I own a 2007 schwing 32 xg. I bought this machine new. The other day while pumping a 500 yard slab, the pump just started pumping at full speed uncontrolable. I switched it into emergeny mode and adjusted the knob and whithin about 15 strokes it eventually slowed down. Now even in emergeny mode every 1/2 hour or so while pumping it will do it again, causing me to tinker again and eventually it will slow down. I was extremely dissatisfied with schwing customer support. The first time I called they had no one to talk to me, and I was told to call back after lunch. When I called back they couldn't give me an answer. It was like this had never happened to any other machine. They told me to run it on low idle. This is the first problem with the pump I have had. Does any one know the fix to this problem?

I had a 99 schwing 32m that had this same problem. i want to say it was a loose wire.

check for a bad wire or a bad coil on your volume control solonoid.If the coil is close to the same as on KCP,Alliance,Concord 12V coil should be about 5 to 6 Ohms resistance between the 2 U shaped terminals

Those pesky stroke limiters will do it every time.Besides calling swing service,John Thomas had the same problem some time back.

We have an 02, 39X schwing and we were experincing the same problem ... the Opp told us that it would speed up, he would turn the stroke limiter down as low as it would go! We found a bad O-Ring in the Soft switch ... this rectified the problem! Careful when taking apart as there is a spring and a piston inside! Hope this helps! 

Yeah! got the same prolblem on my 97 36M,  I think itsnot in the stroke limiter circut but in the soft switch circut, watch the strokes, do they really stall out between strokes and then speed up again?

Hi Brad,

My name is Phil Serre, I was with previously with Schwing for 18 and a half years.  I think I may know a little about your problem, I saw your posting and thought I could give my two cents for what it’s worth. 

If you have the "hartman controls" stroke limiter then you might be losing your input - Put a gauge (0-50 bar) on the "MY" port and see if the pressure dramatically changes when the problem occurs (Caution - If you hit and restart the E stop then you could damage the gauge – if you went to one of my classes, look in the manual you got or if you can get your hands on the training manual I put more precious detail in it). The valve could be sticking – if so, a frequency updated may solve the problem -- you may just have dirt in your system and need a new valve. If you can, disconnect the angle plug off the solenoid, remove the “Hex cap” nut, loosen the locking nut, use an allen wrench to adjust the output for strike control (0-50 bar, watch on the “MY” port // 0 bar max 50 bar min) use for a day or two and see if this solves the problem – it would prove a input hydraulic problem. 

NOTE: If you did the Bypass correctly then it shouldn’t be a electrical problem – including wiring – because once you turn the bypass key then all power is removed from the solenoid (0 bar input) should be max output, and then you have to use the allen to adjust strokes.

If it is the “German style” stroke limiter you have to turn the big quarter turn handle to bypass it, but now it should be at minimum strikes (0-50 bar ((possibly 0-35 bar) on the “MY” port. You now turn out the black adjustment knob out to increase strokes - same techniques as before regarding testing.

One other possibility – if you have A11 Rexroth hydraulic pumps you may have a sticky regulator – this can be determined by checking the pressure on the M1 ports on the bottom of the pumps – watch if both M1 ports move together and if they move smoothly – again check with the manual.

Obviously this is getting really long for a posting- If you want, you can give me a call and I can talk you thought it.

Take care

Phil                           651-257-3773    Cell 612-840-9211

Pserre@frontiernet.net  

Yeah-What Phil said-I'll second that.  Yall know he's the teacher so you had better pay close attention!  I'm sure he went thru that in school but my belly was full of all the "free" stuff I injested during the furthering of my education.  Good to hear from you Phil-John the pumper (world hdqtrs, Olathe Kansas)

An informed opinion is a thing of beauty. ;~)

Put a gauge on the output port markedMX1 if you have no pressure when the problem is there you most likely have a bad valve. Does not sound electrical. I work in the Schwing service dept and you can call my cell to discuss further. 612/845/6951