would be my pick

Anschlag m (Tech) buffer, dog, end position, end stop, limit stop (Begrenzung); catch (Falle, Schnapper); end of stroke (im Zylinder); stop (zum Feststellen); stopper (Sperre)
(© Langenscheidt e-Fachwörterbuch Maschinen- und Anlagenbau 2007 )

Here I would simply use *stop distance*.

Examples

Dental implant milling tool and methods of the use thereof ...
(b) determining a vertical *stop distance* in the cylinder; .... A milling machine is one such device widely used in the dental laboratory profession that ...
www.freepatentsonline.com/5645427.html

Practical Machinist Lathe ... be exactly calculated IF you know the velocity of teh hammer and the "stop distance" including all the resilient flexing etc. ...
www.practicalmachinist.com/ubb/ultimatebb.php/topic/1/13306...

Method of automatically determining a machining range for lathe ...
In the present invention, a machining range for each chucking can be ... The length of the a-b region, i.e., the *abutment distance*, is similarly of a fixed ...
www.freepatentsonline.com/5136903.html