No_2_April_and_May__1939 — Page 33

Hong Kong Builder

39

-Concrete ready

for depositing

Layer of Concrete deposited during upward blow of hammer

Rise of Tube per upward blow

Fall of Tube per downward blow

Layer of compressed concrete rammed 80 times per minute

Fig. 4

between the concrete and the inner walls of the tube. Thus the tube moves up whilst the concrete remains stationary.

The effect of the light cushioned downward blow is shown in Fig. 5. The friction between the concrete and the tube now helps to make the concrete move downwards, the tube and concrete acting virtually as a solid ram exerting a considerable tamping pressure over the whole section of the pile. During this operation the layer of concrete is compacted and rammed outwards to fill the

Fig. 5

space left by the tube; a corrugated surface is also formed on the pile, increasing the friction between the pile and the surrounding ground.

This cycle of upward and downward blows is repeated 80 times per minute, a pile of dense concrete being formed at the rate of up to 4 ft. per minute.

Fig. 3 shows the completed 17 in. lia. Vibro pile, which may be finished at any desired level below the ground surface, according to the amount of concrete filled into the tube.

WE MANUFACTURE

STEEL

WINDOWS

& DOORS

IN

LIGHT, MEDIUM AND HEAVY SECTIONS

WE SUPPLY STANDARD SIZES

AND SHAPES DIRECT FROM STOCK

OR MADE TO ORDER FROM

YOUR SPECIFICATIONS

NEW

ALL METAL WINDOWS

FOR THE

CENTRAL MARKET

HONG KONG

WERE MANUFACTURED AND SUPPLIED

BY US

HONG KONG METAL WINDOW MFG., CO.

6 FUK WING ST..

TELEPHONE 58644.

KOWLOON