Introduction of Aluminum Multiple Pumps Aluminum Multiple external gear pumps have a floating busing with automatic axial clearance compensation. Gear pumps from GRH are used in various industrial applications and have a lot of different functions: from pumping lubricants into lubrication circuits up to transporting fluids for oils and flow media. In almost one hundred years of company history GRH developed and produced gear pumps in numerous types and sizes. Gear pumps are positive displacement rotary pumps used to transport high pressure and high volume flows. Specifications&Dimensions