50
left lifting cylinder right lifting cylinder
1. anti-dust ring
2. axes seal
3.steel cap
4. O-ring
5.bearing
6.cylinder
7.piston rod
8.adjusting bushing
9.O ring
10.spring
11. circlip
12.spring seat
13.piston
14.support ring
15.valve core
16.circlip
17.hole seal
18.check valve
19.circlip
20.valve
21.O ring
22.speed limit valve
23. O ring
24.pin
25.chain joinr
26.nut
27.chain
28.chain wheel
figure 2-56 lifting cylinder and chain
■Stop valve motion principle
There is a stop valve on bottom of cylinder(figure 2-57),if high pressure pipe burst suddenly,
this valve can prevent load lowering sharply. Liquid from lift cylinder flow through stop valve slide
valve, between two cavities ,there is difference of pressure produced by oil pores around slide
valve; when pressure difference is less than spring force, slide valve has no motion; if high
pressure pipe burst, there is a big pressure difference to push slide valve plug up oil pores around
itself, only allow a little oil to flow through the pore of end of slide valve to make fork lowering down
slowly.
