A brake actuator can include a first housing part having a first peripheral wall, a second housing part having a second peripheral wall, and a flexible diaphragm located between the first housing part and the second housing part and compressed between a point of contact on the first housing part and a point of contact on the second housing part. At least one of the points of contact may protrude inwardly from the peripheral walls. The diaphragm may have a peripheral edge that does not extend radially beyond at least one of cylindrical profiles defined by the housing parts.