Abstract: A percussive rock drill bit includes a head having an annular gauge collar and a central island. An annular cutting channel is defined between the collar and the island such that specifically positioned cutting buttons are effective to create an annular ridge in the cut rock face having a reduced rock breaking resistance to increase the rate of drilling and/or decrease the required power consumption.

Abstract: The present invention relates to a combustion engine, comprising an intake system having a throttle valve controlling an air flow to the combustion engine, a brake booster being in fluid communication with the intake system, downstream the throttle valve, via an evacuation duct for evacuation of air from the brake booster to the intake system, a crankcase being in fluid communication with the intake system, downstream the throttle valve, via a low load duct for conducting crankcase gases to the intake system, a venturi tube forming part of the low load duct, wherein the venturi tube comprises a narrow venturi tube portion forming a flow resistance within the low load duct through which the crankcase gases have to pass, wherein the evacuation duct is also fluidly connected to the venturi tube portion, via a connection duct, for further evacuation of air from the brake booster to the intake system.