Provided are a lubricating oil composition containing a base oil, a specific thiophosphate compound (A) and a molybdenum-based compound (B), which exhibits excellent wear resistance and has a low friction coefficient in a broad range of contact pressures ranging from high to low; and a precision reduction gear using the lubricating oil composition.

Provided are a lubricating oil composition containing a base oil and a specific thiophosphate compound (A) and not substantially containing a molybdenum-based, and a precision reduction gear using the lubricating oil composition. The lubricating oil composition and the precision reduction gear using it exhibit excellent wear resistance and can prevent sludge generation in a broad range of contact pressures ranging from high to low.

The present invention concerns a friction piece (10) suitable for operating in a lubricated medium at a temperature higher than 200 C. The piece (10) comprises a metal surface (12) and an external coating (14) composed of tungsten carbide doped with nitrogen WC(N) with an atomic ratio of nitrogen between 5 and 12%. The invention also relates to a mechanical system (1) comprising such a piece (10). The invention also relates to a method for implementing such a piece (10).

A lubricating oil composition for a sliding guide surface, which includes a lubricant base oil, an acid phosphate ester mixture having a structure represented by the following Formula (1) and including an acid phosphate monoester and an acid phosphate diester, and an aliphatic monoamine, and which satisfies a predetermined condition A or condition B, is provided. In Formula (1), each of R.sup.1 and R.sup.2 represents a hydrogen atom or a saturated or unsaturated straight-chain aliphatic hydrocarbon group having from 1 to 30 carbon atoms, and R.sup.1 and R.sup.2 are not simultaneously hydrogen atoms.

(R.sup.1O)(R.sup.2O)(HO)PO(1)

Provided are a lubricating oil composition containing a base oil, a specific thiophosphate compound (A) and a molybdenum-based compound (B), which exhibits excellent wear resistance and has a low friction coefficient in a broad range of contact pressures ranging from high to low; and a precision reduction gear using the lubricating oil composition.

Provided are a lubricating oil composition containing a base oil and a specific thiophosphate compound (A) and not substantially containing a molybdenum-based, and a precision reduction gear using the lubricating oil composition. The lubricating oil composition and the precision reduction gear using it exhibit excellent wear resistance and can prevent sludge generation in a broad range of contact pressures ranging from high to low.

The present invention relates to lubricant compositions for motorcycle engines where the crankcase lubricant is also used to lubricate a wet clutch. The lubricant compositions contain antimony dithiocarbamates in combination with one or more ash-free friction modifiers.

An internal combustion engine crankcase lubricating oil composition having a sulphated ash content of no greater than 1.2 mass %, based on the mass of the lubricating oil composition, and a phosphorous content of no greater than 0.1 mass %, based on the mass of the lubricating oil composition, which lubricating oil composition comprises or is made by admixing: (A) a crankcase base oil of lubricating viscosity, in a major amount; and (B) the following additives, in respective minor amounts: (B1) a polymeric friction modifier being the reaction product of (a) a functionalized polyolefin, (b) a polyether, (c) a polyol, and (d) a monocarboxylic acid chain terminating group; and (B2) at least one oil-soluble molybdenum compound.

An internal combustion engine crankcase lubricating oil composition having a sulphated ash content of no greater than 1.2 mass %, based on the mass of the lubricating oil composition, and a phosphorous content of no greater than 0.1 mass %, based on the mass of the lubricating oil composition, which lubricating oil composition comprises or is made by admixing: (A) a crankcase base oil of lubricating viscosity, in a major amount; and (B) the following additives, in respective minor amounts: (B1) a polymeric friction modifier being the reaction product of (a) a functionalized polyolefin, (b) a polyether, (c) a polyol, and (d) a monocarboxylic acid chain terminating group; and (B2) at least one oil-soluble molybdenum compound.

Disclosed is a lubricating oil composition containing a base oil, a viscosity index improver, a molybdenum-based friction modifier, a boron-containing dispersant, and at least two extreme-pressure additives selected from a sulfur-based extreme-pressure additive, a phosphorous-based extreme-pressure additive and a sulfur/phosphorus-based extreme-pressure additive, or a sulfur/phosphorus-based extreme-pressure additive. The base oil is a synthetic oil having a kinematic viscosity at 100 C. of 3 mm.sup.2/s or more and 10 mm.sup.2/s or less, the viscosity index improver is a resin having a number average molecular weight (Mn) of 1,000 or more and 10,000 or less, the mass ratio of boron atoms (B) contained in the boron-containing dispersant to molybdenum atoms (Mo) contained in the molybdenum-based friction modifier, [(B)/(Mo)] is 1 or more and 5 or less, and the mass ratio of sulfur atoms (S) to phosphorus atoms (P) contained in the extreme-pressure additive(s), [(S)/(P)] is 10 or more and 20 or less.