module gearbox(shaft1,shaft2);
 inout shaft1,shaft2;
 rotational_omega shaft1,shaft2;

 parameter real radius1 =1  from (0:inf),
                inertia1=1m from [0:inf),
                radius2 =1  from (0:inf),
                inertia2=1m from [0:inf);

 analog
 begin
    // Calculate angular velocity of shaft1 from angular velocity of shaft2.
    Omega(shaft1) <+ Omega(shaft2)*radius2/radius1;

    // Calculate shaft2 torque from shaft1 torque and angular acceleration.
    Tau(shaft2) <+ inertia2*ddt(Omega(shaft2));
    Tau(shaft2) <+ (Tau(shaft1) - inertia1*ddt(Omega(shaft1)))
                           *(radius2/radius1);
 end
endmodule