Technology and Operations
This forum is for discussing technological & operational matters pertaining to U-boats.
RE: U-Boat Propulsion
Posted by:
Don Baker
()
Date: July 23, 2000 07:05PM
Hi Robert
Rainer has done a good job of describing the diesel-electric drive systyem used on the u-boats. The ability to clutch and de-clutch both the diesel and electric motors from the propellor shaft was used to good advantage in a critical phase of the salvage of U-505 in preparing her for the tow across the Atlantic.
To follow what happened it is necessary to understand the electric drive motors also functioned as the generators while charging batteries. To make the motor act as a generator was simply the act of setting some switches on the control panel. In the normal course of things, when it became necessary to charge batteries, the diesel engine was cutched to the electric motor shaft which was in turn clutched to the propellor shaft. In this arrangement the diesel engine turned the electric motor shaft with the motor now "wired up" to generate, and the electric motor shaft turned the propeller shaft driving the submarine. The thing to remember is that the electric drive motor when acting as a generator really doesn't care what is turning its shaft - it is only necessary that the generator shaft be turned in order to generate electricity.
U-505 was badly in need of pumping out in order to restablish full surface trim. The bilge pumps were electric and drew power from the battery. However the battery was discharged and could not provide sufficient electrical current to run the pumps. So Guadalcanal's engineering officer and his men rigged things so that the generators could charge the battery without running the diesel engines. The diesels were de-clutched from the electrical motors but the electric motors were left clutched to the propellor shafts. The appropriate switches were set by the electricians and Guadalcanal then towed U-505 all night at 14 Kts. The "windmilling" propellors then spun the propellor shafts which in turn spun the generator shafts. The generators then pumped current into the batteries. The next morning there was enough charge in the batteries to run the bilge pumps.
It was the clutching system between the diesels, the electric motors, and the propellor shafts which made all this possible.
Don B
Rainer has done a good job of describing the diesel-electric drive systyem used on the u-boats. The ability to clutch and de-clutch both the diesel and electric motors from the propellor shaft was used to good advantage in a critical phase of the salvage of U-505 in preparing her for the tow across the Atlantic.
To follow what happened it is necessary to understand the electric drive motors also functioned as the generators while charging batteries. To make the motor act as a generator was simply the act of setting some switches on the control panel. In the normal course of things, when it became necessary to charge batteries, the diesel engine was cutched to the electric motor shaft which was in turn clutched to the propellor shaft. In this arrangement the diesel engine turned the electric motor shaft with the motor now "wired up" to generate, and the electric motor shaft turned the propeller shaft driving the submarine. The thing to remember is that the electric drive motor when acting as a generator really doesn't care what is turning its shaft - it is only necessary that the generator shaft be turned in order to generate electricity.
U-505 was badly in need of pumping out in order to restablish full surface trim. The bilge pumps were electric and drew power from the battery. However the battery was discharged and could not provide sufficient electrical current to run the pumps. So Guadalcanal's engineering officer and his men rigged things so that the generators could charge the battery without running the diesel engines. The diesels were de-clutched from the electrical motors but the electric motors were left clutched to the propellor shafts. The appropriate switches were set by the electricians and Guadalcanal then towed U-505 all night at 14 Kts. The "windmilling" propellors then spun the propellor shafts which in turn spun the generator shafts. The generators then pumped current into the batteries. The next morning there was enough charge in the batteries to run the bilge pumps.
It was the clutching system between the diesels, the electric motors, and the propellor shafts which made all this possible.
Don B
