Mick, I'm not sure. So I'll let you read the patent letter. A lot of old patents are now online, finding them is half the fun!
http://www.newsouthernview.com/pdfs/nsv_shm_lindseywagon_patent.pdf < Link To http://www.newsouthernvie...indseywagon_patent.pdf
http://www.newsouthernview.com/pdfs/nsv_shm_lindseywagon_patent.pdf < Link To http://www.newsouthernvie...indseywagon_patent.pdf