510 APPLIED MECHANICS 
used expansively, and therefore more economically. Hence the advantag 
of fly-wheel pumps. "oe 
Many contrivances, other than the fly-wheel, have been tried to e 
the direct driven steam pump to use the steam expansively. One, 4 
has been used with great success on large pumping engines, will ne 
described. This is the compensating cylinders of the Worthington pur 
engine. Fig. 818 shows a triple-expansion pumping engine having ! 
steam cylinders and a water cylinder in line, the three steam pistons and 
Lehn 
the water piston moving together. In the particular engine considered, 
the high pressure piston and the water piston are at opposite ends of a 
piston-rod connected to a cross-head A. The intermediate and low pres- 
sure pistons are connected by a central piston-rod B. The low pre 
piston is connected directly to the cross-head A by two other piston- 
which pass through the front end of the low pressure cylinder, but 
rods pass outside the intermediate and high pressure cylinders. CC : 
the compensating cylinders, which are mounted on trunnions to pe 
them to oscillate. The compensating cylinders are provided with rams, 
Fig. 818. — 
WW 
ULddddddddddddd ddd 
WO 
SK RQ 
SS WMG SS 
SSK 
S 
WN 
SS 
S 
AXXO 
S 
SN 
WC 
\ 
Lay Ae 
Dale pccccccecq:cccccccecceedlecccclecta 
\ 
Vip 
N Upp yy 
S@e N N_ 
) 
Siwy, 
SSN 
i 
77 
«f#@ 
Fira. 819. - 
on the outer ends of which are formed gudgeons, which work in bearin 03 
on the cross-head A. . 
