Patents: “Device for lowering a load along a line”
The patents behind the Exit Traveler’s automatic brake, filed in 1984 by its Dutch developers, and the 1988 assignment of the U.S. patent to R.A.W. Rescue Products.
U.S. Patent 4,588,046
- Title: Device for lowering a load along a line
- Inventors: Abram P. van der Neer (Krimpen a/d IJssel) and Harm W. Holman (Doetinchem), the Netherlands
- Assignee at grant: van der Neer International B.V., Doesburg, the Netherlands
- Filed: November 5, 1984 (appl. no. 668,332), with priority from Dutch application 8400368 of February 6, 1984
- Granted: May 13, 1986; 1 claim, 2 drawing figures; Int. Cl. A62B 1/14
Abstract: “Escape device comprising a holder 1 in which is guided a flat belt 23 and which accommodates at least one brake shoe 12a on which a force is exerted depending upon the weight of the load and which is directed toward the belt 23.”
The description explains the idea behind the design: a flat belt runs between two brake shoes, and the load pulls on rods with springs that press the shoes harder against the belt as the weight increases, so that “the speed which with the load is lowered is independent of the weight of the load within a large range.” The belt is wound on a reel which, “in a preferred embodiment,” is “provided in a detachable cassette,” and the patent notes that “unconscious people can be brought to safety” with the device. This matches the cassette, brake and tape seen in the X-ray view.
Assigned to R.A.W. Rescue Products, 1988
The U.S. Patent and Trademark Office’s assignment records, as shown in the legal events on Google Patents, list an assignment of U.S. Patent 4,588,046 to R.A.W. Rescue Products, Inc., Ambler, Pa., effective September 8, 1988 and recorded October 28, 1988 (reel/frame 004969/0517). The fourth-year maintenance fee was paid on November 13, 1989; the patent later lapsed for non-payment of maintenance fees (effective May 15, 1994).
This record supports Rick Denzien’s account that R.A.W. bought the patents, the production rights and the transfer of know-how, and began U.S. production of the Exit Traveler in Ambler, Pennsylvania (Rick Denzien, personal communication, October 27, 2026; see Rick Denzien and History).
The patent family
The same invention was filed in several countries, all claiming the Dutch priority of February 6, 1984. The European patent names both Van der Neer International BV and Holman Holland BV as applicants.
| Country | Number | Dates |
|---|---|---|
| United States | US 4,588,046 | granted May 13, 1986 (appl. no. 668,332, filed Nov. 5, 1984) |
| European Patent | EP 0 153 509 B1 | application EP 84201610, filed Nov. 6, 1984; A1 published Sept. 4, 1985; B1 granted Oct. 5, 1988 |
| Netherlands | NL 8400368 A | filed Feb. 6, 1984 (the priority application); published Sept. 2, 1985 |
| Canada | CA 1228338 A | |
| Australia | AU 587567 B2 | |
| Germany | DE 3474413 D1 | |
| Japan | JP S60-165961 A | |
| Denmark | DK 510684 | |
| Austria | AT 37663 T |
European patent PDF Dutch application PDF
Related
- The Dutch press of 1985 on the inventors and their company: The Exit Traveller in the Dutch press.
- Van der Neer also filed a European application for an “Evacuation mattress” (EP 0 224 552 A1).
Patent documents are public records. Data from the patent documents and from Google Patents (bibliographic data and USPTO legal events), read on October 27, 2026.