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Gordon Keir
Mar 10, 2009 - 9:20PM
"A" frame design - position
I am preparing to instal my new engine (4108) and need to build A" frames to allow me to lift the engine / gearbox a few inches for the alignment exercise.
The engine / gearbox will be lowered onto the mounts by the club crane, then it is up to me to get it aligned correctly.
My question is - where is the strongest place on each side of the engine hole for the base of each "A" to sit on, and is there a particular design which works best for Seadogs.
I have a chain hoist with a balance bar.
Any advice would be greatly appreciated, as I am a 'first time' engine swapper !!
SeaDog Name (if owner or crew) TARRY
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Philip Ellis
Mar 11, 2009 - 12:04AM
Re: "A" frame design - position
Hi Gordon,
After reading your post it is unclear to me that after lowering the new engine onto the mounts why you would wish to the raise it again by a few inches, or is it that the mounts don't have nuts that allow the brackets to be jacked up or down for final alignment?
If they do then these nuts can be set high and the engine lowered until alignment is achieved, then finally locked up.
But to answer your original question: The load is probably best positioned outboard on the side deck adjacent to the toe rail as this sits on the shelf that the deck is bolted to this is glassed to the hull above the rubbing strake.
The A frames should concentrate bulk of the force downwards rather than outward and avoid point loading, most other areas particularly the cockpit I suspect could cause some stress crazing, which is something to avoid.
I hope this is helpful.
Philip
SeaDog Name (if owner or crew) Glyfada, ex Natuna
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Graham Matthews
Mar 11, 2009 - 12:03PM
Re: "A" frame design - position
Morning Gordon,
I agree with the other comments posted, but may have some other suggestions depending on what you are trying to achieve. If the mounts are not currently in place and you are planning to offer up the engine to mark the position you are going to have to shift it right out of the way again afterwards to fit them anyway. Make sure the beds are sound and that you have strong fixings too. On Dougal we have lengths of 1" stainless bar inserted through the beds and threaded to take one of the studs on each mount. I know that TwoTails has a long length of angle iron firmly attached to each bearer.
Can't you use the club crane twice?
When we fitted the BetaMarine in Dougal we were lucky enough to be able to keep the crane while the mounts were fitted.
Graham
SeaDog Name (if owner or crew) Dougal
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Gordon Keir
Mar 11, 2009 - 8:38PM
Re: "A" frame design - position
Thanks Philip and Graham for your replies.
The new mounts are exactly the same as those in place under the 4107. I tracked down the manufacturer (R & D Marine) and they identified them as being 10 years old from the stampings - and as they are still available I have replaced them like for like thru ASAP Supplies.
The mounts are therefore in place and the beds are in good condition - they have a bar inserted (as per yours Graham), with a bolt sticking up to take one end of each mount, and a coach bolt at the other end which still bites OK into the wood.
The 4107 had the bolts at the bottom of the mount threads when I removed it - then a heavy washer and shimms in place to achieve the final alignment, so I had not thought of setting the nuts slighty high and lowering the engine down to align it.
Perhaps I only need to take the weight enough to be able to move the whole unit in the horizontal plane - or can this also be achieved in some way without the trouble of an "A" frame and block and tackle ??
Regards Gordon
SeaDog Name (if owner or crew) TARRY
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Eric Richardson
Mar 11, 2009 - 9:14PM
Re: "A" frame design - position
Hi Gordon
I do not see why you need to move the engine in a horizontal direction if it was ok before. The bottom nuts on the engine mountings can lift the engine with no problem and are intended to be used as a jack allowing you to lift and lower the engine as desired.
If you have need of a lifting frame the loads are best taken as Phillip says well outboard. I have done this with a few bits of hired scaffolding, Start by placing a piece of heavy timber along each side deck pushed as far out as possible. notch it out for the scaffold tubes to sit in and make two A frames about 4ft apart at the base then joined at the top by a short straight tube. It produces a solid lifting frame with very little effort.
Regards Eric
SeaDog Name (if owner or crew) Ex Taliesin
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Gordon Keir
Mar 11, 2009 - 10:28PM
Re: Re: "A" frame design - position
Eric.
If only - the marine gearbox man who checked why the rear seal let all the oil leak out - suspected a "rope around the prop" had at some time applied a considerable force to the engine and gearbox - new clutch plates, seals etc have now been installed.
On removal one of the front legs on the 4107 was bent, the Silentbloc couplings on each end of the short shaft were chewed up and the shaft itself was running out of true.
Couplings replaced 'like for like' and the shaft is now running true after including shimms on the flanges - so I do not have the benefit of a decent old alignement to use as my starting point.
Gordon
SeaDog Name (if owner or crew) TARRY
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Philip Ellis
Mar 12, 2009 - 12:30AM
Re: Re: Re: "A" frame design - position
Hi Gordon,
Having recently removed the engine, the tail shaft,the intermediate shaft plus couplings and refitted new R&D mounts and addressed the alignment problem I can sympathise with your situation.
If it is any help the co-ordinates of the holes in the feet on my engine /gearbox assemly (4108/Velvet drive) is as follows: Plan view,18inches x 28inches. In elevation the front bearing surface is 1.5inches below centre line with the gearbox bearing surface 2.675inches above the centreline.
I made a template to simulate the engine whilst relocating my new mounts The downslope of the centreline is 12.5deg.
The template was aligned to the shaft centreline using a laser light housed within the cutlass bearing, rotating the laser to check that the spot on the fwd b/head had little or no ecentricity confirmed its accuracy.
However if you have replaced the engine mounts like for like and they have taken up the same footprint and the front bracket on the engine has been straightened and matches its oposite then as Eric suggests why not drop the engine onto the mounts with lower nut elevated slightly above the old height that the packing gave and the studs in the centre of the slotted holes in the feet, then assuming level waterline try for 12.5deg down angle (Long wedge and spirit level)on clyinder head .
One thing I would suggest is that you fit a very heavy duty washer on top of the lower nut this will give a much better bearing surface for adjustment and susequent wear.
Can I assume that the washers fitted to the shaft couplings are a temporary fit to pull the gearbox end to run true whilst you check for close coupling? as the silent bloc coupling relies upon the step in the end of the bush through which the bolt passes to locate in the recess in the metal yoke.
When the engine is in and you slide the shaft forward it mates easily with the gearbox half on each half revolution then its probably as good as it gets.
It is dificult to nudge the engine sideways because the flex in the mounts tend to defeat you, but can be done in the small ammount that we are talking about, the front one are the most dificult to access.The two flexible shaft coupling will absorb any small misalignment, which will occur as the engine mount flex and age.
Again I hope some of this may be of help.
Regards
Philip
SeaDog Name (if owner or crew) Glyfada, ex Natuna
Gordon Keir
Mar 12, 2009 - 6:37PM
Re: Re: Re: Re: "A" frame design - position
Thanks Eric and Philip - I am glad now that I asked the question.
The engine / gearbox will be ready for fitting in April, so I can get on with making a simple "A" frame in preparation.
I also have a template taken from the 4107 so I will double check it against your measurements for the final placement of the mounts. I will then be ready to make the vertical adjustment using the bolts, and the horizontal adjustment with the "A" frame taking enough weight to allow the whole unit to be coerced sideways.
Gordon
SeaDog Name (if owner or crew) TARRY
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