Tiger engines were difficult to start after cold nights. Several solutions were provided, culminating in a system called Fuchsgerät (Flue Equipment). It allowed the engine's cooling water to be heated by a standard German blowtorch, like these ones.
The equipment was installed in the engine compartment, to the lower left of the engine. The flames were directed through a new port in the tank's rear wall. This is the port seen from the inside. We are in the Sturmtiger at Munster museum. [3] .
Inside the hull, the flames passed through a hollow sleeve that carried the engine's cooling water. This diagram is from a German original, showing the Fuchsgerät in a Tiger E. We are looking from the left side of the tank. The flames from the blowtorch were ultimately emitted through the sheet-metal flue at the top left of the diagram, into the engine compartment.
In the rusting wreck of a Tiger (at Snegiri [5] ) we can see the flue. It was made narrow so that it would fit between the engine and the compartment wall.
Back in the Sturmtiger, we can see that in this vehicle someone has flame-cut the edge of a structural plate (indicated by an arrow) to make more room for the flue. At top center of the photo is a support for a fan-drive gearbox. This existed in Tigers long before it was used to support the flue.
Before using the Fuchsgerät, the crewman would move two butterfly valves; one would close the water pipe leading from the engine to the radiators, and the other would open a bypass pipe leading to the Fuchsgerät sleeve. In the first German diagram, a lever that controls both valves is arrowed. This more detailed diagram shows the Cardan cable that moves the lever.
This schematic shows how the heater and the valve related to the rest of the cooling-water system. When the heater was used, the engine was not turning and the therefore the pump did not work. The hot water would flow in the reverse direction, driven by convection.
These two drawings show the two positions of the lever. To use the heater, one would pull the lever forward by means of the cable. To return to normal operation, one would release it; it had a spring that returned it to its default position. The amount of travel was 75mm.
In these German photos of HL230 engines, we can see the "lever for controlling the cooling water". These early examples have a V-shape slightly different to what was drawn above.
In this engine (from the Tiger B in Bovington) we can see the later version of the lever, marked 'A'. The valves are integrated into the rear cap of the oil cooler. The bypass pipe, of 40mm diameter, connects at 'B'. The main water pipe to the radiators, of 80mm diameter, connects at 'C'.
The lever's control cable originally ended in the firewall of the tank, with a knob accessible from the crew compartment. To enable the use of the Fuchsgerät, the crew would pull this knob by 75mm. This example is in a Late Tiger at Saumur museum. It is crudely labelled "Fuchsgerät offen / Knopf gezogen zu" ("Flue device open / knob pulled" ).
And this one is in the same Sturmtiger mentioned above.
The valve was useful even when the motor was running, because it controlled the path by which water could bypass the radiators, thus it influenced the engine temperature. The system was therefore improved in May 1944, starting with chassis 251166 [2, see 3.4.1.1] , by extending the control cable forward to where the driver could use it. This German diagram shows the final layout for the control cable.
The cable now terminated in a rotating lever on the wall to the driver's left, allowing fine control of the bypass. This example is in a Tiger B, but equipment for the Tiger E (and Panther) was identical. I believe this example has been installed incorrectly, and the cable should be to the left of the lever rather than the right.
Behind the faceplate is a round box. The cable passes through the side of the box, and the seath within the box is cut open. The core of the cable is brought out through the cut and wrapped at least once around the axle of the lever. Thus, turning the lever pulls the cable core out of the seath on one side, and pushes it in on the other. This self-contained arrangement is quite robust and does not expose the cable core.
Here, the lever enables the Fuchsgerät; the pointer is at the position labelled 'Vorwarmer'. The lever can be rotated anticlockwise by a half turn. The pointer clicks along a serrated edge, so the lever can lock in any one of 25 positions.
[1] Survey of vehicle 251114, at Saumur, by Jean-Charles Breucque
[2] DW to Tiger 1
[3] Survey of Sturmtiger at Panzermuseum Munster, by Rob Veenendaal
[4] Der Panzerkampfwagen VI und seine abarten, Walter J. Spielberger, Motor Buch Verlag
[5] Survey of vehicle at Snegiri, by Anton Aleksandrovich