A cylinder or other part that has an upwards and downwards stroke will have a motionless point at the end of its stroke, where the direction of the motion changes. It is 'dead' at this point, at both the top and the bottom of its stroke. The English source uses a clumsy-ish construction instead of the precise and unambiguous technical term for this piston position. The correct English term for this position is Bottom Dead Centre or BDP. (There is also Top Dead Centre or TDC; 'Bovenste Dode Punt or 'BDP' in Dutch.) One of the reasons that there are specific terms for these piston positions is that TDC, for instance, or a number of stated degrees before or after it, is often stated as the measure of timing of spark ignition or valve opening/closing in an internal combustion engine or pump, etc. A TDC or BDC position may also be necessary for de-mounting or cleaning processes, etc. See first URL below for Dutch reference to both positions.

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Note added at 2 hrs (2018-11-02 19:40:47 GMT)
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I suppose one could also say ' . . op Onderste Dode Punt van de [baler] slag'. (Caps optional.)