swift1894 Posted December 9, 2015 Report Share Posted December 9, 2015 When I fitted a Leece Neville alternator to my 4LW years ago, I was warned about possible wear on the front crankshaft bearing due to the pull of the belt on one side. Is there any basis for this? Link to comment Share on other sites More sharing options...
by'eck Posted December 9, 2015 Report Share Posted December 9, 2015 First thought is that it would be a greater worry on a modern flimsily built engine than a 4LW. Second is the side force would increase with the axial distance from crank front main bearing surface to pulley belt groove. I guess one alternator each side would balance side forces to some degree as well. Link to comment Share on other sites More sharing options...
Split Pin Posted December 9, 2015 Report Share Posted December 9, 2015 When I fitted a Leece Neville alternator to my 4LW years ago, I was warned about possible wear on the front crankshaft bearing due to the pull of the belt on one side. Is there any basis for this? Non whatsoever, there is a roller bearing fitted just behind the crankshaft pulley which will take far more load than you can apply by a pair of "V" Belts. Steve Link to comment Share on other sites More sharing options...
martyn 1 Posted December 9, 2015 Report Share Posted December 9, 2015 (edited) Non whatsoever, there is a roller bearing fitted just behind the crankshaft pulley which will take far more load than you can apply by a pair of "V" Belts. Steve Not necessarily true, many of the LW series of engines do not have the bearing you speak of. many just have a oil control scroll similar to the flywheel end. Having said the above either way your still not going to induce enough load with a properly tensioned alternator to cause an issue although you will be causing a little more load on the LW type with a scroll that the type with the bearing due to the extended lever between pulley and the first support bearing. Edited December 9, 2015 by martyn 1 Link to comment Share on other sites More sharing options...
Sir Nibble Posted December 9, 2015 Report Share Posted December 9, 2015 I don't know for sure one way or another but do remember that a big alternator will put far more tension on the belts than the normal service tension and Gardners usually drive generators from the timing chain. Link to comment Share on other sites More sharing options...
PeterG Posted December 9, 2015 Report Share Posted December 9, 2015 When I fitted a Leece Neville alternator to my 4LW years ago, I was warned about possible wear on the front crankshaft bearing due to the pull of the belt on one side. Is there any basis for this? Why the question, do you think this has caused a problem on your 4LW? Link to comment Share on other sites More sharing options...
swift1894 Posted December 9, 2015 Author Report Share Posted December 9, 2015 (edited) Not necessarily true, many of the LW series of engines do not have the bearing you speak of. many just have a oil control scroll similar to the flywheel end. Having said the above either way your still not going to induce enough load with a properly tensioned alternator to cause an issue although you will be causing a little more load on the LW type with a scroll that the type with the bearing due to the extended lever between pulley and the first support bearing. It's a marine 4LW. Don't know if that means it will have the roller bearing or the oil control scroll.Also the belt is a 7 multi-vee type which I imagine doesn't need as much tension as an ordinary single or twin vee belt setup. Why the question, do you think this has caused a problem on your 4LW?No. Just wondered. Edited December 10, 2015 by swift1894 Link to comment Share on other sites More sharing options...
Sir Nibble Posted December 10, 2015 Report Share Posted December 10, 2015 Also the belt is a 7 multi-vee type which I imagine doesn't need as much tension as an ordinary single or twin vee belt setup. The major tension on the belt is not from the adjuster, it's from the pull needed to turn the alternator and that is down to the required torque of course. Ideally spin an alternator as fast as you can in order to minimise torque and therefore side thrust. Link to comment Share on other sites More sharing options...
MtB Posted December 10, 2015 Report Share Posted December 10, 2015 (edited) I suspect the force applied to the front main bearing by the alternator belt is trivial compared to the force applied to it by the weight of the crankshaft plus the downward force of the front piston on the combustion stroke. Although the vector is in a different direction. (Spelling edit.) Edited December 10, 2015 by Mike the Boilerman Link to comment Share on other sites More sharing options...
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