Safety Chains?
#16
06-07-2013, 02:19 PM
Posting Guru
I'm not sure how you figured the 11,114 pound load. And I'm not sure how anyone should figure the load. If the only thing the safety chains had to do was apply enough force to smoothly stop the trailer, the load would be a lot less than 11,114. I figure** 3821 pounds to stop a 7500 pound trailer in 200 feet or 5096 pounds to stop it in 150 feet. And you get to divide that between both chains.
BUT!!!!! that's not all the chains have to withstand. They also need to take the impact of when the 7500 pound trailer going 55 mph takes hits the 5000 pound truck going 54 mph. Impact loads with chains are way higher than the static loads. I don't know how to calculate what that would be, but it'd take strong attachment points.
** (for other geeks that want to know how I figured:
(55 miles/hour)*(5280 feet/mile)*(1/3600 hours/second)=81 ft/sec
(change in velocity)^2=2a(change in displacement)
(81 ft/sec)^2=2a(200 feet)
a=16.4 ft/sec^2 ("a" is acceleration)
weight=mass * g ("g" is acceleration due to gravity = 32.2 ft/sec^2)
7500 pounds = mass * 32.2 ft/sec^2
mass = 233 slugs (yes, slugs. Slugs are the main reason engineers like the metric system)
Force=mass * acceleration
=233 slugs * 16.4 ft/sec^2
= 3821 pounds
BUT!!!!! that's not all the chains have to withstand. They also need to take the impact of when the 7500 pound trailer going 55 mph takes hits the 5000 pound truck going 54 mph. Impact loads with chains are way higher than the static loads. I don't know how to calculate what that would be, but it'd take strong attachment points.
** (for other geeks that want to know how I figured:
(55 miles/hour)*(5280 feet/mile)*(1/3600 hours/second)=81 ft/sec
(change in velocity)^2=2a(change in displacement)
(81 ft/sec)^2=2a(200 feet)
a=16.4 ft/sec^2 ("a" is acceleration)
weight=mass * g ("g" is acceleration due to gravity = 32.2 ft/sec^2)
7500 pounds = mass * 32.2 ft/sec^2
mass = 233 slugs (yes, slugs. Slugs are the main reason engineers like the metric system)
Force=mass * acceleration
=233 slugs * 16.4 ft/sec^2
= 3821 pounds
#18
06-08-2013, 08:18 PM
Logistics Pro
#19
06-10-2013, 08:06 AM
Join Date: Apr 2013
Location: South Dakota
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Well we went camping in the rain this weekend and I towed the camper out with my moms dodge 1500 and pulled it home with my F250. There were a couple of hills and the dodge did not like it very much. I will have to adjust the brake controller a little and it will be fine.
For the safety chains I hooked them up to the brace for the bumper. It wasn't quite level on the trailer but when I get new tires it will just about level it out.
I used my moms truck to pull it out because I could have it all hooked up and ready to go a couple days before we left to go camping. I started to hook the camper up to my moms pickup and the jack couldn't go low enough. So I hooked it up to my truck and took a couple blocks out from under the jack and then hooked it up to my moms truck. I measured and my moms truck dropped 4 1/2 inches my truck only dropped an 1 1/2.
Thanks for all your help guys.
For the safety chains I hooked them up to the brace for the bumper. It wasn't quite level on the trailer but when I get new tires it will just about level it out.
I used my moms truck to pull it out because I could have it all hooked up and ready to go a couple days before we left to go camping. I started to hook the camper up to my moms pickup and the jack couldn't go low enough. So I hooked it up to my truck and took a couple blocks out from under the jack and then hooked it up to my moms truck. I measured and my moms truck dropped 4 1/2 inches my truck only dropped an 1 1/2.
Thanks for all your help guys.
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