Defective Gearbox/Crank assembly

Advert

New Replies

Report Bug

Help/FAQs

Defective Gearbox/Crank assembly

This topic has 32 replies, 18 voices, and was last updated 1 September 2013 at 11:22 by Sub Mandrel.

Viewing 25 posts - 1 through 25 (of 33 total)

1 2 →

Author

Posts
8 January 2013 at 18:52 #108226
Chris Beck
Participant
@chrisbeck31522
As an assignment, I've been asked to compile information on how the attached model works, pick out 30 defects in the model and its design and then comment on how it can be designed better.

I'm not so hot on automotive and transmission engineering so I'm finding it a bit difficult- any helpful comments would be amazing.
Advert

8 January 2013 at 18:52 #21148
Chris Beck
Participant
@chrisbeck31522
CAD Technical drawing of a defective gearbox/crank assembly
9 March 2013 at 22:00 #114099
mike mcdermid
Participant
@mikemcdermid41977
which attached model?
10 March 2013 at 01:05 #114103
Bazyle
Participant
@bazyle
when is the assignment due?
10 March 2013 at 10:33 #114117
FMES
Participant
@fmes
Come on Chris, the suspense is horrendous
10 March 2013 at 10:52 #114118
Les Jones 1
Participant
@lesjones1
Chris,

Many of us have lathes and milling machines etc but I do not know of any of the people on this forum with a crystal ball !

Les.
10 March 2013 at 11:33 #114124
Sub Mandrel
Participant
@submandrel
Chris,

We won't do your assignment for you, but if you can give us a drawing and tell us what your thoughts are, we can help make sure you are on the right track.

Neil
10 March 2013 at 15:46 #114148
Ian P
Participant
@ianp
Chris

I can see about four things wrong with your model. The second drawing of the gearbox shows that the layshaft is misaligned, also the sump plug has a different thread form than the hole it fits into. Better drawings would help, or can you post a link to the virtual model?
10 March 2013 at 16:07 #114150
Jeff Dayman
Participant
@jeffdayman43397
I guess Ian Philips has a crystal ball. As for me I can see no drawing or attachment or link. Must have my clairvoyant receiver/demodulator on the wrong frequency.
10 March 2013 at 18:49 #114156
Speedy Builder5
Participant
@speedybuilder5
Is it those adverts covering up the photos again ?
10 March 2013 at 23:18 #114164
Jens Eirik Skogstad 1
Participant
@jenseirikskogstad1
Lots of questions and no answers from Chris Beck .. Chris, come with photo and explain more clearly and understanding so we may assist you.
11 March 2013 at 10:36 #114179
roy entwistle
Participant
@royentwistle24699
Can I also suggest that you check whether the sump plug washer is left or right hand
11 March 2013 at 10:52 #114181
Sub Mandrel
Participant
@submandrel
If the if the depilatory vane obscures the thrunkling valve there could be problems when the queech obulates.

Neil
11 March 2013 at 11:07 #114182
Ian P
Participant
@ianp
Posted by Stub Mandrel on 11/03/2013 10:52:24:

If the if the depilatory vane obscures the thrunkling valve there could be problems when the queech obulates.

Neil

Neil, wrong! None of that applies to an ecipieclip gearbox.

Seriously though, its (mildly) annoying when a poster poses a question and then just disappears.

I think rather than having moderators checking every posting it would be better if members had to put more effort into the initial registration in the first place, (at least provide 'Location', a minimum 'Profile' etc). Their first post could/should be moderated but further intervention being needed is then unlikely.

It would not totally prevent spam but (if Mr Beck exists) it might save members from pondering on pointless projects, (or helping with homework!)

Ian
11 March 2013 at 11:19 #114183
Sub Mandrel
Participant
@submandrel
I don't know which is more annoying, spam or people who ask but don't come back (unless its people who as for help with homework AND don't come back!)

I'm just grateful that my memory hasn't led me astray. Years ago I googled 'queech obulates' and got no results. Today it returns 43 hits!

It's a line from a brain teaser that was in one of the modelling magazines (RC&ME, Model Boats?) when was a teenager and it's never gone away from my mind! But the web has resurrected it at last!

At least it's something to do – I'm off work with the lurgy today and haven't felt up to any machining since the middle of last week

Neil
11 March 2013 at 12:15 #114185
Springbok
Participant
@springbok
Moderator

Could you not just delete this whole thread as seem pointless
11 March 2013 at 12:28 #114187
Ian P
Participant
@ianp
Posted by Springbok on 11/03/2013 12:15:47:

Moderator

Could you not just delete this whole thread as seem pointless

Thats a bit drastic, after all Chris Beck might have started this thread with genuine intentions but then, for whatever reason (illness, accident, military service, powercut, call of nature?) might have been unable to get back to his computer.

Ian
11 March 2013 at 12:50 #114189
Keith Long
Participant
@keithlong89920
I'm with Ian on this – it's giving contibuters a place for a bit of harmless fun and it's not compulsory to read it. If Chris Beck comes back with a response you'll know without opening the thread as his name will show in the list as the latest contibutor.

I suspect that the truth is that Chris sent the original enquiry to the wrong forum, probably intended it for one on engineering modelling (ie CAD et al) not model engineering.

Keith
11 March 2013 at 13:16 #114191
JasonB
Moderator
@jasonb
Chris may well come back so its best left up, after all he is probably at school/college right now.

I suspect the problem lies with the difficulties of attaching anything to threads on this forum and he gave up trying.

Best thing to do now is ignore the thread unless Chris can add the missing info. That way it will just go to the bottom of the list and people won't go looking at it thinking something useful has been added only to find silly answers

J

Edited By JasonB on 11/03/2013 13:32:43
14 March 2013 at 16:28 #114448
Brad Christian
Participant
@bradchristian60007
Hi all, I think I may be on the same assignment I can link some photo's for you.. bare with me.

Brad
25 March 2013 at 17:36 #115270
Brad Christian
Participant
@bradchristian60007
25 March 2013 at 17:50 #115273
Ian P
Participant
@ianp
Well!

I think Brad is on the same assignment as the mysterious Chris Beck so at least we know what the drawings look like.

What we don't know is what the assignment is for, and therefore whether we would be doing someones homework (or their job!).

I don't mind helping with homework but I think if this thread is to continue then the OP should have the grace to explain why he is asking the question.

Ian
25 March 2013 at 18:06 #115276
Jeff Dayman
Participant
@jeffdayman43397
Holy smokes! someone dreamed up a real clanger with that assembly. Where do we start? There's a lot more than 30 things wrong that I see….

A good general technique to figure out whether an assembly will even go together is to make paper tracings of the parts and slide them past each other on the assembly to see if they clear. Old fashioned, yes, but cheap and it works.

Another hint is that with rotating machinery for power transmission, each part attached to a shaft needs to be located (usually with a male/female cylinder to cylinder or cone to cone fit) and prevented from rotating relative to each other some way, like keys or dowels or ribs in slots.

It wouldn't hurt to read up on stress / strength in flywheels either – machinery's handbook has a good section about that.

It would be nice if our picture poster and the OP told us what class this is for and why they are asking the forum to chime in.

JD
25 March 2013 at 18:50 #115279
Sub Mandrel
Participant
@submandrel
Thanks Brad,

I was expecting super duper CAD drawings – I guess this quiz has been handed down through generations!

I can see parts poorly located, wrongly fitted, over-sized, under-sized. There are ill-proportioned fittings and poorly designed joints, challenging machining operations and just plain bad design.

With the warning that I'm not a trained engineer, iI suggest you ask yourself:
- How does each of the parts move – will they clash or can they shift from their designed position?
- Are bearings correctly chosen and oriented for their designed loads.
- How would you machine each part – are there things getting in the way that cold be designed out?
- Look at the proportions of parts – is anythhing oversized or undersized relative to other parts carrying similar loads.
- Where would stress concentrate in the design – are there sharp internal corners or thin sections in these places?
- What makes an efficient flywheel?
- Could anything be changed to make assembly easier?
- How are parts mated together – do they have reliable secure joints where fixings just keep them secure, or do the fixings carry the loads?
Go through that list and you should be getting near your 20 things.

Neil
17 April 2013 at 10:52 #117141
Brad Christian
Participant
@bradchristian60007
Sorry for the lack of response I've had a few exams to prepare for but now I can get back to the assignment. A few people wanted to know what this assignment is actually for: it's a university assignment worth a small percentage of our overall grade.

Thanks for the replies so far. I think my problem is that I have had no experience with CAD or with gearboxes/crankshafts and so I am having trouble determining what alot of the parts even are which makes it difficult to judge if the parts should/shouldn't be there or are over/under sized etc (this is definitely not my speciality).
Author

Posts