The name Feifel will ring a bell for many a Tiger tank fan. Feifel is the name of the air filtration system used on early Tigers, and is named after the engineer, professor Feifel, who pioneered the principle of the cyclone pre-filter. This type of filter was intended for use in very dusty or polluted environments where oil filters alone were ineffective. The filters were initially used on the Tigers of the schwere Panzer-Abteilungen 501 and 504 in North Africa and later also with various units on the eastern front.
The Feifel system consisted of two filter units mounted on either side of the hull rear. Air drawn in by the engine was drawn in at the middle of the engine deck, and was diverted to either of the filter units. Entering the filter, the air is forced to swirl, creating a vortex. While the air can escape on the other end, the dust particles are too heavy to follow the vortex up to the top, eventually dropping to the bottom of the filter housing. The filtered air continues down the other tube, back towards the engine compartment, where it enters the engine’s oil filter. For more details on different types of filters, their use and necessity, see my previous article.
The schematic to the side shows the principle of a cyclonic pre-filter. Each filter unit on the Tiger houses not one, but about 20 of these cyclonic filters working in tandem. For more information and an actual look into the filters, I recommend you look at Byrden’s page on the Feifel filters.
The only Tiger on which the Feifel filters have been preserved can be found in the Tank Museum in Bovington. It is the well-known Tiger 131 of sPzAbt 504. During my last visit, I paid extra attention to this system. What struck me were the unusually shaped pipes. This remarkable angular shape is especially visible on the outer pipes. The inner pipes appear to have been replaced by the museum at some point and don’t resemble the pipes that were fitted at the time of Tiger 131’s capture (see photo below).
I suspected that the hoses were of a special type, unique to the Tiger I, but nothing could be further from the truth. During a visit to the bunkers at Kornwerderzand, the Netherlands, I found several Heeres Einheits Schutzlüfter (HES) filters that use the same type of hose. It therefore appears to be an ‘off-the-shelf’ tube. To my surprise, this type of hose is actually still used for industrial applications to this day. The flexible hose consist of stainless steel, polygonal links. The links interlock as shown in the image below. Depending on how the tube is bent and twisted, the lines along the hose run straight or spiral.
The angular shape gives the links enough integrity to keep their shape even when heavy objects are placed on them. In the image below, one of the Feifel air hoses has ended up under 8.8 cm Panzer grenades while a Tiger is being resupplied. Hint: the tube is just left of the soldier’s arm that is keeping the ammunition from falling down 😉
I will conclude this short examination with a number of photos in which the tubing of the Feifel system is shown particularly well. The first photo shows Tiger 141 of sPzAbt 501 while undergoing an engine change. The second and third photo show the remains of Tiger 833 of the same unit, after it was knocked-out and blown up at Hunt’s Gap.