<HTML><BODY style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; "><DIV><DIV>On Apr 28, 2007, at 9:22 PM, <A href="mailto:McNeilTom@aol.com">McNeilTom@aol.com</A> wrote:</DIV><BR class="Apple-interchange-newline"><BLOCKQUOTE type="cite"><SPAN class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><SPAN class="Apple-style-span" style="font-family: Arial; font-size: 10px; ">Ah, the differential chain hoist. Let me give you a description and a couple photos. There is a single continuous length of endless chain (not the separate operating chain and lift chain of the common geared chain hoist). This chain runs over two wheels on the upper fixed pulley, and one on the lower pulley, thus forming two loops. One of the loops is the 'load loop' (containing the lower pulley) and the other is the 'operating loop' (no lower pulley). </SPAN></SPAN></BLOCKQUOTE></DIV><BR><DIV><SPAN class="Apple-tab-span" style="white-space:pre"> </SPAN>I have what Tom describes as the "common geared chain hoist." Got it from Grainger, and it is still available (keywords manual chain hoist will get you there). I find it quite adequate for the job of pulling plates. I used mine for a Mason CC once, and it would lift the whole piano with ease. (I used a rope block and tackle for the tail to get good balance, but on the initial pull, with friction somewhere keeping the plate attached to the rim, the whole piano went up). I find this rig quite easy and controllable. I can pull the chain with one hand, and guide the plate with the other. Very slow, very controlled, and fast enough when you want to be.<BR><DIV><DIV>Regards,</DIV><DIV>Fred Sturm</DIV><DIV>University of New Mexico</DIV><DIV><A href="mailto:fssturm@unm.edu">fssturm@unm.edu</A></DIV><DIV><BR class="khtml-block-placeholder"></DIV></DIV><BR></DIV><DIV><BR class="khtml-block-placeholder"></DIV></BODY></HTML>