TM 1-1500-204-23-3 WARNING Drycleaning  solvent  is  flammable and solvent vapors are toxic.  Use P-D-680, Type II Solvent in a well- ventilated  area.    Keep  away  from open   flames.      Avoid   prolonged solvent contact with skin. 1 Screen-type.   The screen- type,   as   shown   in   figure   3-6,   with   its   double-walled construction, provides a large filtering area in a compact unit.    As  oil  passes  through  the  fine-mesh  screen,  dirt, sediment,  and  other  foreign  matter  are  removed  and settle to the bottom of the housing.  At regular intervals, the   cover   is   removed   and   the   screen   and   housing cleaned with a drycleaning solvent, P-D-680, Type II. 2 Cuno-type.    The  Cuno  oil filter  has  a  cartridge  made  of  disks  and  spacers.    A cleaner   blade   fits   between   each   pair   of   disks.      The cleaner blades are stationary, but the disks rotate when the   shaft   is   turned.      Oil   from   the   pump   enters   the cartridge  well  that  surrounds  the  cartridge  and  passes through the spaces between the closely spaced disks of the cartridge, then through the hollow center, and on to the engine.  Any foreign particles in the oil are deposited on   the   outer   surface   of   the   cartridge.      When   the cartridge is rotated, the cleaner blades comb the foreign matter  from  the  disks.    The  cartridge  of  the  manually- operated  Cuno  filter  is  turned  by  an  external  handle. Automatic Cuno filters have a hydraulic motor build into the   filter   head.      This   motor,   operated   by   engine   oil pressure,  rotates  the  cartridge  whenever  the  engine  is running.  There is a manual turning nut on the automatic Cuno   filter   for   rotating   the   cartridge   manually   during inspections. 3 Air-maze-type.      The   Air- maze   filter   contains   a   series   of   round,   fine-meshed screens  mounted  on  a  hollow  shaft.    The  oil  from  the pump  enters  the  well,  surrounds  the  screens,  and  then passes  through  them  and  the  shaft  before  entering  the engine.  The carbon deposits that collect on the screens actually improve their filtering efficiency. (b) Turbine   engines.      Filters   are   an important   part   of   the   lubrication   system,   since   they remove foreign particles that may be in the oil.  This is particularly   important   in   gas   turbines,   as   very   high engine speeds are attained, and the antifriction types of ball  and  roller  bearings  would  become  damaged  quite rapidly  if  lubricated  with  contaminated  oil.    Also,  there are usually a number of drilled or core passages leading to various points of lubrication Since these passages are usually   rather   small,   they   are   easily   clogged.      The spacers and screens and main oil strainer are explained in the following paragraphs. 1 Spacers and screens. This filter, as shown in figure 3-7, is made up of a stack of metal disks covered with a screen and separated by spacers so that the oil can flow through the screens and out the outlet port of the strainer body. Figure 3-6.  Oil Filter 3-9