Tadano TT-800XXL1, Service Manual

Page: 90 / 267

E-1. E-1.
Elevating System
1
WE02-0230E
Elevating System
1 . Description of the units
1 . 1 Elevating cylinder
1 . The elavating cylinder serve to elevate the boom.
2. A pressure sensor is installed to input the value to
the AML for calculating load moment.
1 .2 Counterbalance valve
1 . This valve serves to prevent the cylinder piston
rod from pushed in by the load during boom
lowering to maintain the lowering speed at a level
determined by the oil entry flow rate to the
cylinder.
2. It also prevent the retraction of the piston rod
when the piping between it and the manual control
valve is broken.
1 .3 Select valve (dolly)
1 . To travel with a dolly hitched to the rear of the
carrier, it is required that the hydraulic circuits for
the boom elevating cylinder and swing motor be
free so that the boom can follow the movements
of the dolly while travellring.