Im putting together my throttle linkage tonight on my mach 1 sky raider and the throttle worked backwards so i figured out on my dx 7 how to reverse the servo and did it and now it works like it should my question is why is this why do sometimes servos need reversed?

UM....

Because they go the wrong way. Servos don't all go the same direction. You will find that the reversing feature on your radio is very helpful.

It really depends on which side of the servo arm you attach your pushrods to and how the servo's are mounted in the plane. It is not uncommon to have to reverse all of them to get the correct throw's. Not a big deal at all. Good Luck, Dave

Servos get installed to best fit in the fuse. Then the direction is adjusted to suit. Turning the servo around never helped me much

Also, some brands of servos turn clockwise when other brands go counter-clockwise in response to the same TX command. The TX has to be able to sort that out for you. The easiest way is for the TX to have a direction switch.

Trust me its better this way! I was around when you had to figure it out first and plan mounting and servo arm location accordingly or buy a different servo in some cases.