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Cat 336 delayed response

tbone1471

Well-Known Member
Joined
Oct 31, 2010
Messages
207
Location
southeast pa
Cat 335fl
Rkb10639

When using the controls it seems like the hydraulics have a delayed response. It is the same when letting go of the joystick. The machine takes about 1 or 2 seconds to stop functioning.

it makes it very difficult for delicate work.
For example if I pull the control back to raise the boom it will linger for a second then start to raise. If I let off the boom may go up a few more inches. Any suggestions as to what may be the cause?
 

aongheas.macask

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Joined
Nov 12, 2008
Messages
105
Location
Scotland
Occupation
ex service manager
Cat 335fl
Rkb10639

When using the controls it seems like the hydraulics have a delayed response. It is the same when letting go of the joystick. The machine takes about 1 or 2 seconds to stop functioning.

it makes it very difficult for delicate work.
For example if I pull the control back to raise the boom it will linger for a second then start to raise. If I let off the boom may go up a few more inches. Any suggestions as to what may be the cause?
Air in your Servo system most likely
 

uffex

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Jan 23, 2012
Messages
4,464
Location
Lincoln UK
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Admin
Good day
That suggests the RCV (Control lever) is taking its time to drain> possible cause blocked case drain filter or to heavy grade of hydraulic fluid.
Kind regards
Uffex
 

tbone1471

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Joined
Oct 31, 2010
Messages
207
Location
southeast pa
I thought these controls were electric over hydraulic? I'm would assume there is still a pilot system but it is controlled by solenoids not the joysticks directly?
 

uffex

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Good day
I have not checked if you have a hydraulic schematic, that will reveal which you have. You are correct if it has electric over hydraulic the same situation would apply
KR
Uffex
 

uffex

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Good day
In the spec. I have fails to mention other than "Electronic control of the main block" maybe Nige has the information.
KR
Uffex
 

tbone1471

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Joined
Oct 31, 2010
Messages
207
Location
southeast pa
I think that machine does have a pattern changer. But the controls are electric over hydraulic. So no pilot lines in the cab.
 

tbone1471

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Joined
Oct 31, 2010
Messages
207
Location
southeast pa
I will have to get a look at the machine later this week. But I thought all the controls on the f series were electric pilot?
 

Vetech63

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Joined
Aug 10, 2016
Messages
6,362
Location
Oklahoma
I'm not sure on your machine but in some there is an inline filter on the return circuit of the pilot system. I would start there if you have it. Slow nuetraling response is usually a restricted return circuit in the pilot hydraulics
 

Nige

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Joined
Jun 22, 2011
Messages
28,979
Location
G..G..G..Granville.........!! Fetch your cloth.
Attached procedure for changing the implement pilot filter. Element P/N is 5I-8670.

The pilot system on this machine has an accumulator. Has anyone checked that it is functioning correctly.? It is quite simple to do, see Steps 1 thru 5 of the "Preliminary test Procedure on Pages 2/3.
 

Attachments

  • Pilot Filter.pdf
    890.5 KB · Views: 8
  • Accumulator.pdf
    1,022.6 KB · Views: 6

John C.

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Joined
Jun 11, 2007
Messages
12,865
Location
Northwest
Occupation
Machinery & Equipment Appraiser
Unless this is something different, the accumulator is used to lower the boom or stick if the engine is dead. It shouldn't have anything to do with the delay. It used to be one of my inspection checks but I found so many flat ones that I quit checking them.
 

tbone1471

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Joined
Oct 31, 2010
Messages
207
Location
southeast pa
recently made it back out to this machine for some other repairs but need to circle back to this... If it still runs it can't be that bad...

Tried the accumulator test while on site. Didn't have any gauges but the boom does not come down with the machine off. Tried it on another one at the shop and that machine also did not work.

While working on this I was in the service menu and noticed the pilot pressure surging. 300-600 psi. kind of rhythmically. It is visually noticeable in the aux lines at the boom to stick. The lines pulsate slowly.

Is there a valve or something in the pilot system I can check with relative ease next time I am at the machine? Often I am very limited on tools while on site. We try to get the machines to the shop once per year for major work but it seems the last few months it is just keep everything moving with no down time between jobs.
 
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