Special oil composition for gearbox of rail traffic vehicle as well as preparation method and application of special oil composition

Abstract

The invention belongs to the technical field of lubricating oil, and particularly relates to a special oil composition for a gearbox of a rail transit vehicle as well as a preparation method and application thereof. The special oil composition for the gear box of the rail transit vehicle comprises the following components: a friction modifier shown in a formula (1), a solubilizer, an extreme pressure anti-wear agent, a dispersing agent, a metal deactivator, an anti-foaming agent and base oil, wherein R1 and R2 in the formula (1) are independently selected from C4-C18 straight-chain or branched-chain alkyl groups. According to the special oil composition for the gear box of the rail transit vehicle, a protective film can be rapidly formed on the surface of a friction pair by using the friction modifier shown in the formula (1), and gear and bearing abrasion caused by insufficient oil supply is prevented. The composition is excellent in performance, has a good antifriction effect, avoids the conditions of overhigh temperature rise, gearbox shaft temperature alarm and bearing sintering caused by higher rotating speed of driving teeth in a gearbox, oil stirring loss of lubricating oil and overhigh mechanical energy loss of a friction surface, and has a good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of lubricating oil technology, specifically relating to a special oil composition for rail transit vehicle gearboxes, its preparation method, and its application. Background Technology

[0002] Currently, there is no unified standard for gearbox oil in rail transit locomotives and rolling stock. Gearbox manufacturers generally require additional specific bench tests based on API GL-5 heavy-duty vehicle gear oil or SAE J2306 specifications. While API GL-5 and SAE J2306 specifications do not specify oil friction-reducing properties, rail transit locomotive and rolling stock gearboxes operate at high speeds. The gear oil needs to lubricate both the internal traction gears and bearings. Insufficient oil friction-reducing properties lead to significant losses in gear meshing, bearing friction, and churning power, resulting in abnormally high gearbox oil temperatures. Excessive temperatures can cause bearing sintering and damage, seriously threatening the operational safety of locomotives and rolling stock. In some locomotives and rolling stock equipped with temperature sensors, an alarm is triggered if the axle temperature exceeds 125°C, causing emergency braking and affecting the safe operation of the entire line.

[0003] Chinese invention patent publication number CN118146859A discloses a locomotive gearbox lubricating oil composition and its preparation method. The composition comprises the following components by weight percentage: 86.00-97.78 wt% base oil, 2.0-12.0 wt% gear oil composite additive, 0.2-1.0 wt% friction surface self-repairing additive, and 0.02-1.0 wt% extreme pressure anti-wear reinforcing additive. The sum of the weight percentages of the above components is 100%. The invention also discloses a method for preparing the locomotive gearbox lubricating oil composition, which involves adding the above components in proportion to a mixing vessel and stirring the mixture to obtain the final product.

[0004] Another Chinese invention patent publication number CN115029174A discloses a long-life energy-saving gearbox oil and its preparation method. The gearbox oil includes liquid A and liquid B, which contain the following components in the indicated weight ratios: liquid A contains 60% 650BS base oil, 20% 250BS base oil, and 20% 150BS base oil; liquid B contains 1.5% high-alkalinity synthetic calcium sulfate T106, 0.5% alkyl salicylate calcium T109, 1% monoalkenyl succinimide T151, 1% diene succinimide T152, 0.1% polyalphaolefin T803, 0.8% alkenyl succinic acid T746, 0.5% 0.50 μL / L methyl silicone oil T901, and 0.5% 2,6-di-tert-butyl-p-cresol T501.

[0005] Another Chinese invention patent publication, CN112625778A, discloses a special oil composition for urban rail gearboxes with a viscosity grade of 75W-90. This gearbox oil composition comprises the following components in parts by weight: 50-70 parts synthetic base oil, 10-30 parts viscosity index improver, 3-10 parts extreme pressure agent composition, 0.1-0.14 parts metal deactivator, 2-4 parts detergent-dispersant, 0.15-0.25 parts antioxidant, 0.2-0.4 parts demulsifier, and 0.03-0.07 parts non-silicone antifoaming agent; the extreme pressure agent composition includes 0.4-0.6 parts extreme pressure anti-wear agent, 4-7 parts sulfur-containing extreme pressure agent, and 2-4 parts phosphorus-containing anti-wear agent.

[0006] However, the gearbox-specific oil compositions prepared by the above invention all use conventional extreme pressure anti-wear agents, resulting in generally poor friction reduction performance, which cannot meet the friction reduction performance requirements for safe operation of locomotive and rolling stock gearboxes.

[0007] Therefore, there is an urgent need in the field to provide a special oil composition for rail locomotive gearboxes that has excellent friction-reducing properties and effective temperature rise control. Summary of the Invention

[0008] This invention addresses the problems existing in the prior art by providing a special oil composition for rail transit vehicle gearboxes, its preparation method, and its application.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] A special oil composition for rail transit vehicle gearboxes comprises the following components: friction modifier, solubilizer, extreme pressure anti-wear agent, dispersant, metal passivator, antifoaming agent, and base oil, wherein the chemical structure of the friction modifier is shown in formula (1):

[0011]

[0012] In formula (1), R1 and R2 are each independently selected from straight-chain or branched alkyl groups of C4-C18.

[0013] Preferably, the solubilizer is selected from those with a kinematic viscosity of 10 mmHg at 100°C. 2 Synthetic esters with a density of less than 1 / s can improve the additive solubility of base oils and enhance the rubber compatibility of polyalphaolefins.

[0014] More preferably, the solubilizer is selected from one or more of pentaerythritol ester, dipentaerythritol ester, trimethylolpropane ester, and diisotridecyl adipate.

[0015] Preferably, the extreme pressure anti-wear agent is selected from one or more of isobutylene sulfide, polysulfides, sulfur-phosphorus-nitrogen compounds, di-n-butyl phosphite, alkyl phosphate amine salts, tricresyl phosphate, and triphenyl thiophosphate.

[0016] Preferably, the polysulfide is a di-tert-octyl polysulfide, a di-tert-nonyl polysulfide, or a di-tert-dodecyl polysulfide.

[0017] Preferably, the sulfur, phosphorus, and nitrogen compound is octadecyl dithiophosphate, dioctyl dithiophosphate, or didecyl dithiophosphate.

[0018] Preferably, the alkyl phosphate amine salt is a di(dodecyl) phosphate (diisooctylamine) salt, a diisooctyl phosphate (ditridecylamine) salt, or a di(isotridecyl) phosphate tert-alkyl primary amine salt.

[0019] Preferably, the dispersant is selected from one or more of polyisobutylene succinimide, boronized polyisobutylene succinimide, and phosphobically boronized polyisobutylene succinimide.

[0020] Preferably, the metal passivating agent is selected from one or both of benzotriazole derivatives and thiadiazole derivatives.

[0021] Preferably, the benzotriazole derivative is a methylbenzotriazole di-n-butylamine Mannich condensate, a methylbenzotriazole di-n-octylamine Mannich condensate, or a methylbenzotriazole di(tetrazine) Mannich condensate.

[0022] Preferably, the thiadiazole derivative is 2,5-bis(tert-nonyldithio)-1,3,4-thiadiazole or 2,5-bis(tert-dodecyldithio)-1,3,4-thiadiazole.

[0023] Preferably, the antifoaming agent is selected from one or more of polymethylsiloxane, acrylate-ether copolymer and polyacrylate.

[0024] Preferably, the base oil is selected from oils with a kinematic viscosity of 4-200 mmHg at 100°C. 2 / s of polyalphaolefin. Polyalphaolefin, as a base oil, serves as both a viscosity modifier and a carrier, ensuring the uniform dispersion of various functional additives.

[0025] More preferably, the base oil is selected from one or more of PAO 4, PAO 6, PAO 10, PAO 20, PAO 40, PAO 100, mPAO65 and mPAO 150.

[0026] More preferably, the base oil is selected from one or two of PAO 4, PAO 6, PAO 10, PAO 20, PAO 40 and PAO 100.

[0027] Preferably, by weight percentage, it comprises the following components:

[0028]

[0029] The present invention also provides a method for preparing the above-mentioned special oil composition for rail transit vehicle gearboxes, comprising the following steps: mixing friction modifier, solubilizer, extreme pressure anti-wear agent, dispersant, metal passivator, antifoaming agent and base oil to obtain the final product.

[0030] The present invention also provides the application of the above-mentioned special oil composition for rail transit vehicle gearboxes or the special oil composition for rail transit vehicle gearboxes prepared by the above-mentioned preparation method in the preparation of special lubricating oil for rail transit vehicle gearboxes.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The special oil composition for rail transit vehicle gearboxes provided by the present invention can quickly form a protective film on the surface of the friction pair by using the friction modifier shown in formula (1), thereby preventing wear of gears and bearings due to insufficient oil supply.

[0033] (2) The special oil composition for rail transit vehicle gearboxes of the present invention uses fully synthetic polyα-olefin as base oil and ester oil as solubilizer, which has excellent low temperature performance, good fluidity under extremely cold conditions, and can be used in all seasons and regions.

[0034] (3) The special oil composition for rail transit vehicle gearboxes of the present invention has excellent performance and good friction reduction effect. It can effectively reduce the friction coefficient, control the temperature rise of gearbox gears and matching bearings, maintain the thermal balance inside the gearbox, and avoid excessive temperature rise caused by high speed of the active gear inside the gearbox, excessive oil churning loss and excessive mechanical energy loss of friction surface, resulting in gearbox shaft temperature alarm and bearing sintering. It has good application prospects. Attached Figure Description

[0035] Figure 1 The results are from the four-ball friction coefficient test. Detailed Implementation

[0036] It is worth noting that the raw materials used in this invention are all commercially available products.

[0037] Example 1

[0038] A special oil composition for rail transit vehicle gearboxes, the components and contents of which are shown in Table 1 by weight percentage.

[0039] Table 1. Composition and content of special oil composition for rail transit vehicle gearboxes

[0040] composition Content / wt% PAO 40 71.00 PAO 10 7.00 Pentaerythritol ester 13.50 Friction modifier 1.00 Isobutylene sulfide 3.34 Di(dodecyl)phosphate (diisooctylamine) salt 0.79 Polyisobutylene succinimide 3.15 methylbenzotriazole di-n-butylamine Mannich condensate 0.20 polymethylsiloxane 0.01 acrylate ether copolymer 0.01

[0041] Pentaerythritol ester: Kinematic viscosity at 40°C 28.17 mmHg 2 / s, kinematic viscosity at 100℃: 5.262mm 2 / s, acid value 0.01mgKOH / g, flash point 265℃, pour point -60℃;

[0042] Friction modifier: Its chemical structure is shown in formula (1), where R1 and R2 are both 2-ethylhexyl.

[0043]

[0044] The preparation method of the above-mentioned special oil composition for rail transit vehicle gearboxes is as follows: PAO 40, PAO 10, pentaerythritol ester, friction modifier, sulfurized isobutylene, di(dodecyl) phosphate (diisooctylamine) salt, polyisobutylene succinimide, methylbenzotriazole di-n-butylamine Mannich condensate, polymethylsiloxane and acrylate ether copolymer are placed in a high-speed mixer and stirred until homogeneous to obtain the final product.

[0045] Example 2

[0046] A special oil composition for rail transit vehicle gearboxes, the components and contents of which are shown in Table 2 by weight percentage.

[0047] Table 2. Composition and content of special oil composition for rail transit vehicle gearboxes

[0048] composition Content / wt% PAO 20 78.30 Diisotridecyl adipic acid ester 13.50 Friction modifier 0.70 ditert-nonyl polysulfide 3.34 Triphenyl thiophosphate 0.79 Boronized polyisobutylene succinimide 3.15 2,5-Bis(tert-nonyldithio)-1,3,4-thiadiazole 0.20 polymethylsiloxane 0.01 Polyacrylate 0.01

[0049] Friction modifier: Its chemical structure is shown in formula (1), where R1 and R2 are both n-dodecyl groups.

[0050]

[0051] The preparation method of the above-mentioned special oil composition for rail transit vehicle gearboxes is as follows: PAO 20, diisotridecyl adipate, friction modifier, di-tert-nonyl polysulfide, triphenyl thiophosphate, boronized polyisobutylene succinimide, 2,5-bis(tert-nonyldithio)-1,3,4-thiadiazole, polymethylsiloxane and polyacrylate are placed in a high-speed mixer and stirred until homogeneous to obtain the final product.

[0052] Example 3

[0053] A special oil composition for rail transit vehicle gearboxes, the components and contents of which are shown in Table 3 by weight percentage.

[0054] Table 3. Composition and content of special oil composition for rail transit vehicle gearboxes

[0055] composition Content / wt% PAO 100 37.00 PAO 4 41.00 Trimethylolpropane 13.50 Friction modifier 1.00 Isobutylene sulfide 3.34 Dioctyl dithiophosphate tetradeamine salt 0.79 Phosphorus boride polyisobutylene succinimide 3.15 2,5-Bis(tert-dodecyl dithio)-1,3,4-thiadiazole 0.20 polymethylsiloxane 0.01 acrylate ether copolymer 0.01

[0056] Trimethylolpropane: Kinematic viscosity at 40℃ 20.03 mm 2 / s, kinematic viscosity at 100℃: 4.502mm 2 / s, acid value 0.01mgKOH / g, flash point 252℃, pour point -48℃;

[0057] Friction modifier: Its chemical structure is shown in formula (1), where R1 is octyl and R2 is decyl.

[0058]

[0059] The preparation method of the above-mentioned railway locomotive bearing oil composition is as follows: PAO 100, PAO 4, trimethylolpropane ester, friction modifier, sulfurized isobutylene, dioctyl dithiophosphate tetradecylamine salt, phosphobically borate polyisobutylene succinimide, 2,5-bis(tert-dodecyl dithio)-1,3,4-thiadiazole, polymethylsiloxane and acrylate ether copolymer are placed in a high-speed mixer and stirred until homogeneous to obtain the final product.

[0060] Example 4

[0061] A special oil composition for rail transit vehicle gearboxes, the components and contents of which are shown in Table 4 by weight percentage.

[0062] Table 4. Composition and content of special oil composition for rail transit vehicle gearboxes

[0063]

[0064]

[0065] Friction modifier: Its chemical structure is shown in formula (1), where R1 and R2 are both decyl groups.

[0066]

[0067] The preparation method of the above-mentioned special oil composition for rail transit vehicle gearboxes is as follows: mPAO 65, PAO 4, trimethylolpropane ester, friction modifier, sulfurized isobutylene, di(isotridecyl)phosphate tert-alkyl primary amine salt, phosphobically borated polyisobutylene succinimide, methylbenzotriazole di-n-octylamine Mannich condensate, polymethylsiloxane and acrylate ether copolymer are placed in a high-speed mixer and stirred until homogeneous to obtain the final product.

[0068] Comparative Example 1

[0069] Same as Example 1, except that the friction modifier in Example 1 is replaced with a commercially available friction modifier—oleic amide.

[0070] A special oil composition for rail transit vehicle gearboxes, the components and contents of which are shown in Table 5 by weight percentage.

[0071] Table 5. Composition and content of special oil composition for rail transit vehicle gearboxes

[0072]

[0073]

[0074] The preparation method of the above-mentioned special oil composition for rail transit vehicle gearboxes is as follows: PAO 40, PAO 10, pentaerythritol ester, oleamide, sulfurized isobutylene, di(dodecyl) phosphate (diisooctylamine) salt, polyisobutylene succinimide, methylbenzotriazole di-n-butylamine Mannich condensate, polymethylsiloxane and acrylate ether copolymer are placed in a high-speed mixer and stirred until homogeneous to obtain the final product.

[0075] Comparative Example 2

[0076] Same as Example 2, except that the friction modifier in Example 2 is replaced with a commercially available friction modifier—glyceryl monooleate.

[0077] A special oil composition for rail transit vehicle gearboxes, the components and contents of which are shown in Table 6 by weight percentage.

[0078] Table 6. Composition and content of special oil composition for rail transit vehicle gearboxes

[0079] composition Content / wt% PAO 20 78.00 Diisotridecyl adipic acid ester 13.50 Glyceryl monooleate 0.70 ditert-nonyl polysulfide 3.34 Triphenyl thiophosphate 0.79 Boronized polyisobutylene succinimide 3.15 2,5-Bis(tert-nonyldithio)-1,3,4-thiadiazole 0.20 polymethylsiloxane 0.01 Polyacrylate 0.01

[0080] The preparation method of the above-mentioned special oil composition for rail transit vehicle gearboxes is as follows: PAO 20, diisotridecyl adipate, glyceryl monooleate, di-tert-nonyl polysulfide, triphenyl thiophosphate, boronized polyisobutylene succinimide, 2,5-bis(tert-nonyldithio)-1,3,4-thiadiazole, polymethylsiloxane and polyacrylate are placed in a high-speed mixer and stirred until homogeneous to obtain the final product.

[0081] Comparative Example 3

[0082] Same as Example 3, except that the friction modifier in Example 3 is replaced with trimethylolpropane ester.

[0083] A special oil composition for rail transit vehicle gearboxes, the components and contents of which are shown in Table 7 by weight percentage.

[0084] Table 7 Composition and content of special oil composition for rail transit vehicle gearboxes

[0085] composition Content / wt% PAO 100 37.00 PAO 4 41.00 Trimethylolpropane 14.50 Isobutylene sulfide 3.34 Dioctyl dithiophosphate tetradeamine salt 0.79 Phosphorus boride polyisobutylene succinimide 3.15 2,5-Bis(tert-dodecyl dithio)-1,3,4-thiadiazole 0.20 polymethylsiloxane 0.01 acrylate ether copolymer 0.01

[0086] The preparation method of the above-mentioned railway locomotive bearing oil composition is as follows: PAO 100, PAO 4, trimethylolpropane ester, sulfurized isobutylene, dioctyl dithiophosphate tetradecylamine salt, phosphobically boronized polyisobutylene succinimide, 2,5-bis(tert-dodecyl dithio)-1,3,4-thiadiazole, polymethylsiloxane and acrylate ether copolymer are placed in a high-speed mixer and stirred until homogeneous to obtain the final product.

[0087] The gearbox-specific oil compositions prepared in Examples 1-4 and Comparative Examples 1-3, as well as a commercially available product (a certain brand of 75W-90 vehicle gear oil, meeting API GL-5 / MT-1 specifications), were subjected to performance tests. The test indicators and methods are as follows:

[0088] Kinematic viscosity (100℃) / (mm) 2 / s): Refer to GB-T 265-1988 "Determination of Kinematic Viscosity and Calculation of Dynamic Viscosity of Petroleum Products";

[0089] Viscosity index: Refer to GB-T 1995-1998 "Calculation Method of Viscosity Index of Petroleum Products";

[0090] Pour point (°C): Refer to GB-T 3535-2006 "Determination of Pour Point of Petroleum Products";

[0091] Low-temperature apparent viscosity (-40℃) / (mPa·s): Refer to GB / T 11145-2014 "Determination of low viscosity of lubricants";

[0092] Flash point (open cup) / (°C): Refer to GB / T 3536-2008 "Specification for Determination of Flash Point and Ignition Point of Petroleum Products - Cleveland Open Cup Method";

[0093] Anti-foaming properties (24℃, 93.5℃, and then 24℃) / (ml / ml): Refer to GB / T 12579-2002 "Determination of Foaming Characteristics of Lubricating Oils";

[0094] Copper strip corrosion (121℃, 3h) / (grade): Refer to GB / T 5096-2017 "Test Method for Copper Strip Corrosion of Petroleum Products";

[0095] Liquid phase corrosion methods A and B: Refer to GB / T 11143-2008 "Test method for rust prevention performance of mineral oils with inhibitors in the presence of water";

[0096] Load capacity (P) B P D,ZMZ) / (N): Refer to GB / T 3142-2019 "Determination of Lubricant Carrying Capacity - Four-Ball Method";

[0097] Wear scar diameter (392N) / (mm): Refer to NB / SH / T 0189-2017 "Determination of wear resistance of lubricating oil - four-ball method".

[0098] The test data results are shown in Table 8.

[0099] Table 8 Performance Tests

[0100]

[0101] As can be seen from Table 8, compared with the comparative example, embodiment P of the present invention... B The values ​​of ZMZ and wear scar diameter are improved, and the wear scar diameter is significantly reduced. Adding the friction modifier with the structure shown in formula (1) can enhance the oil film strength.

[0102] Test Example 2

[0103] The gearbox-specific oil compositions prepared in Examples 1-4 and Comparative Examples 1-3, as well as a commercially available product (a certain brand of 75W-90 vehicle gear oil, meeting API GL-5 / MT-1 specifications), were subjected to a four-ball friction coefficient test. The test method was based on "SH / T0762-2005 Determination of Coefficient of Friction of Lubricating Oils (Four-Ball Method)". The test results are as follows: Figure 1 As shown.

[0104] from Figure 1 It can be seen that Examples 1-4 have low coefficients of friction and can provide good friction reduction performance. Comparative Examples 1-3 are comparable to the coefficients of friction of commercially available products, with Comparative Example 3 having the highest coefficient of friction.

[0105] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A rail vehicle gear box special oil composition characterized in that, It comprises the following components: friction modifier, solubilizer, extreme pressure anti-wear agent, dispersant, metal passivator, antifoaming agent and base oil, wherein the chemical structure of the friction modifier is shown in formula (1): In formula (1), R1 and R2 are each independently selected from straight-chain or branched alkyl groups of C4-C18.

2. The special oil composition for rail transit vehicle gearboxes according to claim 1, characterized in that, The solubilizing agent is selected from synthetic esters having a kinematic viscosity at 100°C below 10 mm 2 / s.

3. The special oil composition for rail transit vehicle gearboxes according to claim 2, characterized in that, The solubilizer is selected from one or more of pentaerythritol ester, dipentaerythritol ester, trimethylolpropane ester, and diisotridecyl adipate.

4. The special oil composition for rail transit vehicle gearboxes according to claim 1, characterized in that, The extreme pressure anti-wear agent is selected from one or more of the following: isobutylene sulfide, polysulfides, sulfur, phosphorus and nitrogen compounds, di-n-butyl phosphite, alkyl phosphate amine salts, tricresyl phosphate and triphenyl thiophosphate.

5. The special oil composition for rail transit vehicle gearboxes according to claim 4, characterized in that, The polysulfide is a di-tert-octyl polysulfide, a di-tert-nonyl polysulfide, or a di-tert-dodecyl polysulfide.

6. The special oil composition for rail transit vehicle gearboxes according to claim 4, characterized in that, The sulfur, phosphorus, and nitrogen compounds are octadecyl dithiophosphate salt, dioctyl dithiophosphate salt, or didecyl dithiophosphate salt.

7. The special oil composition for rail transit vehicle gearboxes according to claim 4, characterized in that, The alkyl phosphate amine salt is a di(dodecyl) phosphate (diisooctylamine) salt, a diisooctyl phosphate (ditridecylamine) salt, or a di(isotridecyl) phosphate tertiary alkyl primary amine salt.

8. The special oil composition for rail transit vehicle gearboxes according to claim 1, characterized in that, The dispersant is selected from one or more of polyisobutylene succinimide, boronized polyisobutylene succinimide, and phosphobically boronized polyisobutylene succinimide.

9. The special oil composition for rail transit vehicle gearboxes according to claim 1, characterized in that, The metal passivating agent is selected from one or both of benzotriazole derivatives and thiadiazole derivatives.

10. The special oil composition for rail transit vehicle gearboxes according to claim 9, characterized in that, The benzotriazole derivative is a methylbenzotriazole di-n-butylamine Mannich condensate, a methylbenzotriazole di-n-octylamine Mannich condensate, or a methylbenzotriazole di(tetrazine) Mannich condensate.

11. The special oil composition for rail transit vehicle gearboxes according to claim 9, characterized in that, The thiadiazole derivative is 2,5-bis(tert-nonyldithio)-1,3,4-thiadiazole or 2,5-bis(tert-dodecyldithio)-1,3,4-thiadiazole.

12. The special oil composition for rail transit vehicle gearboxes according to claim 1, characterized in that, The antifoaming agent is selected from one or more of polymethylsiloxane, acrylate-ether copolymer and polyacrylate.

13. The special oil composition for rail transit vehicle gearboxes according to claim 1, characterized in that, The base oil is selected from polyalphaolefins having a kinematic viscosity at 100°C in the range of 4-200 mm 2 / s.

14. The special oil composition for rail transit vehicle gearboxes according to claim 13, characterized in that, The base oil is selected from one or more of PAO 4, PAO 6, PAO 10, PAO 20, PAO 40, PAO 100, mPAO 65 and mPAO 150.

15. The special oil composition for rail transit vehicle gearboxes according to claim 1, characterized in that, By weight percentage, it includes the following components:

16. A method for preparing a special oil composition for rail transit vehicle gearboxes as described in any one of claims 1-15, characterized in that, The process includes the following steps: mixing friction modifier, solubilizer, extreme pressure anti-wear agent, dispersant, metal passivator, antifoaming agent and base oil to obtain the final product.

17. The application of a special oil composition for rail transit vehicle gearboxes as described in any one of claims 1-15 or a special oil composition for rail transit vehicle gearboxes prepared by the preparation method described in claim 16 in a rail transit vehicle gearbox.

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