Technology and Operations
This forum is for discussing technological & operational matters pertaining to U-boats.
RE: U-Boat Propulsion
Posted by:
Rainer Bruns
()
Date: July 21, 2000 02:31PM
Hi Robert,
I am not sure that I fully understand your question in view of your phrase 'on one side' and 'on the other side'. Let me try to explain it as follows:
First: Both propulsion systems (port and starboard) were set up identically. From forward to aft end machinery was set up in the following way:
Diesel engine==>Short Shaft==>Electric Motor==>Main Clutch==>Shaft with Main Thrust Bearing==>Shaft inside Stern Shaft Seal==>Shaft outside and screw support by strut bearing.In addition the shaft could be mechanically decoupled at the aft end of the Diesel.
Thus under normal operation the Diesel would be turning the E-motor (switched to and functioning as a generator charging batteries) and turning shaft and screw. Once batts are full, Diesel can be declutched, E-motors switched from generator charging mode to propulsion (drawing juice from batts) etc.
Since everything is duplicated on both P&S, you can see that the engineer could stop one Diesel, switch it's E-motor to pro=
pulsion (drawing juice from the other E-motor in generator mode), and do routine maintenance or emergency repairs on the Diesel with both screws turning. So you can see, there are a couple of options how to get on.
In addition you could stop one side completely and proceed with Diesel or electrically with the other. This happened on U175, when homebound off West Africa she got a pasting from aircraft DC causing an uncontrolled dive down to 310 meters and severe damage. Among other damage, the shaft strut and bearing just foreward of the screw broke off, leaving the tail end of the shaft assembly unsupported. They made it home to Lorient on one shaft using the other diesel for charging only.
You are correct that there is a sideways slewing under one shaft propulsion. This is easily corrected by applying a couple degrees of counter rudder. This has no ill effects on the rudder shaft ansd bearings as they are designed for full hardover turns
at max. speed. Obviously, it is a bitch to steer in any kind of sea; and maneuvering at close quarters you might as well call a tug.
Hope this was helpful, RB
I am not sure that I fully understand your question in view of your phrase 'on one side' and 'on the other side'. Let me try to explain it as follows:
First: Both propulsion systems (port and starboard) were set up identically. From forward to aft end machinery was set up in the following way:
Diesel engine==>Short Shaft==>Electric Motor==>Main Clutch==>Shaft with Main Thrust Bearing==>Shaft inside Stern Shaft Seal==>Shaft outside and screw support by strut bearing.In addition the shaft could be mechanically decoupled at the aft end of the Diesel.
Thus under normal operation the Diesel would be turning the E-motor (switched to and functioning as a generator charging batteries) and turning shaft and screw. Once batts are full, Diesel can be declutched, E-motors switched from generator charging mode to propulsion (drawing juice from batts) etc.
Since everything is duplicated on both P&S, you can see that the engineer could stop one Diesel, switch it's E-motor to pro=
pulsion (drawing juice from the other E-motor in generator mode), and do routine maintenance or emergency repairs on the Diesel with both screws turning. So you can see, there are a couple of options how to get on.
In addition you could stop one side completely and proceed with Diesel or electrically with the other. This happened on U175, when homebound off West Africa she got a pasting from aircraft DC causing an uncontrolled dive down to 310 meters and severe damage. Among other damage, the shaft strut and bearing just foreward of the screw broke off, leaving the tail end of the shaft assembly unsupported. They made it home to Lorient on one shaft using the other diesel for charging only.
You are correct that there is a sideways slewing under one shaft propulsion. This is easily corrected by applying a couple degrees of counter rudder. This has no ill effects on the rudder shaft ansd bearings as they are designed for full hardover turns
at max. speed. Obviously, it is a bitch to steer in any kind of sea; and maneuvering at close quarters you might as well call a tug.
Hope this was helpful, RB
