Hello everyone, I have a problem with my Bomag BW 212PD 40 roller - the vibration is weak on both high and low frequency. The flow from the main pump is only about 50 L/min, but according to the specs it should be around 97 L/min on high vibration. The pump is a variable displacement type, and I can see it's going to full stroke, but still not delivering full flow. There's no overheating and no unusual noises. Has anyone experienced a similar issue or can suggest what else could be wrong? Any advice would be appreciated!
I think it's internal wear - the pump is slipping badly. At 50 L/min vs. 97 L/min spec, that's a loss of roughly 50% volumetric efficiency. Why this happens : Worn clearances between pistons and barrel, or worn valve plate allow oil to bypass internally back to suction. No noise/overheating because the leakage is internal—oil recirculates rather than building pressure Diagnosis : Check case drain flow (if equipped) - excessive flow confirms internal leakage. Measure pressure under vibration load - if pressure is normal but flow is low, pump internals are definitely worn Other less likely possibilities : Charge pump failure: If the main pump isn't getting adequate charge pressure, it can't fill properly and starves. Suction restriction: Collapsed inlet hose or clogged strainer - but you'd typically hear cavitation At this flow loss, you need a pump rebuild or replacement. Variable displacement pumps don't "half-work" - this level of slippage means significant wear.
Thanks for detailed replay, charge pressure is good 24bar on both side, when I turn on vibration I have 130bar on pressure side, and on another side of pump pressure is 8bar that is bit strange? There will be flushing valve on hydraulic motor it is set on 13bar. Also when measuring servo pressure on pump it is 15bar. I think if there is internal leaking will have overheating to ?
8 bar on one side vs 130 bar on the other is your smoking gun! That's not normal pump behavior; you have a directional issue, not just internal wear. The low-pressure side (8 bar) suggests the pump is barely loading - either the vibration motor on that circuit has massive internal leakage, or there's a valve problem. 130 bar on the other side is reasonable for vibration under load Check : Vibration motor: The circuit showing 8 bar likely has a motor with blown seals - measure case drain flow from that motor (high flow = failed motor) Flushing valve set at 13 bar: If stuck open or leaking, it dumps pressure before the motor loads up Flow divider/priority valve: If your system splits flow to two motors, a failed divider explains unequal pressures Internal pump leakage causes: You're right that severe internal leakage usually creates heat. The lack of heat + low flow + pressure imbalance points more toward motor failure or valve bypass than pump wear. Focus on that low-pressure circuit's motor and flushing valve first!
Motor is like new insides already checked. Will open pump to check it think something is wrong with swash plate in pump. And also not logical for me if something that no strange noice at all if something is wrong with not enough charge flow or low pressure side not enough oil will have noice
Measured flow from pump and it is maximum 50l/min so problem is with pump
I'm going to let Nik handle this, and the rest he responds in. A lot of testing should be done before condemning a pump or motor but what do I know?
To resume flow from pump is 50l/min, it is going to full stroke, working pressure is 130bar so it is ok, I think something inside with swash plate in pump is wrong, in high and low frequency flow is almost same.
Is this edc controlled? The the electrical current been checked? Movement of the edc hydraulic control spool?
Yes have directional valve on pump, it is ok curent is 2.6A on both solenoids and that is fine.
Problem found, two piston in pump, about 2mm cylinder block piston hole become bigger.
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