A pneumatically driven piston pump and its quick exhaust slide valves, which allows air to be evacuated from the piston pump's piston chambers directly into the environment without having to pass through the main distributor valve, in such a way that it does not cause a drop in temperature due to the expansion of the compressed air which freezes the humidity of the air itself, clogging the compressed air circulation ducts and causing the pump to shut down or stall. Such an air-operated piston pump with quick exhaust valves allows the passage of air with low restriction, which increases the efficiency of the piston pump and decreases its compressed air consumption compared to the same air motor without quick exhaust valves.