Hello,
After several years of referencing this website, I've decided to post a question I haven't been able to find an answer to.
I'm designing an air brake system for a railroad application which will use automatic slack adjusters which are typically found on over the road trucks/trailers. The slack adjuster acts as a lever arm to rotate a shaft which engages the brake pad to the rail wheel. The slack adjuster mates to the shaft by a 1.5" - 10C SAE spline.
I have a copy of the 28th edition Machinery's Handbook, but can only find dimensional information regarding the internal splines (specifically for broached holes). I can not find any references to what the external dimensions of the shaft splines should be.
SAE J499 makes reference to the shaft dimensions, but only states the following: "The shaft dimensions depend upon the shape and material of the parts, their heat treatment, and methods of machining to give the required fit. The method and amount of "breaking" sharp corners and edges also depend upon the conditions and requirements of each application."
I'm not really sure how to proceed.
I don't believe the application is severe. The slack adjuster can apply ~2,300 lb*ft of torque max to the shaft. The splined length of the slack adjuster is 1.00". The shaft will be ~12 inches in length.
The load cycles will be very low for this application as it is not a rotating assembly like a motor/pump.
I've tried looking for dimensional data on brake cam shafts on semi-trucks/trailers but haven't found anything worthwhile.
Does anyone have any experience with dimensioning SAE external splines?
Thank you,
Zach
thread404-287612
After several years of referencing this website, I've decided to post a question I haven't been able to find an answer to.
I'm designing an air brake system for a railroad application which will use automatic slack adjusters which are typically found on over the road trucks/trailers. The slack adjuster acts as a lever arm to rotate a shaft which engages the brake pad to the rail wheel. The slack adjuster mates to the shaft by a 1.5" - 10C SAE spline.
I have a copy of the 28th edition Machinery's Handbook, but can only find dimensional information regarding the internal splines (specifically for broached holes). I can not find any references to what the external dimensions of the shaft splines should be.
SAE J499 makes reference to the shaft dimensions, but only states the following: "The shaft dimensions depend upon the shape and material of the parts, their heat treatment, and methods of machining to give the required fit. The method and amount of "breaking" sharp corners and edges also depend upon the conditions and requirements of each application."
I'm not really sure how to proceed.
I don't believe the application is severe. The slack adjuster can apply ~2,300 lb*ft of torque max to the shaft. The splined length of the slack adjuster is 1.00". The shaft will be ~12 inches in length.
The load cycles will be very low for this application as it is not a rotating assembly like a motor/pump.
I've tried looking for dimensional data on brake cam shafts on semi-trucks/trailers but haven't found anything worthwhile.
Does anyone have any experience with dimensioning SAE external splines?
Thank you,
Zach
thread404-287612
