Overload protective system of bulldozer and scarifier

The utility model discloses an overload protective system of a bulldozer and a scarifier. The overload protective system comprises a working pump, a main relief valve, lift control valves, adjustable-angle control valves, single sequence valves, an adjustable-angle oil cylinder, a lift cylinder, a pressure relay, an electromagnetic exchange valve and a return oil filter. The working pump is connected with the return oil filter in an oil cylinder via the lift control valves and the adjustable-angle control valves in sequence, and further via the main relief valve and the return oil filter. The lift control valves are connected with the lift cylinder, and the adjustable-angle control valves are connected with the adjustable-angle oil cylinder. The oil inlet and the oil outlet of the pipeline of the adjustable-angle oil cylinder are respectively and additionally provided with one single sequence valve. The electromagnetic exchange valve is connected between the piston rod end and the piston end of the pipeline o