ex 270 hydro problem

This topic contains 7 replies and was last updated by dan-woodbury 8 years 10 months ago
December 14th, 2012 4:03pm
Hello, new to this forum so here is my question. I ave an ex 270 hitachi 1994 i believe. i am having problems with it swinging slow. Sometime it will work fine, other times you will start to swing and it will be slow {i mean real slow} and if you keep it swinging it will just kick in and speed up. Just like a valve is sticking. Any advise how to diagnose this would be wonderfull.
December 15th, 2012 5:02pm
Hi Dan,

I'm experienced with Cat equipment, and not Hitachi, but maybe I can provide some diagnostic ideas. On Cat excavators, there is a wet disc pack inside of the swing drive which acts as a swing brake. Usually the swing brake will be spring applied, hydraulic release. This means that if your swing brake piston starts to leak, the hydraulic pressure to release the swing brake will be insufficient, and the spring will apply the swing brake. Usually, there is a swing brake solenoid that is provided electrical power through an implement pressure switch. When hydraulics are activated, hydraulic pressure increases, electrically closes the implement pressure switch, and the implement pressure switch feeds power to the swing brake release solenoid. When the swing brake solenoid is electrically energized, hydraulic flow is provided to the swing brake to release it.

I recommend that you find your swing brake release solenoid and verify that it being provided electrical power when problem occurs. If there is no electrical power at the swing brake release solenoid, check your implement pressure switch, if equipped. There may be an ECM that provides power to the implement pressure switch. If electrical power at the swing brake solenoid is ok, plumb a pressure gauge into the swing drive brake release line, and monitor your brake release pressure when problem occurs. If release pressure drops, when problem occurs, you might have a leaking swing drive brake piston.

Are any of your other hydraulic functions slow or erratic? Do you hear any mechanical noises coming from your swing drive pinion and ring gear area between the upper structure and the undercarriage? Do you see any slop in the swing drive pivot area when swinging? If this machine has electronics, you might be able to monitor the swing brake release solenoid and implement pressure switch status from a computer or from the cab monitor.

As I said earlier, I am not familiar with the details of Hitachi equipment so you may have to dig deeper into the details of how your machine swing brake control is set up.
December 22nd, 2012 1:38am
thank for the tips. There is other functions that are slow too tracking, dipper stick and swing . as your digging it will come and go. the pump does sound like its cavating when its acting up. like i said its like u turn a switch on and off it seems like when its cold its worse and it gets better the warmer it is. any help please.
December 30th, 2012 4:55pm
hydraulic systems has two different circuits open and closed diagrams has own adantage.one of the chracateristic of closed circuit hydraulic systems is the hydraulic tank kep under pressure for pilot pump to suck well.if the tank pressure is too low or olil level is low then the cavitations occur and thus your main pump isnt adjusted to supply enough pressure and oil to the system.pilot pump missions to supply the main pump to be adjusted itself considering the load and second lubricate the main pump.
December 30th, 2012 5:07pm
excellent explanation.
February 3rd, 2013 11:41pm
Electron Exciter has it covered good for you.When you swing the machine did you ever try to use another function say on the other control stick? It may be that the pump is not stroking out and the flow will be reduced thus giving you slow movement.You may have a regulator problem affecting the pump.If you use another function and it speeds up then you have a load sense problem or as I said before a pump regulator malfunction. I think a day with a service manual an a pressure gauge is in order and maybe a flow meter.Good luck.
February 8th, 2013 3:17am
I think Will hit the nail on the head pump or pump regulator sticking, most excavtors have 2 pumps 2 regs and the control valve gets fed sort of in 2, so if the tracking problem is the slow track spool is on the same side as the swing spool or any of your other slow functions BINGO that is your bad pump or reg. if manuals,flow meters are hard to get and you dont mind a small adventure swap your pump output lines and your slow problimatic hydraulic functions will change to the other side of control valve. not sure if Hitachi uses negacon control or not, if they do a negacon relief valve failing intermittently could cause these symptoms but doubt it, good luck.
May 26th, 2013 11:29am
I’ve never tried my G1X with an EX270 but the first thought that comes to mind is that the interval between the shots is too short to allow the flash to recharge before the camera fires the next four shots.

Possible solutions might include

open the aperture wider. This will require less flash power and perhaps give you more flashes per recharge. OTOH it may not be possible if you were already at maximum aperture and/or it may not suit your DOF requirements

move the flash closer (on a cable – I don’t think the G1X or EX270 support wireless). This may not be feasible either.

set longer timer intervals so the flash can recharge. This of course may not suit a group of people…….

Hope this helps explain possible causes of your dilemma, even if it doesn’t provide an easy solution.


Rachel !!!

Reply to: ex 270 hydro problem