STEERING DESCRIPTION AND OPERATION 57-25 Simultaneously, the fluid pressure outlet to the pressurised axial grooves are restricted or partially restricted by the closing return fluid control edges. The fluid displaced by the piston from the right power assist cylinder chamber, flows through an external pipe to the radial grooves. From there the fluid passes to the associated axial grooves and onto the return fluid control grooves, via the further opened return fluid control edges. The return flow of fluid to the reservoir passes via interconnecting bores which lead to the return fluid chamber. When the steering wheel is turned to the left the operating sequence is as above but the pressure is applied to the opposite side of the piston.