Stub Axle Capacity

Submitted: Thursday, Jul 17, 2014 at 12:35
ThreadID: 108776 Views:3042 Replies:8 FollowUps:8
This Thread has been Archived
I need to make up an axle using square hollow section (SHS) with a stub axle each end. I know the stubs have a set capacity. the problem I have is that I cannot find a calculation or chart that will identify the correct size of SHS I need to maintain the capacity of the stubs. The last thing I want is the SHS to bend in the middle. Can anyone help me?
Back Expand Un-Read 0 Moderator

Reply By: Thinkin - Thursday, Jul 17, 2014 at 13:23

Thursday, Jul 17, 2014 at 13:23
hi, What size stubs are you talking about, 40,45,50mm cross section? Why do you need (SHS), abnormal width or some other reason? What size SHS have you got in mind? Just asking, there may be some other solution to your question.
According to the trailer axle parts suppliers any welding of axle parts must be pre and post heated. check it out on www.trailerparts.net.au
cheers Alpero
AnswerID: 536185

Reply By: Nomadic Navara - Thursday, Jul 17, 2014 at 20:03

Thursday, Jul 17, 2014 at 20:03
Apart from some low capacity round axles, all the axles I have seen have been solid section sections. What makes you think you will get much capacity out of hollow section? What sort of capacity are you expecting to achieve?
PeterD
Retired radio and electronics technician

Lifetime Member
My Profile  Send Message

AnswerID: 536210

Reply By: Member - KeithB - Thursday, Jul 17, 2014 at 23:22

Thursday, Jul 17, 2014 at 23:22
It will depend on the weight you want to carry and the distance between the wheel centre and the centre of the spring. There is a free program you can use called Beamboy that will calculate the maximum tress and deflection for you, but you will need a little engineering experience to make it work. Maximim stress should be the yield point of the steel divided by 5.

I am building a two tonne (loaded) off road van on a single axle and found that 75 x 75 x 6 was a bit marginal for my setup do I upgraded to 100 x 100 x 9 which was overkill, but eliminated any worry.

I had a local engineering shop turn up some heavy plates to take the stub and disc brake assembly from a 79 series Landcruiser. I wonder whether welding stub axles is a good idea, but it make be OK for light trailers if done well.


AnswerID: 536222

Reply By: Troopy8thwonderoftheworld - Thursday, Jul 17, 2014 at 23:23

Thursday, Jul 17, 2014 at 23:23
I am in favour of using the stub and RHS method and have made over 100 axles this way with out any problems,some of my reasoning is as follows a section of steel gets 90% of its strength from the outside 10%.most standard solid axles are imported and made from rubbish steel and most are bent or out of shape, where a good stub is made from a higher grade steel with more accurate tolerances , less than half the unsprung weight! and 50% stronger when using 50x50x5 SHS
That's my 5c worth
AnswerID: 536223

Reply By: olcoolone - Friday, Jul 18, 2014 at 09:35

Friday, Jul 18, 2014 at 09:35
Why don't you get a specialist to make them up for you, they are not that expensive.

I am not personally having an attach at you but when you have to ask on a forum it indicates you have no experience or very little in fabrication.

The other aspect of it is the safety side, have a poorly welded, designed or fabricated axle can cost lives and life long injuries and if it is something you have done with no experience it can lead to big legal or financial implications and imprisonment.

As I said above axles are cheap to get made and at least you have something to fall back on if it did go pear shaped.

AnswerID: 536233

Follow Up By: Whirlwinder - Friday, Jul 18, 2014 at 17:38

Friday, Jul 18, 2014 at 17:38
Yep, what he said for sure. It might be me coming the other way when the stub breaks off!!
0
FollowupID: 820329

Follow Up By: Hairy (NT) - Saturday, Jul 19, 2014 at 11:48

Saturday, Jul 19, 2014 at 11:48
He might be a brilliant welder and even qualified for all we know, he just wants advice on material size.
I always though asking questions when not 100% sure was the safest option?
0
FollowupID: 820356

Follow Up By: olcoolone - Saturday, Jul 19, 2014 at 12:42

Saturday, Jul 19, 2014 at 12:42
Yeap and what happens if he gets the wrong advise of a forum that he has taken as being 100% correct.

If he had fabrication experience he would know where to get the information and how to calculate to get the desired results.

Yes asking questions when not 100% sure is very sound advice..... but not on a general "everyonesanexpert" forum.

Sorry I put safety, lives and risk as a priority, you may think different.
0
FollowupID: 820357

Follow Up By: Hairy (NT) - Saturday, Jul 19, 2014 at 20:10

Saturday, Jul 19, 2014 at 20:10
No I don't think differently in that aspect at all....I just assume the bloke is intelligent enough to work out the difference between good and bad information.......
0
FollowupID: 820380

Follow Up By: olcoolone - Sunday, Jul 20, 2014 at 09:28

Sunday, Jul 20, 2014 at 09:28
How do you know he is intelligent enough to work out the difference between good and bad information.......??????

If someone doesn't have the intelligence to work something out or knows where to obtain and calculate the information to validate it's correct then who do they know if it is correct?

Your talking engineering..... oh that's right everyones an expert.

If he knew he would not be asking the question........ again your talking about something that has to be 100% and if not someone could DIE or be INJURED from his mistake....... oh sorry mate forgot to carry the 1.

One thing I have learnt that some seem not to understand..... never think someone has the same skills sets then you and treat everyone with doubt.

Sorry it's safety and not stupidity.
0
FollowupID: 820395

Follow Up By: Hairy (NT) - Sunday, Jul 20, 2014 at 11:52

Sunday, Jul 20, 2014 at 11:52
Hahahahaha......."how do you know he's intelligent?" How do you know he's not? And being he's asking questions is a bloody good start.
I assume you don't even change your own tyres as that too could cause an accident if not done properly and is about as complicated as welding up an axle to a competent welder.

Just because he doesn't know the material size doesn't make him stupid or dangerous.........he could quite easily over engineer it and drag around a heap of weight he doesn't need.
Correctly welding an appropriate stub axle to an underrated axle would probably result in a bent axle, not an out of control wheel causing death and gloom..........besides he's asking questions to avoid this.
Do you know of an online load calculator? Have any reliable charts or have an engineering degree yourself? Know any one who may be able to help? Do you own a similar set up and can measure your axle and tell him what has worked for you?........If so help him.......that's what forums are for.......if not let some one who can. Im a qualified Boilermaker/Welder and have made dozens of axles for trailers, trucks, aircraft ground control equipment, and even bomb carriers and I don't know exactly what size axle to use........I ask someone who does. Just like this bloke is doing.
"One thing I have learnt that some seem not to understand..... If you cant say something nice (or helpful), don't say anything at all.

Cheers
1
FollowupID: 820405

Follow Up By: olcoolone - Monday, Jul 21, 2014 at 21:05

Monday, Jul 21, 2014 at 21:05
Wouldn't have a clue about welding...... But I can tell you what AS1796 is and what's involved in Cert 1 - 9 and how stressful it can be..... Sorry cannot help you with Cert 10 as I have no need for it.

Being a boiler maker you should be more them qualified to provide the information he needs an having a good understanding of metal processes provide the guidance he needs.
0
FollowupID: 820477

Reply By: Slow one - Sunday, Jul 20, 2014 at 12:01

Sunday, Jul 20, 2014 at 12:01
Adrian,
Now to answer the question you actually asked.

Here is a bearing and axle load calculator.

Axle & bearing chart
AnswerID: 536320

Reply By: Hairy (NT) - Sunday, Jul 20, 2014 at 12:07

Sunday, Jul 20, 2014 at 12:07
Gday,
Most steel manufacturers wont give out that sort of information these days for liability reasons, but if you have an engineering mob or even better a trailer manufacturer close by , I would pay them a visit. They can be quite helpful if asked politely.

Cheers
AnswerID: 536321

Follow Up By: Hairy (NT) - Sunday, Jul 20, 2014 at 12:14

Sunday, Jul 20, 2014 at 12:14
Might help
0
FollowupID: 820406

Reply By: Adrian L - Tuesday, Jul 22, 2014 at 08:52

Tuesday, Jul 22, 2014 at 08:52
Thanks KeithB and Slow One! I greatly appreciate your feedback and your ability to read the question I posed. I assumed I was intelligent enough to pose a simple question with a bit of background and get a simple answer. yes - there is a calculation or chart at..... or No there are no calculation or chart on the web! Obviously the question was beyond the intellectual ability of some respondents!
AnswerID: 536403

Sponsored Links

Popular Products (13)