Although the lubricant proposed by the invention is ideally for use under maximum temperatures of up to 200-250°C, it is to be appreciated that the lubricant may be used under a variety of different operating conditions.

The known all-purpose grease"Litol-24"is based on naphthenic oil mixtures thickened with a 12- hydroxystearic acid lithium soap. The grease has the following composition (GOST 21150-75), %: Thickener-12-hydroxystearic acid lithium soap-13 Additives-antioxidant-diphenylamine-0.5 or Neozone-phenylnapthylamine-0. 7 -viscosity-polyisobutylene-4 Dispersion medium-mixture of axle and industrial oils (1: 3) or residual distillate oils from Western Siberian petrololeum-up to 100 The grease has satisfactory anti-scuffing properties, but in many instances it is insufficient for normal plant operation.

The nearest to the proposed grease is grease for heavily loaded rolling-element and slide friction assemblies (Ukrainian patent No. 12341 A, 1996), having the following composition, % by mass: Graphite-6-20 Molybdenum disulphide-3-9 Organophosphoric additive-0.5-5 Soap thickened oils-63-91.5 Fatty acid-based alkyl phosphates are used as additives. The grease is prepared by mixing the constituents at high temperature.

However, the grease does not ensure the reliable operation of friction assemblies on which heavy loads and high temperatures act simultaneously, since many of its characteristics are unsuited to such operating conditions.

The aim of the invention is to produce such a middle-temperature grease for heavily loaded friction assemblies based on soap oils, introducing a new organophosphoric additive into its composition and thereby improving its operating characteristics, such as anti-wear and anti-scuff properties, as applied to the severe operating conditions of various friction assemblies, as well as extending the retention time of the grease on a surface.

The problem is resolved by a grease based on soap-thickened oils, containing an organophosphoric additive, and graphite and/or molybdenum disulphide characterised in that the organophosphoric additive essentially comprises a mixture of isomers being the product of the interaction between diethyl phosphite and N-arylsulphonylquinonimine.

The soap thickened oils are preferably a mixture of Ca-stearate or Li-12-hydroxystearate with heavy petroleum oils (MC20 oil).

The preferable composition of the grease in % by mass is as follows:: Ca-stearate or Li-hydroxystearate-8-20 Graphite-10-18 Molybdenum disulphide-5-8 Product of the interaction between diethyl phosphite and N-arylsulphonylquinonimine-1-3 Heavy petroleum oils (MC20 oil)-up to 100 The Ca-stearate or Li-12-hydroxystearate form part of the grease as thickeners, but when their content is under 8% by mass the grease becomes liquid and is not retained in an open friction assembly; whereas when the content is over 20% the grease's internal friction with the surface rises, which is undesirable in the operation of bearings, since it leads to a deterioration in the adhesive properties of the grease and an increase in energy consumption.

Using heavy petroleum oils as the base, the upper temperature limit for the working efficiency of the grease is raised to 150-180°C, and in conjunction with fillers-graphite and molybdenum disulphide-up to 200°C and possibly greater.

The organophosphoric additive comprises a mixture of isomers, obtained through the interaction of diethyl phosphite and N-arylsulphonylquinonimine according to the reaction: The additive is obtained by the following method: 1 mole of arylsulphonylquinonimine is added to 1.25 mole of diethyl phosphite while mixing at a temperature of 125°C in batches. The mixture is allowed to stand for four hours at a temperature of 105°C, from which the mixture of isomers of formula (1) is obtained.

The additive was tested using friction machines at critical loads by a method of comparing with industrial oils as a reference standard.

An experiment was conducted until the destruction of the test-pieces as a result of seizure of the friction surfaces. Table 1 shows the relationship of the grease characteristics to the load on the friction assembly.

Table 1 Load (kgf/cm2) 10 15 20 25 30-35 40 45 50 Clean industrial 8. 42 9. 94 11. 76 15. 25 20.55 24.34-- oil (kg cm) 1% Additive 8. 38 10. 3 12. 4 15. 75 20.34 23.6 28. 38- 2% Additive 8.46 10.65 12.85 16.12 20.41 23.3623.36 27.87 32.61 1 3% Additive 8. 44 11. 01 13. 6 16. 8 20.25 32.58 4% Additive 8. 41 11. 61 14. 49 17. 52 20.58 23.28 27.37 32.53 The use of the proposed additive increases the load under which the destruction of the test-pieces takes place. It can be seen from table 1 that on introducing a quantity of 1 % additive into the oil, the friction assembly? s critical load rises by 15%, and on increasing the additive concentration up to 4%, the critical load rises by 30%. The grease is prepared by mixing while heating up to 100°C. The data on the composition of the grease are given in table 2.

Table 2 Grease Contents of constituents, by % mass constituents: sample 1 sample 2 sample 3 sample 4 1. Ca-stearate 20 15-- 2. Li-12-hydroxystearate 8 12 3. Graphite 10 16 18 16 4. Mo disulphide 5 6 8 6 5. 1322 6. MC20 oil up to 100 up to 100 ut to 100 up to 100 Table 3 gives the physico-chemical properties of the suggested and known greases: dropping point temperature, penetration, colloidal stability.

Table 3 Description of grease compositions property 1 2 3 4 prototype Penetration 25°C 250 300 240 260 210 Dropping point temperature °C 190 210 195 220 180 Colloidal stability, % of separated oil 11 9 12 8 12 It can be seen from table 3 that the grease composition samples 1-4 with respect to the prototype relate to a single class of lubricating grease according to rheological characteristics (similar penetration properties), whilst according to working characteristics they are far superior to the prototype grease. As a higher dropping point characterizes the thermal stability of the grease-it is higher than the known one-the colloidal stability of the proposed grease is also 1-1.5 times higher.

Grease prepared according to the procedure described above, was tested at the Novolipetsk metallurgical plant in a sheet rolling mill on the output roller conveyor of the"2000"mill's continuous furnaces. The grease was placed in assemblies that had been washed with kerosene and air-blown, disconnected from the centralized grease supply. The tests showed that under conditions of high temperature (300-350°C), ingress of water and slag, the assemblies operated without attention for 200 twenty-four-hour periods. Similar assemblies, operating on known greases (in particular, on IP-1 greases of the firm"Mobil plex", required grease being pumped by the centralized systems at hourly intervals. After opening up the bearings of the assemblies, it was found that after 200 twenty-four-hour periods of continuous operation the quality of the grease had not altered, the quantity of grease remained as before, and on examining the bearings no defects were detected.