Exhaust gas recirculation system for a diesel engine

An exhaust gas recirculating system for a diesel engine having an intake manifold and an exhaust manifold, said system comprising:

• conduit means connected to the exhaust manifold and having a first passage for conducting exhaust gas from the exhaust manifold to the atmosphere and a second passage for conducting exhuast gas from the exhaust manifold to the intake manifold;
• first and second valve means including first and second butterfly valves disposed within said first and second passages respectively;
• and
• control means responsive to engine load and operatively connected to said butterfly valves for regulating the recirculation of exhaust gas in relation to said load and including means for interconnecting said butterfly valves in opposite working relationship to effect the closing of the first butterfly valve while the second butterfly valve is being opened, said interconnecting means having a common shaft rotatably carried by said conduit means in transversely extending relation through said first and second passages thereof, and with said butterfly valves being fixedly mounted in predetermined angular relation to one another on said shaft within their respective passages.