A centralizer is located in a passage of a tubular body of a wellhead assembly for centralizing well tools lowered through the passage. Centralizing members have outer ends mounted to axially extending stationary hinge members, which are mounted to the tubular body in a circular array around a circumference of the passage. A cam and a slot are located between the outer end of each of the centralizing members and the stationary hinge member. Each of the slots has an upward inclined portion, a downward inclined portion, and a neutral position located between the upward and downward inclined portions. A spring urges the cam and the slot to the neutral position, which orients the centralizing members radially inward.