We are having a serious problem regarding Crank breaking in one particular forklift, where there is a fleet of about 10 forklifts of the same model, there is one particular forklift where there is repeated crank breakage after every 1000 hrs or so of operation. Engine is Hercules 2.7l and all the forklifts are operated on LPG fuel. Could someone help me out as this is a matter of grave concern.
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check the bushing on the flywheel where the torq conv. meets the fly wheel ive seen these on diferent trucks
check the bushing on the flywheel where the torq conv. meets the fly wheel ive seen these on diferent trucks
unfortunately this is one weakness this particular engine has, you may notice the engine has only three mains instead of five. I would get the rotating assembly dynamically balanced and have a look at the torque converter as mentioned.
Thanks Tom. The breakage in the crank shaft is occuring on the main journal at the rear {from fly-wheel side}. In this forklift vibration generally occurs if idle rpm falls below 775/750 rpm. We set the idle rpm to 800+/- 250 and in this area vibration does not occur.
This engine doesn't have an internal balancer or use a dampner on the front like most. Some of these engines simply vibrate a lot and there is little or nothing that can be done about it. Unless you want to spend a the money to get the engine balanced in a professional shop that is equipped for such work. If your engine is one those that vibrates a lot the excessive vibration can contribute to crank breakage. To help the vibration at idle you may want to increase the idle speed a little to smooth it out. However, this will not do anything for the vibration in the next vibration cycle at a higher speed. As for the converter, it is cheaper to just replace it. Is your crank breaking on the front or the rear? We have had some of these pass thru our shop, however, we have not had any with broken cranks as a result of the vibration. Most of the time the vibration is just an aggravation to the operator.
Thanks Tom for your reply. Could you please let me have some more information on the "Vibration Damper". The engine in question is Hercules 2.7l fitted on G20S-3 Daewoo Forklift. Where would this Damper be located??. Regarding Balance of the Torque converter, how do I get that checked??
The location of the breakage can be a strong clue as to the problem. If the break is towards the front of the crankshaft the vibration dampner is a strong suspect. If it is a rubber mounted dampner the rubber can allow the outer ring to slip and defeat the purpose of the dampner. Crankshaft breakage towards the front of the shaft is usually the result. If the breakage is towards the rear, I would inspect the flywheel and/or clutch for being out of balance or the torque convertor, if it has one. If the engine powers front driven accessories they could also be a factor.
Hope this helps...Good Luck.
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