STANDARD LUBRICATING OIL SYSTEM FOR GEARED TURBINES. 265 



I will give a brief outline of the two types or systems which were developed by our 

 department for this work. The pressure system developed is composed of two pumps, con- 

 trolled by pump governors of the diaphragm type. These pumps discharge into a supply 

 pipe or header which supplies the oil directly to the bearings and gear teeth, having first 

 passed through suitable strainers, etc. Having passed through the bearings and gears, it 

 drains back into a drain tanl<, from which it is sucked up by the pumps and discharged 

 back into the system. The pressure is maintained by tlie operation of a pump governor, 

 which causes the pressure to be constant, regardless of any differences of steam pressure or 

 resistances on the oil side, which is considered an essential feature. 



In addition to the automatic control of the pressure we provided a safety alarm — a me- 

 chanical device — by means of which a small whistle is blown in case the oil pressure should 

 go down below what was considered a safe limit. In addition to this, we also provided a 

 positive safety-stop device for the turbine itself. In case the pressure goes down to about 

 half of the working pressure, this device will shut the steam off from the turbine and actu- 

 ally cause the turbine to stop. 



The gravity system which we developed was somewhat different from the system de- 

 scribed in this paper, in that the pumps were controlled by a float in the drain tank, so that 

 they automatically keep the oil pumped up into the gravity tank, and in this way they re- 

 quired no attention at all from the engineer. The automatic control of the pump, I think, 

 is quite an important feature, because without it the engineer is likely to fail to regulate the 

 speed of the pump correctly. In spite of some of the safety devices which were adopted, 

 one of the ships which we turned out was broken down, due to the fact that the gravity 

 tank ran dry, the bearings having burned out. 



In comparing the two types, the pressure system is considerably simpler and cheaper 

 and requires less piping. The piping is smaller and requires fewer tanks. The pressure is 

 also more positive and is more under the control of the operator. If any condition occurs 

 requiring more pressure, he can adjust his pump governor and get what he wants. 



In the case of the gravity system, the maximum pressure is fixed by the designer, but 

 in some cases, through improper pipe design or some fault of design in the bearings, etc., 

 it is desired to get a higher pressure than the system provides for, which cannot be done. 

 This is also true where a very heavy oil is used and the temperatui-e is low. This increases 

 the viscosity and the friction of the oil in the pipes, which cuts down the pressure at the 

 bearings. I saw quite a serious accident occur from this cause. 



The pressure system has certain advantages in that it does not require such close de- 

 signing, and you can carry a pressure of 10 or 15 pounds, which is more than you actually 

 need at your bearings. In other words, you provide a large margin of safety in the case 

 of your pressure, and, in my opinion, that is an advantage for the pressure system which 

 should be considered. 



The difficulties which have been experienced with lubricating oil systems have been 

 pointed out in this paper in several places. From my observation, these difficulties were 

 due mainly to faulty installation and partially to faulty operation. In the pressure systems 

 where these troubles occurred, they were nearly always in systems where the pressure was 

 not automatically regulated. If, after the pump speed has been adjusted, the steam pres- 

 sure should go down, it will cause the oil pressure to go down, and in some cases it has 

 caused the pumps to slow down to such an extent that the oil pressure has failed and the 

 bearings have burned out. Had this installation been provided with the proper automatic 

 regulation, this accident would not have occurred. 



