Business Segment Information (Details) (USD $)	3 Months Ended		6 Months Ended
	Jul. 02, 2011	Jul. 03, 2010	Jul. 02, 2011	Jul. 03, 2010
Net sales
Net sales	$ 122,029,000	$ 121,500,000	$ 230,370,000	$ 240,745,000
Operating income
Operating income	20,447,000	26,258,000	37,946,000	45,940,000
Total segment operating income	21,805,000	27,104,000	40,042,000	48,329,000
Items not allocated to segment operating income	(1,358,000)	(846,000)	(2,096,000)	(2,389,000)
Interest expense	(98,000)	(62,000)	(195,000)	(124,000)
Interest income	110,000	98,000	289,000	122,000
Income before income taxes	20,459,000	26,294,000	38,040,000	45,938,000
Friction Control Products [Member]
Net sales
Net sales	65,797,000	79,692,000	126,692,000	159,474,000
Operating income
Operating income	11,526,000	20,339,000	21,400,000	36,883,000
Velocity Control Products [Member]
Net sales
Net sales	25,331,000	15,114,000	44,957,000	29,347,000
Operating income
Operating income	5,884,000	3,952,000	11,710,000	7,327,000
Other Industrial Products [Member]
Net sales
Net sales	30,901,000	26,694,000	58,721,000	51,924,000
Operating income
Operating income	$ 4,395,000	$ 2,813,000	$ 6,932,000	$ 4,119,000