After month or so building, thinking and building again i finnished my crawler crane. Its completly RC controlled, because i have only one mechanical source of power i needed something that can control the power-switch between different functions. For this i made a multiplexor that can switch between 5 different gears. The multiplexor is controlled via RC unit's steering axle. The functions of crane are: hook up/down, boom up/down, rotate l/r, first caterpillar, second caterpillar and the most tricky function both caterpillars so crane can move in a straight line. The boom is a little under 1 meter in length, the whole crane with boom down measures 1.4 m. Lifting capability is arround 1 kg, i tested it with 1.5 kg but than the pully's gears started to bend Sad . The crane also has an active counterweight, i used the string that pushed boom up and down to also control the counterweight. This way crane can lift more wieght, especially when boom is at it's lowest position. I am quite pleased with end result.