Tài liệu Lesson 14- The Shaft System pdf

Lesson 14- The Shaft System

The shafting is a major component of the propulsion plant, whose functions can be

summed up as follows:

First, to convey the power developed by main engines to the propeller to make it

rotate; and then, to transfer to the hull the propeller reaction resulting from water to cause

a vessel to move.

A single-shaft system is composed of screw shaft, intermediate shaft, thrust shaft,

thrust bearing, intermediate bearing, compartment stuffing box and stern tube. For a twin￾shaft system, a shaft bracket to be arranged outside the hull because the two shafting

centrelines are located at both sides and the stern tubes are farther away from propellers.

In this case the stern shaft is to be cut into two pieces, one within the stern tube called

stern shaft and the other on the shaft bracket termed as screw shaft with the propeller

fitted at its end.

The first length of the shaft system is referred to as thrust shaft, whose construction

is different from the intermediate shaft. The thrust shaft possesses a thrust ring, matched

with a considerable amount of thrust bearings and fitted tightly on the bottom members in

a solid structure to withstand the axial push. As stated before, it is the thrust shaft and

thrust bearings that convey to the hull the propeller reaction to drive a vessel forward.

Between the thrust shaft and stern shaft is the intermediate shaft, which plays the part

of transferring M. E. power and whose number of lengths depends on the hull length and

the engine room arrangement. And the bearings to support the intermediate shaft is

defined as intermediate bearings.The screw shaft is to be fitted at stern, to extend out of

the

Fig. 14.1

1-main engine máy chính ; 2-thrust shaft trục lực đẩy ; 3-thrust bearing ổ đỡ lực đẩy (bệ

chõi) ; 4-intermediate shaft trục trung gian ; 5compartment stuffing box hộp làm kín

buồng máy; 6-intermediate bearing ổ đỡ trung gian ; 8-stern tube ống đuôi ; 9-stern

shaft trục chân vịt ; 10shaft bracket giá đỡ trục ; l 1-propeller chân vịt ; 12-oil tank két

dầu ; 13-adjusting equipment thiết bị điều chỉnh

hull and to be joined directly to the propeller. Normally, a bronze sleeve will be fitted on

the shaft in way of bearings to stop it from sea water corrosion.