Engine exhaust brake system

The invention relates to the technical field of engines, and in particular to an engine exhaust brake system. The engine exhaust brake system comprises a cam, a rocker shaft, an exhaust rocker assembly, a valve bridge assembly and a sealing device. The cam is provided with a base circle, an exhaust lift and a brake lift. The rocker shaft is provided with a brake oil path capable of being connected and disconnected. A rocker body of the exhaust rocker assembly is provided with a first oil way communicated with the brake oil path. An adjusting screw assembly is provided with a brake lift gap adjusting structure. A ball pin assembly is provided with a second oil way which penetrates a first ball pin and an elephant foot and is communicated with the first oil way. A valve bridge body of the valve bridge assembly is provided with an exhaust valve, a main piston, an auxiliary piston and an oil releasing hole. A main piston installing hole is communicated with an auxiliary piston installing hole. The sealing device capable of sealing the oil releasing hole is arranged in the oil releasing hole. A step cavity of the main piston is communicated with the second oil way. An installing hole for installing a brake exhaust valve is formed in the lower end of the auxiliary piston. By means of cooperation of the cam, the rocker assembly and the valve bridge assembly, an engine achieves the two work states of doing positive work and braking.