I acquired this pair of ascenders from Darrell Tomer in 1985, but they were made in the late 1960s, and by the time Prusiking was written (1973) they were no longer available. Roloff Ascenders were developed as a cheap alternative to the "expensive" Jumar, which cost about $15.00 at the time. They should be viewed as ambitious homemade devices. A significant number appear to have been made; I'd be very interested in knowing how many. Mine have serial number 17, which is stamped on the inside. Darrell Tomer loves to modify equipment, and his two Roloff ascenders were recipients of substantial modification. Fortunately he saved all the parts he removed, so I was able to restore them to something resembling their original condition. Allen Padgett gave me a third Roloff ascender (left hand, serial number 51) in 2003.
The Roloff ascender uses a cast aluminum frame, cam, and cam safety, and are assembled with two machine screws, washers, and nuts . None of the parts are finished. The frame is patterned after the old Jumar frame, but the rope attachments have been changed to one 16 mm. hole below the handle and a second 16 mm. hole above the cam. The holes in the rope channel and the handle portion of the frame seen in the photographs are later additions due to Darrell's tinkering, as is the steel sheet metal wear plate added inside the channel. One of the cam springs is very strong, the second is very weak. I think the former is original and the latter is a replacement, since the two cam safety springs are similar to the strong one. The cam and cam spring are mounted on a standard 3/16 inch machine screw with a washer and fluted nut. The screw is center punched so the nut won't accidentally come off.The cam teeth are hand filed in a (4.3)^5 pattern (See Johnston, J. and D. Myrick, Homemade Ascender Cams, The Huntsville Grotto Newsletter, v. IX, # 6, June-July, 1968, pp. 81-85 for one way to do this). Needless to say the teeth are crude by commercial standards. The cam safety is cast in the Jumar gray series Version A pattern. The safety and safety spring are mounted on a 3/16 inch machine screw which was originally threaded directly into the frame. The threads are stripped out on my left hand ascender, so a longer screw and hex nut have been substituted.
The Roloff frame is not as nicely finished as the Jumar. Thrun quotes some anonymous test results indicating that the Roloff is weaker than the same vintage Jumar. The lower sling attachment point is superior to the gray series Jumars that the design was based on, but the upper is not. The Jumar design is easier to grip from above.
The cam is definitely inferior to other eccentric cam ascender cams. The teeth are very poorly formed, uneven, dull, and wear quickly. The cam casting and subsequent machining is very crude The cam safety is also poorly finished. The workmanship on this ascender is definitely not up to commercial standards, but remember, this was not a commercial ascender. The cam is very loosely mounted on the cam pivot, and with slight sideways pressure the cam can hang up on the side of the rope channel. This keeps the cam from closing, and can ruin your day if it happens at an inopportune moment.
Like the early Jumars, the Roloff is very easy to use. The cam can be opened easily with either hand. I find the Roloff occasionally slips, undoubtedly since the teeth on mine are heavily worn. My Roloff ascenders have hand filed cam teeth, but at the 1989 O.T.R., Bob Leibman showed me a pair of "original" Roloff Cams with cast conical teeth. The teeth were quite long (perhaps 1.5 to 2.0 mm.). I do not know whether there were several cam versions, whether one of us does not have true Roloff cams, or whether Darrell hand filed the teeth on his pair once the original teeth wore out.
I find it amazing that anyone would actually attempt to duplicate a Jumar rather than buy one. Since the Roloff has been out of production for 20 years, I doubt that too many can be found. The Jumar is a better device anyhow, so I don't recommend the Roloff for caving use. It makes an excellent museum piece, and belongs in the hands of a collector. A few years ago a pair sold at the N.S.S. Convention for about $500, but that certainly is unlikely to ever happen again (the interested parties now all having them), $150 would be my guess.