GREASE COMPOSITION, MACHINE COMPONENT, AND STARTER OVERRUNNING CLUTCH
A silicone grease composition is disclosed. The silicone grease composition contains a silicone oil (A) and zinc dialkyldithiocarbamate (BX) as an extreme-pressure additive. The silicone grease composition contains substantially no zinc dialkyldithiophosphate (BX). The silicone grease composition achieves high friction characteristics and wear characteristics.
1 . A grease composition comprising:
a silicone oil (A); and
zinc dialkyldithiocarbamate (B);
wherein the grease composition comprises substantially no zinc dialkyldithiophosphate (BX).
2 . The grease composition according to claim 1 , wherein a content of the zinc dialkyldithiophosphate (BX) is 0.01 mass % or less relative to the total amount of the grease composition.
3 . The grease composition according to claim 1 , wherein a content of the zinc salt (B) is from 5 mass % to 30 mass % relative to the total amount of the grease composition.
4 . The grease composition according to claim 1 , further comprising at least one type of thickener (C) selected from the group consisting of lithium soap and lithium complex soap.
5 . The grease composition according to claim 1 , wherein a content of the silicone oil (A) is in a range of 50 mass % to 95 mass % relative to the total amount of the grease composition, and the silicone oil (A) has an aromatic hydrocarbon group per molecule.
6 . The grease composition according to claim 1 , wherein the grease composition is a grease composition for a power transmission device.
7 . A machine component comprising the grease composition according to claim 1 .
8 . The machine component according claim 7 , wherein the machine component is a clutch or a torque limiter mechanism.
9 . An overrunning clutch comprising the grease composition according to claim 1 in a clutch cam chamber formed by an outer clutch and an inner clutch.
10 . The grease composition according to claim 2 , wherein a content of the zinc salt (B) is from 5 mass % to 30 mass % relative to the total amount of the grease composition.
11 . The grease composition according to 10 , further comprising at least one type of thickener (C) selected from the group consisting of lithium soap and lithium complex soap.
12 . The grease composition according to claim 11 , wherein a content of the silicone oil (A) is in a range of 50 mass % to 95 mass % relative to the total amount of the grease composition, and the silicone oil (A) has an aromatic hydrocarbon group per molecule.
13 . An overrunning clutch comprising the grease composition according to claim 12 in a clutch cam chamber formed by an outer clutch and an inner clutch.