• Thank you for visiting HeavyEquipmentForums.com! Our objective is to provide industry professionals a place to gather to exchange questions, answers and ideas. We welcome you to register using the "Register" icon at the top of the page. We'd appreciate any help you can offer in spreading the word of our new site. The more members that join, the bigger resource for all to enjoy. Thank you!

Komatsu PC300LC-7, Arm In function loads up Hydraulics

P

Pocho86

Member
Joined
May 6, 2014
Messages
23
Location
Kihei
Occupation
Heavy Equipment Mechanic Owner Operator
I have a Komatsu PC300LC-7 Serial 50161.

What I do know is when you stretch the arm all the way out it does have a very very slow drift. My problem is when you stretch the arm all the way out and full stroke the joy stick all the way back, it goes about 1/4 of the way and the hydraulics seem to load up like its fighting something, you can even hear it in the engine a little.

I did a little research, Im not very Komatsu familiar. I know I do not have the hose burst valve thats by the gland of the cylinder. On the base of the tube there is a block but that seems to be just a block for the two hoses to connect to. I do have a drift prevention device that's mounted on the control valve in mind. Ive looked at the schematics and its the only thing I could see that would possibly cause my issue.

If any one can chime in on some more knowledgeable experience. I would appreciate it
 
John C.

John C.

Senior Member
Joined
Jun 11, 2007
Messages
12,870
Location
Northwest
Occupation
Machinery & Equipment Appraiser
I haven't worked on a Dash 7 model 300 but if the main control valve is like the Dash 6 machines there is a regeneration valve that is supposed to dump some of the oil from the rod side of the cylinder back into the piston side of the cylinder. We had some problems with those valves on the PC200-6 series machines back in the day. As I recall the valve was in the main control block and access was gained from the side between the valve and the firewall to the engine compartment. You will need a book to be sure of that. Too many old and tired brain cells to remember much of that time.
 
P

Pocho86

Member
Joined
May 6, 2014
Messages
23
Location
Kihei
Occupation
Heavy Equipment Mechanic Owner Operator
I believe it was a gradually getting worse thing. Its my brothers machine. Ive been working on mainly cat and case equipment the last 12 years but just hardly any experience with komatsu let alone a problem like this. I also think its a faulty relief valve but i dont think it is cause theres no load on the hydraulics when bringing the arm in.
 
You must log in or register to reply here.
Top