The invention relates to a pump, comprising a housing with a recess in which a pump unit is located. Said pump unit has a pump chamber which is formed by a pump chamber ring and at least one pressure plate positioned on said pump chamber ring; and a rotary-driven pump element which is located in the pump chamber. The pump also comprises a pressure space which is delimited by the recess and the pressure plate. The invention provides that a peripheral distancing means is located between the bearing surfaces of the pump chamber ring and the pressure space-side pressure plates or the chosen radial extension of the pump chamber ring is less than the radial extension of the pressure space-side pressure plate.