-third speed. Capstans driven by do motors usually have from three to five speeds in either direction of rotation.

Figure 10-39.-Electrohydraulic winch units.

Figure 10-40.-Electric winch.

Maintenance of Winches and Capstans

You will maintain the winch or capstan similarly. Where band brakes are used on the drums, inspect the friction linings regularly and replace them when necessary. Take steps to prevent oil or grease from accumulating on the brake drums. Check the operation of brake-actuating mechanisms, latches, and pawls periodically.

Inspect winch drums driven by friction clutches frequently for deterioration in the friction material. Check also to see if oil and grease are preventing proper operation. Lubricate the sliding parts of positive clutches properly. Check the locking device on the shifting gear to see if it will hold under load.