An opposed piston engine includes an engine housing, at least one cylinder housing coupled to the engine housing, and at least one cylinder supported by the engine housing and by the cylinder housing along an exterior of the engine housing.

A self-charging assembly having a first side wall, a second side wall, a third sidewall, a first chamber, a second chamber, a first valve assembly, and a second valve assembly. The second side wall is disposed within the first side wall. The third sidewall connects the first side wall and the second side wall. The first chamber is defined by the first, second, and third sidewalls. The second chamber is disposed within the first chamber and is defined by the second side wall. The first valve assembly is configured to selectively place an interior portion of the second chamber in communication with an atmosphere outside of the self-charging assembly. The second valve assembly is configured to selectively place an interior portion of the first chamber in communication with the interior portion of the second chamber.

A brake chamber includes a rod member that makes reciprocating motion within a cylinder through a pressure of compressed air or an urging force of a spring, thereby causing a pushrod for activating a brake device of a vehicle to proceed into the brake device. The brake chamber further includes a diaphragm that deforms in response to supply of the compressed air to push the rod member, and a housing that forms an accommodation space for the diaphragm. The housing is connected to the cylinder with a first end of the cylinder being inserted in the housing. The brake chamber further includes a boot member connected to the cylinder and the rod member. The boot member includes a sealing portion to prevent entry of foreign matter into a connection portion between the housing and the cylinder by contacting an inner circumferential surface of the housing.