mookaloid
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| posted on 8/10/09 at 11:51 AM |
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Prop catcher
Just a bit concerned about the recent and seemingly numerous propshaft problems where the prop adapter has come adrift and flailed around causing lots
of damage.
what is the best wat to design a prop catcher for if it does come adrift?
Cheers
Mark
"That thing you're thinking - it wont be that."
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hobbsy
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| posted on 8/10/09 at 11:54 AM |
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Same thing that you need for eating hardcore curries - a ring of steel! 
Seriously though, this does concern me so everything is tippex'ed up and checked regularily.
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blakep82
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| posted on 8/10/09 at 11:55 AM |
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just a couple of steel hoops, made of some flat steel strip, maybe 52mm wide, welded to bottom tunnel rails, and looped over the top. i'd get a
few photos of mine for you , but i don't think i can see them now the engine and gearbox etc is in
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twybrow
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| posted on 8/10/09 at 11:58 AM |
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Where mine failed, Tippex wouldn't have helped - the nut is within the adapter, so only visible if you take the adapter off....
I am making a hoop that is welded onto the upright end of the prop tunnel - it is as close to the adapter as I can get it. It will be boltable, so I
can still get the prop in and out....
That reminds me - I must ring D&F to see if they have repaired it!
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ReMan
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| posted on 8/10/09 at 12:07 PM |
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I was going to put one in mine, as a bolt in stainless U shape tunnel within the tunnel.
But at chassis build stage then I think a load of extra uprights down the tunnel sides would be good? and tidy?
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blakep82
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| posted on 8/10/09 at 12:08 PM |
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not particularly clear, but
 
Description
my tunnel is only made of (i guess) 0.5mm sheet steel, with no tubes at the top.
as a race chassis, they are happy enough with how mine is.
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adithorp
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| posted on 8/10/09 at 12:27 PM |
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The problem with a broken shaft is that if it breaks at the front the wheels continue to drive the shaft around. As long as it's held in line
thats not a major problem. Once the end gets out of line it starts to flail about and destroy things. Fuel lines, tunnel and your legs! All major
hassle to say the least.
To be effective a prop catcher has to be able to keep the broken shaft in line... or as close as possible to in line. The closer the hoop to the prop
then the more effective it'll be (and less strength required). You want something like Blake82's but with a hoop OVER the prop. If
it's close enough it only needs to be 1"x1/8" steel strip.
adrian
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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blakep82
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| posted on 8/10/09 at 12:31 PM |
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mine does go over, its not a very clear photo though.
ideally i suppose you want something under the prop too, if it breaks at the fron't and digs into the road its going to be even messier might
rivet something underneath, or ad something to the gearbox crossmember
if the prop breaks at the back i guess it'll just fall out and end up in the road, so no major promblem
[Edited on 8/10/09 by blakep82]
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rallyingden
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| posted on 8/10/09 at 01:05 PM |
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Mine is going to be a ring of 1/8 by 1" steel just about 1/2" clear all the way round the prop then four "legs" off it bolted
or welded to the tunnel rails. This way if the prop lets go it should just spin in the steel ring and not try to escape from the tunnel
RD
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pewe
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| posted on 8/10/09 at 02:43 PM |
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Mine is a bit like Blake's but nipped in at the bottom just in case the shaft tries to drop down, dig into the road and somersault the whole
car (and before anyone says that's overkill you obviously haven't seen a runaway milk-float inverted by exactly that happening).
Cheers, Pewe 
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adithorp
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| posted on 8/10/09 at 03:59 PM |
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Although pole-vaulting on the end of the prop' isn't desirable, its the prop flailing about that causes damage in most cases. Do a search
and you'll see where prop's have come through the tunnel side and broken bones, cut fuel lines/ripped out looms and started fires, or just
mangled chassis tubes and gearbox casings.
As yours is Blake, I think you'd have problems; Too much room for the prop' to move.
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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matt_claydon
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| posted on 8/10/09 at 06:28 PM |
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quote:
Originally posted by adithorp
As yours is Blake, I think you'd have problems; Too much room for the prop' to move.
Agreed, that will do nothing to prevent flailing - you need something that does not allow the prop to move more than a few cm out of line should one
end come free.
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jambo
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| posted on 8/10/09 at 06:45 PM |
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sorry blake but i think its better you know.
i had my prop let go and the damage and forces involved are huge at the front.
you will need as said something circular and very close to the prop to keep it within the tunnel.
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mookaloid
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| posted on 8/10/09 at 06:57 PM |
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cheers guys
"That thing you're thinking - it wont be that."
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RichardK
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| posted on 8/10/09 at 07:36 PM |
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Is this where I get to try out my newly refurbed tube bender?
Gallery updated 11/01/2011
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blakep82
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| posted on 8/10/09 at 10:50 PM |
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i never put mine in, it was there since it was racing. it was put in by the chassis manufacture, and yes i would prefer it to have been different. but
i do think the actual reality is, no matter what you do, the prop is never going to break exactly where you expect it. the only proper real safew wayt
is to run in through a steel tube from front to back.
anyway, only about 18" of my prop is in the tunnel, the rest is out the back
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