Guarantees	3 Months Ended
Oct. 31, 2011
Guarantees [Abstract]
Guarantees	Note H – Guarantees The Company and Caterpillar Inc. equally own the shares of Advanced Filtration Systems Inc. (AFSI), an unconsolidated joint venture, and guarantee certain debt of the joint venture. As of October 31, 2011 the joint venture had $12.2 million of outstanding debt, of which the Company guarantees half. For the three months ended October 31, 2011, the Company recorded $0.7 million of earnings for this equity method investment. The Company recorded $0.2 million of earnings for this equity method investment during the three months ended October 31, 2010. During the three months ended October 31, 2011 and 2010, the Company also recorded royalty income of $1.7 million related to AFSI. At October 31, 2011, the Company had a contingent liability for standby letters of credit totaling $11.4 million that have been issued and are outstanding. The letters of credit guarantee payment to third parties in the event the Company is in breach of insurance contract terms or other commercial contract terms as detailed in each letter of credit. At October 31, 2011, there were no amounts drawn upon these letters of credit.

Guarantees

3 Months Ended

Oct. 31, 2011

Note H – Guarantees

The Company and Caterpillar Inc. equally own the shares of Advanced Filtration Systems Inc. (AFSI), an unconsolidated joint venture, and guarantee certain debt of the joint venture. As of October 31, 2011 the joint venture had $12.2 million of outstanding debt, of which the Company guarantees half. For the three months ended October 31, 2011, the Company recorded $0.7 million of earnings for this equity method investment. The Company recorded $0.2 million of earnings for this equity method investment during the three months ended October 31, 2010. During the three months ended October 31, 2011 and 2010, the Company also recorded royalty income of $1.7 million related to AFSI.

At October 31, 2011, the Company had a contingent liability for standby letters of credit totaling $11.4 million that have been issued and are outstanding. The letters of credit guarantee payment to third parties in the event the Company is in breach of insurance contract terms or other commercial contract terms as detailed in each letter of credit. At October 31, 2011, there were no amounts drawn upon these letters of credit.