PT 44540 Motor Brushes fits RIDGID 300 and 535 Threading Machine Motor Replaces Ridgid  Part 44540 Motor Brushes. PT  brand is a quality alternative to Ridgid parts for threading pipe. Compatible with your RIDGID  300 or RIDGID  535 Pipe Threader. Make your pipe threading machine run like new. From the leader in pipe threading replacement parts.