tks
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| posted on 9/11/07 at 11:59 AM |
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Transmission expert needed
Hi,
as some of you are aware of i build an transmission box to couple my VFR 800 to an central laying drive shaft.
Well the good news is that it works 
the bad news is that the box is made of alloy and that it heats up allot!
You cant touch it with your fingers.
What i want to know is where comes that heat from?
i know the box is on the entrance of the tunnel sow catching allot of hot air from the engine and the rad.
but also these 2 things do apply.
- its filled up with oil not completely but quet allot
- its hermaticly closed (no breather)
could both upper things result in hot oil resulting in a hot case?
i now that oil generates friction (the chain is passing in the oil with speeds upto 120Km/h)
what are the thoughts?
Tks
p.d. the reason for not thingking about mechanical friction is the fact that i have used it an hour sow i don't think any thing would last that
long.
[Edited on 9/11/07 by tks]
The above comments are always meant to be from the above persons perspective.
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coozer
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| posted on 9/11/07 at 12:11 PM |
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Probably from meshing gears, lack of backlash or poor alignment.
1972 V8 Jago
1980 Z750
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tks
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| posted on 9/11/07 at 12:16 PM |
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It has chain gears and an chain.
Sow not much friction i would guess
Tks
The above comments are always meant to be from the above persons perspective.
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Howlor
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| posted on 9/11/07 at 12:17 PM |
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Can you turn it by hand easily?
If there is any side thrust placed on the shafts then this may increase the torque required hence friction involved and heat.
Is there any wear on the parts showing possible issues?
How about a WRC style diff cooler fitted.
Steve
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Howlor
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| posted on 9/11/07 at 12:18 PM |
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Having never run a Quaife reverse box possibly some of the other team may be able to comment how hot they run?
Steve
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tks
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| posted on 9/11/07 at 12:25 PM |
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yeah i will open it up and take a look at some things.
the bearings used can cope with 18KN dynamic load on them. Sideways i have no idea.
saying that everything is in oil! we thought about the oil that maybe the chain generates the heat being slowndown by the oil.
its like putting a blender to blend in liquid it will be slown down by the liquid and eventually heat it up coudn't it?
Tks
woud any thing not good made last one hour 80BHP?? the chain speeds vary from 0km/h to 60km/h i guess...
Tks
The above comments are always meant to be from the above persons perspective.
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Howlor
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| posted on 9/11/07 at 12:32 PM |
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Generally chains don't require oil immersion so it may be possible to run a much lower level to reduce the friction.
When you consider diffs they run quite hot and they are only meshing the gears. It may be that it is ok.
It will be interesting to see what BHP you get on a rolling road becasue this will tell you the losses that you are suffering in your total
transmission. The other guys running this engine should be able to give you comparative data of bhp at the wheels.
Steve
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matt_claydon
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| posted on 9/11/07 at 12:42 PM |
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Looking at it another way, suppose you are putting out 50kW from the engine and the transmission has 10% loss, then you are putting 5kW into the
gearbox as heat - that would certainly warm it up somewhat!
I have no clue if these figures are realistic but they can't be far off.
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Howlor
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| posted on 9/11/07 at 12:47 PM |
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quote:
Originally posted by matt_claydon
Looking at it another way, suppose you are putting out 50kW from the engine and the transmission has 10% loss, then you are putting 5kW into the
gearbox as heat - that would certainly warm it up somewhat!
I have no clue if these figures are realistic but they can't be far off.
Over here at the moment we would be looking to harness that with a lovely foot blower!
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Phil.J
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| posted on 9/11/07 at 01:21 PM |
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Chains can generate alot of heat. A very short chain on mid engined bike engine installations can glow red hot.
Running immersed in oil will help dissipate the heat, but a small circultion pump together with an oil cooler will help greatly
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Dingz
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| posted on 9/11/07 at 01:35 PM |
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Also add a breather as the temperature build up will create quite a pressure inside the box and possibly push oil past the seals.
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tks
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| posted on 9/11/07 at 01:38 PM |
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quote:
Originally posted by Dingz
Also add a breather as the temperature build up will create quite a pressure inside the box and possibly push oil past the seals.
yeah thats a good one, but it didn't happend yet...
The above comments are always meant to be from the above persons perspective.
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