Summary

The excavator is a main consrtuctional machine，which is now widely used

in   various   construction   sites.The   core   technique   of   excavator   is   hydrau1ic
technique.   Becauseofthe   bad   working   condition   and   conmplicated   working
movements   of   the   excavatot ， it   has   high   requitements   for   its   hydraulic
system.Since the excavator’s hydraulic system is the most complicated one in
all constructional machines ,the analysis and research of its hydrau1ic system
make very important sens.

On the basis of comprehensive co11ection of re1ated information about the

excavator’s   hydraulic   system   at   home   and   abroad ， the   main     working
conditions   of   the   excavator   are   studied   and   the   design   requitments   of   its
hydraulic   system   are   systematically   summarized.   According   to   the   design
pressure compensated  hydraulic system  is  creatively  designed  using  general
multiple until value equipped  with special contol valve  and  electronic contor
systems,which   has   useful   reference   value   for   the   future   research   and
development of the excavator’s hydraulic system in our country.
The   name   of   this   graduated   task   is  “SWE70H”   medium  type   hydraulic
excavator”.This   task   is    requested   by   company.   My   task   is   to   analyze   and
design the hydraulic system of the medium type hydraulic excavator. This task
choose the domestic excavator whose quality and character is most similar to
our request as the basic type, further study the overseas advanced type. Then I
designed projects of hydraulic system of our excavator,collectivity assemblage
drawing and interrelated parts drawing, accessory drawing. All the blueprints
drawn by the soft of AutoCAD. The strongpoint of this hydraulic excavator is
used servo forerunner control system. It has beautiful sculpt. Beijing provided
with the fuction of excavating, grappling, drilling, pushing, cleaning channel and
crashing   etc.   360°swwing   plat   roof,good   quality,   controlling   comfortable,   be
widely used in construction,supply and city planning.