6/1 and generator setup

[Guy_Incognito]

I'm slowly working my way towards getting a jkson 6/1 and a 5kW ST head for it. It'll be used in an off-grid setup to top up batteries once a week or so, with solar making up the most of the charging capacity. Charge time from flat of the battery storage should be about 8 to 10 hours of full load (3kW) on the 6/1, but I don't expect it to be completely flat all the time... just half the year in monsoon season  . I'm using new nickel-iron cells as - while inefficient - they're immune to discharge damage. I expect the system will be used and abused lots.

Anyway, going through the math involved it seems I need a 250mm diameter pulley on the generator to get 1500RPM and 50Hz at aroundabout 620-650rpm. I'm not completely sure of the flywheel size of the jkson engines - 23.5" ?

So, rough gameplan is :

- Source a 250mm, 8 groove poly-v pulley with a bush to suit the 38mm shaft

- Find a suitably-sized belt and bung the 6/1 and genny together on a solid frame

- Possibly get a small tensioner on the frame as opposed to stuffing around with a slide of some sort for the genny, as I'm sure to screw that up. - the pulley mob also stock some nice stepped tensioners that also serve as belt trackers.

- Mount frame with fairly solid rubber mounts bolted to a concrete pad. (Fairly solid as in rated at 500kg each rubber mount. It won't be all that flexy. Hopefully)

- Run cooling pipes to a fairly thin tall rectangular cooling tank and let it thermosyphon away. Dimensions guessed at 100cm long by 150cm high x 10cm wide or so - just want plenty of surface area for convective cooling, right? Anyone good with the calcs for this? Ambient is about 20 - 30 degrees C year round. There'll be a heat exchanger in there somewhere to boost my solar hot water system, as when it's cloudy I'll be needing to run the genny to charge the system up anyway.

Anyone see any showstoppers in this?

[mobile_bob]

where on earth did you get that name?

or rather what possesed you to use it?

just wondered

bob g

[Procrustes]

I don't see any showstoppers.

About the pad though, the Lister manual and the consensus here dictate that you should eschew any barrier between your engine and the sacrosanct concrete block.  It is nice to have the engine balanced also.  Said block should be a 6' cube.  Ha ha!  Just kidding, actually if memory serves it's a mere 42" cube.  I hope you are not of a delicate constitution, or lazy like some here who will go unnamed.  That's a block, if you make a slab instead you are making your life worse, not better.

Search the forum for [ahem] 'mount', and pay special attention to the fine photo series referenced by one 'hotater' (no I don't know what that means, but don't laugh he is uncommonly well armed).

[Guy_Incognito]

Well, it's going in when I build a house and builders will be looking after the house slab and other concrete pours, etc etc. - so laziness on my part is not really an issue...

I've done the search and read a fair few posts on the holy block of concrete as a means of vibration dampening and ... I still don't know. There's two questions I have to ask :

1. A ton of concrete will dampen the local movement of the engine, but isn't the same energy transferred outside that block to the surrounding dirt regardless? You've got a certain amount of reciprocating mass thrashing about in your engine and that's where the energy comes from. Whether it gets transmitted through a ton of concrete before being further transmitted through the surrounding soil is a moot issue. I would have thought that the larger block in fact increases the coupling between your thrashing masses and the ground around it.

2. There's talk that bearing/component longevity is increased when bolted to the holy block of concrete and thrashing is reduced to a minimum. Say you've got (shrugs) 5kN of force at a particular instant trying to push your engine block into the dirt and 5kN of force pulling up into the air a half-cycle later. Bolted to a relatively immobile block of concrete, wouldn't that stress all the internal components more than if it was bolted to a flexible mount that moved a little in the downwards direction, then moved a little in the upwards direction? If we take it to the extreme and it was floating in space (or suspended on springs) - there surely would be a lot less internal stress between the block and the reciprocating mass when the whole lot can thrash about as it wants?

This is why I was looking at some sort of rubbery/springy mount that absorbs the energy in one part of the cycle and gives it back later on. Sure, it'll thrash about a bit, but the peak forces transmitted to the ground are then reduced.  I know, the manual says - big cube of concrete. But that was the factory-decreed catch-all solution from nearly a century ago, before there were things like special-purpose rubber dampeners tuned to low frequencies.

But I've plenty of time to play with the system before it goes in "for real", so I might just make the frame and if it's no good, embed it on site in the cube on concrete when the rest of the place gets built.

[Mr X]

Yeseterday I spent the day im my shop . Ihave isolated the engin mount block a bit off my shop slab . On my welding table was a stee ruler and it starting huming to the beat of the Roid Humm. Still much better then when it was sitting on the same slab as the shop. Yes by all means seperate your engine from any building , shop or house. And YES ballance the bastard before you mount it to your block.

Greg

[rocket]

i agree with a good quality rubber mount

[slowspeed1953]

Here are some really bitchin mounts http://www.enidine.com/Airmounts.html their what I plan to use.

Peace&Love , Darren

[Guy_Incognito]

Anyone care to guesstimate the weight of a JKson 6/1 + 5kW ST head in kilograms?

400 or so?

The reason is related to the rubber mounts I'm looking at trying. The company that sells a bajillion rubber mounts has a interesting graph of frequency Vs deflection in their catalogue ( http://www.mackayrubber.com.au/pdf/industweb.pdf )

Basically, to stop a 10Hz vibration from thumping through the bedrock (eg, from unbalanced flywheel at 600rpm) you need at least 12-15mm of static deflection to get 80% dampening.  So assuming a mass of 400kg for the set and frame, 3 mounts that bend 11mm at 150kg each would be pretty good at keeping 10Hz vibrations from imbalanced flywheels from cracking your concrete and brickwork. They won't do much about the 5Hz power strokes though - you'd have to get mounts that deflect a fair bit more to elimninate them. Of course, as others have shown, the more mass you can get attached to the engine and suspended on the mounts the better, so my frame might end up a boxed and filled with concrete for a few hundred kilos more mass.

Anyway, rough guides to weight of an entire setup would be good, as I'll probably just pass all the relevant info onto them and ask them for the best mount for the job.

[Rtqii]

These stationary engines were never designed for flexible mounts. All the industrial/commerical installations of reciprocating equipment for stationary use specifies block mounting systems. I am not saying that flexible mounts are not used or that they may not work... I am saying that the equipment is designed for stationary mounting on an inertial damping block.

There are steps you take during the casting of the mount that isolate the block from any surrounding slab.  From a cost vs etc. standpoint the best solution I have seen is felt or synthetic padding (fuel/grease proof) placed between the block and the surrounding soil. A double thickness is used for the base, and a thinner pad is placed around the sides. If flooring is poured around the block (or vs.), the padding extends up until it is level with the floor of the poured slab preventing direct contact and thereby isolating vibration.

There is commerical padding available that does not cost an arm and a leg and they will pre-cut isolation padding for your pour dimensions... But I wonder if old carpet would not work just as or nearly as well. If fuel or water intrusion is expected to be an issue (think about it), the used waste carpeting can be sealed up in plastic tarp and the resulting pads can then be placed in and around the pour. This is pretty close to a textbook mounting.

I repeat that many people use flexible mounts, I don't think that is the proper way to mount this equipment and I do agree it's more work, time, and possibly expense doing the job right. The payoff may not be noticeable at all... This is a case where you would only be able to directly or indirectly calculate the savings by not doing it right the first time.

Say a main bearing wears out at 500-1000 hours. If you had an improper mount it's easy to blame those cheap Indian bearings.

[rcavictim]

I am also of the opinion that it would be better, reducing peak bearing loads and therefore probably increasing bearing life, by letting the engine boink around a bit on a compliant mount.  You have to provide flex couplers to the exhaust system though if you do.  The water and fuel lines can be rubber so they can take the constant flexing.

I made a floating frame to bolt my VW diesel and ST type head to which floats on 22, SB Chevy valve springs to a heavy box tubing frame filled with sand.  This frame is on HD industrial caster wheels so I can move the plant out of it`s tiny generator room when service is required.  A steel braket bolts the frame to the concrete floor when in operating position so it won`t walk around.  There is no vibration tranfer to the concrete floor.

When I redid my Petter PJ-1 genset I created a similar floating subframe on a heavy wheeled mainframe.  I used some larger valve springs that are likely from a big diesel engine.  The single cylinder Petter is a boinker! The whole engine does a repetitive rotational jerk at every ignition bang due to torque reaction with the massive flywheel.  It does not transfer any vibtration to the floor. At speed it is happy but due to the spring rate and floating mass the engine reaches a mechanical resonance while coating to a stop which causes it to bounce like crazy just at the end as it stops spinning.  This really exercises my corrugated SS flexible exhaust coupler.  If the Petter was bolted to the concrete floor in the shop I have every confidence that I`d be aware of it running in my house 100 feet away.

[Rtqii]

I made a floating frame to bolt my VW diesel...

Great!!! But this engine is not a stationary design, it has no flywheels 

When I redid my Petter PJ-1 genset I created a similar floating subframe on a heavy wheeled mainframe.  I used some larger valve springs that are likely from a big diesel engine.  The single cylinder Petter is a boinker! The whole engine does a repetitive rotational jerk at every ignition bang due to torque reaction with the massive flywheel. 

It's a good thing the bearings are isolated and this vibration, angular torque, and uneven delivery of force is not seen by the moving parts. Right?

If the Petter was bolted to the concrete floor in the shop I have every confidence that I`d be aware of it running in my house 100 feet away....

It's never supposed to be bolted to the floor. Slab floors are not stationary engine mounts either. I just posted that the proper mount is an isolation block... Slabs transmit the vibration. Flexible mounts focus the vibration like a lens right on the loaded bearings.

I find it impossible to see your rationalization that with a stationary engine that is moving about with the rotating parts jigging around on the bearing mounts the bearings see less stress. With the flywheel mass which transportation engines like your VW don't have... I bet the stationary engine is delivering many times the stress to the bearings as opposed to the VW setup.

[albany dbd]

im also of the opinion that a heavy skid on rubber of springs is the best answer. mine is a 5'x3'-6"  h beam fram poured with cement. works great no sound through the floor to house. very little movment at the maybe 1/16" at the top of head. been running pretty much 24-7 for 8 months now no problems.  good luck.

[europachris]

Vibration is a funny thing.  If anyone still listens to vinyl LP's, you can relate to this.  There are two camps of thought - light weight and isolated and very massive and rigid.  The light people use thin platters, suspended by springs, and mount the turntable to a rigid, light stand (or even to the wall of the listening room).  The heavy people use massive platters (4" thick solid acrylic loaded with lead), sand filled plinths (the 'base' of the turntable) and massive stands.  Some even pour concrete blocks in basement listening rooms to mount the turntable too.

It seems the 'massive' camp gets better results.  Even at the microscopic levels of vibration created by the stylus, it works better to have a rigid mount to sink that vibration to rather than trying to suspend and absorb it through springs and such.  It ends up 'reflecting' back to the cartridge/record interface and screwing up the sound.

I think that mounting a Listeroid to a big block is the way to go.  Sink that vibration so something so massive in comparison that it can't go ANYWHERE.   But, that takes a lot of work and thought.  It's also totally not portable, but the Lister was never intended to be portable. 

I wonder if running two engines, one on concrete and one on a flexible mount, would show any difference in life, say after 5000 hours, even 10,000 hours?

Chris

[aqmxv]

That makes sense as far as it goes, but I suspect the best arrangement, as with the turntables, is a slab of rock (granite in the case of the turntable, reinforced concrete for the lister/oid) sitting on a compliant suspension.  This gives you a place to sink the vibration happening on the surface without conducting vibration either way through the suspension.  See also the buildings inside Cheyenne mountain...

[Rtqii]

I think that mounting a Listeroid to a big block is the way to go.  Sink that vibration so something so massive in comparison that it can't go ANYWHERE.   But, that takes a lot of work and thought.  It's also totally not portable, but the Lister was never intended to be portable.

That's the crux... People want to treat the Lister/Listeroid stationary engine as if it was a transportation engine designed to deal with flexible mounts and the resulting movement of the crankcase.  The thing is, they are looking at the wrong type engine. Stationary engines with big flywheels are not transportation engines designed for flex mounts.

You can stationary mount a transportation engine, no problem... Flex mount a stationary engine and you are simply trying to force the wrong engine design to work for you. Get a different engine, or if you don't and you experience failures of moving parts in service put the blame where it belongs, on the obstinate engineer, not the machine or the quality control.