It's because reverse in on a gear with a chain if you pull in reverse you will break your chain

 

^ Correct, but if someone is stuck and you have a winch you can winch them out in by only use the winch's power, put your brakes on while in neutral and do your winching. Try not to do it while in park as you could mess up your transmission that way too, also why you should have a parking brake for hauling your machine.

 

I would not recommend pulling in either direction, can slip and burn your belt in either and then the reverse chain as mentioned. Only winch them out.

Can't tell you how many stories I have heard about the above while pulling someone else out and that person does not pay for your damage while doing them a favor

Todd

 

Its good practice to not pull hard in reverse in any vehicle. The gears are simply not as strong going backwards. It will work but, not good practice.

 

Thanks all for the input. Very valuable information. My friend wasn't exactly sure which machines it was, he doesn't own one just heard about it. I guess they are atv's not tractors Thanks again!