The utility model discloses a low -cost three ball instrument convenient to assemble, including base, sun model,
earth model, moon model, still include drive arrangement, multistage drive gear group, multistage drive gear group includes primary gear group, secondary gear group,
tertiary gear group, be provided with bottom support and bottom disc tooth on the base, and have transmission lower mounting bracket, transmission upper mounting box through bottom support installation connection, primary gear group drives
earth model rotation, secondary gear group drives moon model rotation, transmission lower mounting bracket is installed respectively with upper linkage gear, lower linkage gear, and multistage drive gear group drives relative between lower linkage gear and bottom disc tooth, so that
earth model, moon model rotates around sun model, the transmission structure design convenient to assemble connection of the utility model design can choose the free assembling mode of board material, realizes the low -cost use of three ball instrument, and can realize three ball instrument model various use function's demonstration, and the utility model discloses convenient for popularization and use.