The lat pull down machine is a great way for beginners and intermediate people to learn how to use their back muscles properly so that once sufficient strength is acquired, pull-ups and chin-ups can be performed with proper form. In my experience using the lat pull down machine is the fastest way to teach proper technique transition to make pull-ups quickly.
Here is a video we shot of the lat pull down in use. The cool thing about this particular machine is that the weight that you lift corresponds to the real force you exert. Sometimes machines use complicated pulley systems that actually halve the weight being lifted. This is not the case here.