feed drive hydro stat noisy on jag 940 ??

[Monrad]

Machine is working at 1700rpm, feed drive hydro stat is noisy. Have pressure tested system, checked cylinder brake and 2 speed gearbox and all seems fine.
Has done so from brand new, not getting any worse but cant find whats causing it. Any ideas??? She's a 2009 with 375 hrs.

 

[trukfan]

Is the hydro attached directly to the motor, or is it shaft driven and coupled together? If it's coupled, it could be the couplers are loose or sized wrong, leaving side-to-side slop and making the racket. Is this some type of feed grinder, or mixer/grinder of some sort?

 

[JAGMAN]

This machine is a claas jaguar 940 forage harvester. Pump is driven via main drive belt to the cutting cylinder. The 2 speed gearbox the feeder hydro unit drives have givin problems in the past with premiture bearing wear. Check that all the pump mounting brackets are ok and not cracked due to this area being a week point also. good luck.

 

[maytag]

noise

Noise is a hydraulic system usually results from either cavitation or air entrainment of the pumping medium. Doubtful that you are experiencing cavitation in a (closed circuit)hydrostatic system and not be experiencing other symptoms.
Air entrainment is another story and can generate a lot of noise. First inspect your pumping medium(oil) after the machine is at operating temp-see if there is either foam on top or air bubbles in the fluid. If either are present then look for the source-loose fittings on suction line, pump shaft seal bad allowing air to be pulled in, etc.

Good luck,
Maytag

 

[JAGMAN]

I have been out to this machine since last post to see for myself what is going on with it. Have checked the oil for foaming but nothing there. Have pulled the main foward and reverse releif valves and checked for damage and all apears to be ok. Swapped the valves over also to see if fault would change but nothing. Releif valves are set to 420bar and unit is only working at about 200 to 220bar when engine is at max load. Have pulled cutting cylinder brake and checked for damage and found nothing also. Have watched brake pressure also to see if it is creeping on while working but nothing is happening. Have also checked accelerater housing for cracks as have had a few new machines crack these and start a high pitched squeal for accelerator but nothing found. Have spent about 2 days checking over this machine while its been working just cant quite pin point it yet. Any advice is welcome.