Deck Cranes

The crane to be rigorously function tested with 125% of rated hook load, through a full cycle of hoisting, slewing and topping operation. At the same time, all limit switches and pressure relief valves are adjusted to the desired position and settings.

Testing& Inspection

For interior of pedestal used as hydraulic oil tank, one coat of zinc rich epoxy primer is applied after abrasive blast clean of surfaces to SA 2.5.

For pedestal interior, only two coats of primer are applied after the abrasive blast clean of all surfaces to SA 2.5.

For exterior finishes, one coat of zinc rich epoxy primer (50MIC) with one intermediate coat of mastic mid epoxy (75 MIC) are applied before final coating by gloss finish paint (50 MIC).

Complete fabrications are sand blasted to Swedish std SA 2.5 prior to priming with zinc chromate.

Surface Treatment & Finishing

All welding is performed by certified welders to the correct welding procedure as per AWS Dl .1 STD including edge preparation for 6mm thick and above steel plates; pre-heat to 50 degree F; wire brush clean In between passes; and ensure 80% joint efficiency continuous weld etc.

The crane is a welded structure of ship plate steel, designed to withstand all operational stresses whilst protecting the internal machinery from humidity, sea environment influences and corrosion.

Fabrication & Welding

No limit switches are required for these cranes for continuous slewing or 360 degree slewing. In case of slewing sector less than 360 degree, two limit switches are installed at the extremes of slewing.

The topping cylinder is designed with cushioning effect for safe buffering in the extreme positions during lifting up and down operations.

The crane is installed with an automatic hook stop in the top position, to limit the maximum hook travel during hoisting.

Each hydraulic system is provided with relief valves for limiting hydraulic pressure to pre set valves corresponding to the crane operating capacity. Limit Switches (Option)

Load Limiting System

Two motions may be operated at the same time with full capacity but at a reduced speed.

The crane is controlled from an open platform above the slewing ring. Entrance to the platform is by ladder. All crane movements are smooth and fast, with stepless speed control throughout and protection against overloading by various relief valves.

Crane Control

Remote stop/start push button type can be supplied and mounted onto the crane pedestal upon request.

Star-delta or DOL starter is provided for power pack starting. It is supplied as a loose item for site mounting and is equipped with all the necessary start/stop buttons and indicating lights, etc on the front door.

The electric motor-pump unit can be explosion- proof type for use in the hazardous area upon request. Motor is equipped with anti- condensation heater.

The Plimsoll crane is constructed with a built-in power pack. The support column of the crane is utilised as a tank for the hydraulic oil. The hydraulic system has a full flow return filter with changeable filter element. The tank is provided with an oil level/temperature indicator, filler breather and drain cock.

Electro-Hydraulic Power Pack

The wire rope for the hoist winch is of the non rotating type and galvanised. It is 6 x 37 IWRC type with minimum breaking strength of 5 times the maximum hoisting capacity of the winch.

Rope

Sheave diameters are selected to suit the hoisting rope and are mounted on the boom outboard end, so as to properly guide the rope at all boom angles. Sheaves are provided with heavy duty roller bearings with external grease nipple lubrication.

The boom Is fabricated from 6mm thick ship plate ST37-2 or equivalent material, continuously welded in a rectangular box section.

Crane Boom

The support column is fabricated of min l2mm thick ship plate or equivalent material, rolled to the diameter to suit the slewing gear inner race dimension. A mounting plate of min. 2Omm thick is welded on top of column for bolting the inner race of the slew ring. The bottom of the column is to be welded onto the deck structure with webs.

Support Column

The slewing ring is a 4 point contact bearing type for optimum transfer of thrust and moment loads. It consists of an outer race bolted onto the rotating base plate, and a inner race, which includes internal gear teeth, bolted to the stationary support column.

The slewing drive unit, consists of a pinion gear mounted on the output shaft of a planetary type reduction gear, coupled with a spring set fail-safe brake, driven by a hydraulic motor. The complete drive unit is bolted onto the base plate and drives the inner race of slewing ring.

The crane slew is at the joint position of base plate and base column, activated by the slewing ring and slewing drive. It is fabricated from 2Omm thick ship plate or equivalent material.

Slewing

The cylinder is equipped with integral counter balance valve at the porting to prevent sudden retraction of the cylinder rod in case of hose burst.

The heavy duty marine type hydraulic cylinders have spherical bronze bearings on the clevis ends, mounted onto the boom and base plate using stainless steel pins.

The boom is topped by a hydraulic cylinder with sufficient stroke to achieve boom positions from horizontal to 80 degrees up, with the max hoisting capacity, at horizontal maximum outreach.

Topping

Complete with the skid frame, the hoist winch is mounted onto the top of the boom and close to the centre of rotation to ensure a low fleeting angle for even spooling.

Hoisting on the crane is done by a Plimsoll Hoist Winch, with the wire rope coiled on the drum to give sufficient hoisting height. The hoisting winch is provided with a hydraulic motor and fail-safe brake to prevent free-fall in case of power failure. The hoist winch is powered by the built-in power pack to give the maximum hoist capacity and hoisting speed at the top layer.

Hoisting

The steel quality is selected in accordance with classification societies recommendation to obtain necessary ductility and to withstand the lower temperature working environment.

A dynamic load factor of 1.25 times shall be applied to hook loads, for calculation of stresses. Such stresses shall not exceed 30% of yield stress of the material.

Plimsoll Deck Cranes are designed according to BS 2573 STD and also comply to the "Code For Lifting Appliances in a Marine Environment" of Lloyd's Register of Shipping.

Design Criteria

Plimsoll Deck Cranes consist of a steel fabricated boom with guide sheaves for the hoist cable at the outboard end. The boom is pivoted vertically on a base plate, and the topping motion of the boom is achieved by a hydraulic cylinder connected from the baseplate to the boom. The plate is rotated on a slewing ring, which is driven by a pinion mounted on the ring slew drive. The inner race of the slewing ring is mounted on the support column which is to be welded to the deck or platform provided.

TECHNICAL DESCRIPTION

In the standard version, our product range is generally in accordance with marine and industrial classification society regulations. Other sizes, can be provided to suit special requirements upon request.

The use of the most advanced Computer integrated Manufacturing and Computer Aided Design systems ensure the technical excellence of each individual crane designed, and enable us to meet our customers demand for a high quality product and maximum reliability on our cranes.

Plimsoll Fleetwinch manufacture a range of general purpose and deck cranes for marine, offshore and industrial applications.