DESCRIPTION GENERAL
Gearboxes of the new GTD-Series have been developed for wet dredging applications such as cutter gearboxes installed on an open or encased cutter ladder with different working angles. These gearboxes with helical and spur gearing are in two- or three-stage design, with one or two input(s)- and one output shaft.

Options:

• Different design / offset on request
• Turning drive
• Highly flexible / air clutch coupling
• Mechanical overload protection
• Electronic overload protection for gearbox with air high elastic clutch
• Supervision instruments acc. classification rules

HOUSING
The housing which consists of a bottom, middle rsp.a top section is in welding construction. The torsionally-stiff design warrants a safe torque and transmission to the ship’s foundation.

GEAR WHEELS
Input and intermediate stages have single helical gear teeth, output shaft in spur gearing. All gears in case-hardened and ground design.

SHAFTS
The input shafts have been designed with cylindrical shaft journals with fitting key for accommodation of the highly flexible / air clutch coupling combination.
The output shaft has a forged on flange connection. In case of integrated thrust bearing the thrust ring is forged on as well. The surfaces of external flanges, ends of shafts and flange attachment face are preserved with an anti-rust coating.

BEARINGS
The gearbox shafts are borne in roller bearings, rsp. plain bearings.
The thrust bearing is of Mitchel design with round thrust pads for ahead and astern.

GEARBOX OPERATION
Gearboxes supplied by GTD arenot filled with oil.The oil supply system of the gearbox is standing separately.

GEARBOX TYPE : … (standard design)
Drive effects by an electric motor via a highly flexible / air clutch coupling combination.
Air feed effects by hollow bore in the input shaft.

GEARBOX TYPE : A … (with integrated thrust bearing)
The radial and axial forces, coming from the cutter head, are absorbed by the thrust bearing
on the output shaft.

GEARBOX TYPE : N … (gearbox in three stage design)
Type S : On request gearbox can be also supplied in two-stage design
(max ratio 33:1)

TURNING DRIVE
Electrically driven frequency controlled multistage turning gearbox for changing of gears as well as for assembling respectively disassembling the cutting tools of the cutter head.

LUBRICATION AND COOLING
All of the components required for the lubrication and cooling are mounted next to the gearbox and permanently interconnected by pipe work. The oil is supplied by 2 electrically built on lube oil pumps. Gears and bearings are lubricated by forced oil circulation. The gearbox casing serves as an oil reservoir. The min. / height of oil levelin the gearbox are controlled by a level control device.
The oil is cooled by a water-oil cooler for fresh or sea water.

MONITORING
Visual and electrical control devices for pressure, temperature and oil level are installed in lubrication circuit. All electrical devices are cabled into a terminal box.
Furthermore information:
- signal list / alarm points: acc. hydraulic scheme resp. table of contents
- gear switching acc. pneumatic scheme

PAINTING AND PRESERVATION
The gear unit is painted internal and externally with a finished paint coat acc. GTD-Standard (by request externally acc. customer specification).
The internal preservation of the unit is done using with GTD-test run oil, which provides adequate corrosion protection for a period of 12 months, if the equipment is stored in a dry room.