Power Steering Gear Fluids

As a base for such a fluids, a solvent refined oil of about 250 viscosity SUS at 100 degree F may be used. While , as Johnson and Mortensen state, the major requirements are shear  stability  and high  V.I., the oil should  also  be  resistant  to oxidation and  have no  adverse effects on both metals  and  seal and  hose  materials. Likewise the blended oil should have a low pour point. All of the above point to a solvent refined oil which will have the desired high V.I. and aniline number.

Chrysler MS 3590 “Hydraulic Steering Fluid with Rust Preventive”, summarizes the composition requirements as follows:

“Well refined oil with admixture of proper rust preventive additives. Small amounts of oxidation inhibitor and pour depressant may also be used to meet the details requirements. The use of   detergents and V.I. improvers is prohibited. The additives small be selected to have a minimum effect on the seal and hose materials”.

Therefore, additives may  include up to 0.5 per cent  of an  oxidation inhibitor, such as  can be  recommended  by  an  additive supplier, or  may  be  phenyl  alpha napththylamine , 2,6-ditertbutyl – 4- methyl  phenol, mixtures  of these  two  types, or  an oil-soluble  organic thiophosphate salt of certain  metals, such  as zinc  methylphenyl  dithiophosphate.

If the pour point of the oil is above -20 degree F, from 0.2 to 1 per cent of a pour depressant, such as “Acryloid  150”, “Paraflow”, or “ Santopour C”, can be added.

Suitable rust inhibitors, used in concentrations of 0.5 to 2 per cent, include petroleum or synthetic sulfonates, such as “Petronate” or barium dinonyl naphthalene sulfonate. A combination oxidation and rust inhibitor, which is usually used in a concentration of 1 per cent or less, is “Vanlube 76”. 

Inboard Marine Engines and Transmissions gear lubrication

Where  inboard  engines,  either  gasoline  or diesel, are  used to  drive pleasure  craft  or  small  commercial  boats, there  will  be  a wide  variance in the  lubricants used in the  transmissions. This is due to design differences. Therefore, the  lubricating fluid recommended  may  be an  EP gear  oil  or a  straight  mineral  oil  falling within the SAE  90, 140 or 250 viscosity  range, a motor oil, or an  automatic transmission fluid. The  lubricant for the  reduction gears may be  supplied  under  pressure  from the engine oil  system or an independent  oil  system  for the  gears  alone  may be provided. The  lubricant then  will  no  doubt  be an  SAE 50  oil  for summer  and an  SAE 30  or 40 for  winter operation. With separate  lubricating  system  for the  gears, the  corresponding oils may be an  SAE  140  or  SAE  90.

The  fluid  used  in a  hydraulically  shifted transmission must serve as a  hydraulic  medium  for a  complex  control  system and also  act as a  lubricant and heat  transfer medium. This, then points to the use  of ATF. In addition to the transmission, which provides for reversing, neutral, and forward speed, in large boats, a further reduction gear unit may be found. It may even be that the former gears may be lubricated from the engine and the latter require the heavy gear oil.

Due to the variations in drives and methods of lubrication, the supplier of the engine is in the best position to recommend the proper lubricant for gear trains.  

Hydraulic Transmission Fluid, Type C-1

In 1995 Allison  Division  of  GMC  provided a  specification  for a  fluid  for  use  in  heavy  duty  truck, bus  and  earth  moving  vehicle  hydraulic  transmission, which  they  manufactured. In  these  application, Type  A  and Type A, Suffix A,  ATF  products,  described  later, showed  exceptionally  satisfactory   performance. However, the service in question did not demand all of the characteristics   of ATF. Therefore, by reducing the requirements of the fluid, less costly ingredients could be used.

The Allison specification was designated Hydraulic Transmission Fluid, Type C. Many heavy duty motor oils in the SAE 10W, SAE 20, and 20W viscosity classes in addition to some special fluids, adequately met the specification. Subsequent service showed that fluids in the SAE 10W class were most desirable. Consequently the specification was modified and updated as of 1997. A designation Hydraulic Fluid Type C-1 was   assigned to the new product. It  will  be  found  that other  manufacturers also  recommend  fluids of this type  for their  heavy  duty  torque  converters. 

Introduction

Almost  all  modern  machinery  makes  some  use  of  gears  as  a  medium  for  transmitting  power. Such use  may  be  for  the  purpose  of  either  changing  the  speed  of  a  driven  member  or  changing  the  direction  of  movement. In  either  case  the  gears  act as a lever  so  that , in  most  cases, the  force  transmitted  is  multiplied  and  in  so  doing  speed  will  be  reduced. When  variations  in  the  torque  or  speed  transmitted  are  desired, a  series  of  gear  ratios  can  be  provided  in  the  same  mechanism.

Most  gear  sets  are  lubricated  with  fluid  products  or  gear  oils, and  consequently, such  compounds  will  receive  major  consideration . Since  plastic  or  semi-fluid  products, such  as  lubricating  greases, as  well  as  solids  are  sometimes  used  as  gear  lubricants, they  will  also  receive  mention.

It  is  also  the  purpose  to  describe  fluids  employed  in  certain  fluid  drives, particularly  automatic  transmissions  in  automotive  vehicles. Here  the  oils  in  question  serve  a  number  of  functions, and  it  is  necessary  that  a  single  fluid  satisfy  not  only  lubrication  of  different  mechanisms, but  also  act  as  a  torque  converter  and  hydraulic  agent.

This  is  simply  an  extension  of  the  functions  which  gear  oils  fill  in  many  case. Thus, gear lubricants   also take care of bearing lubrication in many   applications. It will  be  presumed  that  most  readers  are familiar  with  the  mechanisms  to  be  lubricated, such  as  automatic  transmissions, hypoid  gears, worm  gears, etc. Therefore, little description of mechanical details will be attempted.

The  primary  interest  will  be  in  lubricants  for  metal  gears, although  mention  will  be  made  of  the  requirements  for  gears  made  from  other  materials. An  attempt  will  be  made  to  thoroughly   explain  how  lubricants  for  gears  function, what  they  contain, how  they   are  compounded, and  the  limitations  of  their  use. In  all  of  this  it  should  be  kept   in  mind  that  to  be  most  effective   any  lubricant  should  be  applied  in  the  right  amount  at  the  right  place  and  the  right  time.

Fundamentally  the   types   of  motion  in  operating  gear  sets  are  those  occurring  in  other  machine  elements , namely, rolling  and  sliding  motion. The two types of movement   may occur simultaneously as in meshing   hypoid gears. This  is  pointed  out  so  that  it  will  be  realized  that, even  though  the  configuration  of  gears  differ   from  bearings, the  lubricating  problems  are similar  for  both  mechanisms. Another  point  to  keep  in  mind  is  that  while  the  title  of  the  mentions  both  gear  and  transmission  lubrication, the latter  mechanism  is  most  often  one  or   more  gear  sets  serving  a specific  purpose. Therefore, except  in  the  case  of  fluid  drives, the  problem  is  one  of  gear  lubrication. Finally , some of  the  possibilities  of  future  trends  and  developments  in  gear  lubricants  and  torque  fluids  will  be  mentioned.