PDA

View Full Version : shaft alignment


mariner2k
07-10-2002, 07:26 PM
Does anyone have any experience with a misaligned shaft? I noticed some side to side movement in my stuffing box. How much of a problem can this be? And please, don't tell me to see a doctor.
mariner
On Vacation
07-10-2002, 07:57 PM
Your question is very hard to answer here. There are many reasons for this and many results of this problem. The major problem would be the bearings in your struts wearing out. Bad motor mounts will do this as bad output flanges and facings of the flanges. Side motion is usually alignments if all other parts are new or in good condition. Do you have a vibration in the boat?

If you do then it can cause screws backing off and fitting to work lose. Give us a little more info.
mariner2k
07-10-2002, 08:32 PM
Everything seems to be in good shape.mounts bearings etc. The boat doesn't seem to vibrate, or at least I can't notice it. I notice it at very low speeds visually but not at higher speeds. I suppose i am wondering if this needs immediate attention or can it wait until next winter?
mariner
On Vacation
07-10-2002, 08:40 PM
It is very common for a misalignment to vibrate at slow or idle speed and at top end not. SOmetimes the engine can be so out of alignment that it in such a bind that it will not shake at top end.
dale o
07-11-2002, 12:22 AM
It seems to me you're describing side to side movement at the packing. Misalignment would be measured by breaking apart the coupling and measuring the side-to-side and face -to-face alignment for the coupling halves. In a typical stern tube shaft arrangement, with a rubber bearing at the prop end, you don't really have anything but the packing in the packing gland to hold the precise shaft alignment.
You may be looking at loose or worn packing, or the shaft may be worn at the packing gland area, allowing the movement you see. If you don't have excesssive leakage or noticable vibration, you may not have a big problem. How old is the installation? At some point you may want to repack the shaft and inspect the condition of the shaft. After that, you can check the precise alignment of your engine to the drive shaft. A book on basic pump installation and repair or inboard motor installation can give you more information.
mariner2k
07-11-2002, 05:21 AM
The packing is new and the bearing is just a couple years old. The shaft sits tight in the packing with just the ocassional drip. the whole stuffing box moves a bit.
thanks, mariner