The maximum momentum p_max in units of  [mc]  reached by a cosmic ray particle as a function of the shock distance R_s in  [kpc]  or time in  [10⁶]    years. Already within a few kpc from the galactic plane (corresponding to a flow time of about 10⁷   years) an almost constant particle momentum is achieved. The squares are calculated due to particle acceleration occurring only at the forward shock, and the diamonds also include the acceleration at the reverse shock.