Posted by Paul Cook in Kempner, Texas on Tuesday, August 08, 2006 at 6:23PM :
In Reply to: Anchoring PW to Trailers. Options? posted by Dale on Monday, August 07, 2006 at 10:24PM :
As a Movements Officer responsible for rail and air loading military vehicles and equipment, I went to the appropriate vehicle manuals back then, and again just now.
Because the Army did not trailer prime movers in road marches, the only relevant information in the manuals covers shipping on rail cars.
Both TM 9-808 for the 3/4 ton WC and TM 9-8030 for the M-37 specify securing these vehicles using wheel chocks to control forward and rearward movement and then securing the wheels and axles to the flatcar. This method allowed the vewhicles to ride on their own springs. Because chain tie downs could never be tightened enough to eliminate all the suspension flex, securing the wheels and axles avoided the shock that resulted when the vehicle movement compressed the springs and then the vehicle rebounded against chain tie downs. A jerking "hard" tie down may be damaged or break. There is also the possibility of damage to the vehicle being transported.
Tracked vehicles and heavy wheeled vehicles used the crossed chains with great tension applied to the vehicle suspensions. These vehicles, by the nature of their suspensions, were not as likely to move downward and then rebound against the chain tie downs.
When I first started hauling with my "go to Iowa with one - come home with two" trailer, I used crossed chains. I could feel the vehicles rebounding against the chains even in the towing truck. Also, the tie downs were always working loose. I had to take up slack at every stop even when using the easily adjusted ratchet style chain binders.
That's when I got out the Army manuals and changed to securing the wheels and axles. I also remembered why trailer beds are wood. That's so you can nail down the proper wheel chocks. Once I switched to this method, I no longer had the rebound induced jerking, and the tie downs stayed tight.
That's my crusty old opinion.
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