TOST S-Series Tow Release
Since 1952 TOST company has manufactured releases for gliders. The first product was the manual actuated nose release type “BUG”. 1953 followed the first TOST safety release (Universal), that has been installed near to the center-of-gravity. Its automatic release at a defined cable angle made the winch launch safe.
TOST releases are the standard worldwide for safe gliding starts for all types of starts and are being operated “from Australia to Cyprus”. In total, more than 73.000 units have been produced. All are still being serviced, also those units from the very beginning. Most of the releases are still serviceable and even in service for further decades.
Overhaul (OH) releases are subject to availability. Most tow releases are in stock. Some may require special order.
W&W strongly recommends taking pictures of your tow release needing replacement and emailing to us for type verification.
History of TOST Releases
During the decades, TOST releases have been developed further and optimized as well. The sequence of the release types is as follows:
For the nose and tail releases: BUG - E 72 - E 75 - E 85
For the center-of-gravity releases: UNIVERSAL - KK - G 72 - G 73 - G 88
One important step to high dimensional accuracy and rigidity of the releases was
the use of precision casting components: hook, segment, ring automatic as well as fine cast release housing as successor of the welded release housing (up to type E 72 and G 72). When used in vintage gliders, please always check the installation space: narrow release brackets possibly may not allow the installation of the latest release types G 73 / G 88 and E 75 / E 85, which need a bit more space.
A further milestone was the increase of the cable force from 11,7 kN for the predecessor types to 14,1 kN for the E 85 and G 88 series.
The exchange of the elder release types against the recent ones has always been guaranteed through the retention of the outer dimensions and fixation holes of the releases.
Important Operating Advise to the Connecting Ring Pair
Connecting ring pairs are vital for the safe connection and reliable separation of tow
cable and tow release. The type certification stipulates that every TOST tow release must be operated only with a ring pair meeting the aeronautical standard LN 65091.
Such a ring pair must be stamped with the manufacturer's name and the standard number. Welded ring pairs are generally prohibited and imply a potential danger for the pilot. Their use voids our warranty for the release. Welded rings damage the release. Moreover, undersized or deformed rings can cause the ring pair to jam the release and inhibit correct operation under load.
Ring pairs must be visually checked and measured at regular intervals to ensure correct operation. Ring pairs that deviate from the standard dimensions must be replaced.
Send in your core tow release for an $80 credit (most releases).
Care and Cleaning
The release is largely protected against corrosion. But certain components like the hook cannot get surface protection due to strength reasons. Therefore regular cleaning and servicing is imperative for maintaining the required security level.
During operation and especially when landing away from paved runways, your release is exposed to dirt and pollution. So it is important to check the release before and at the end of every flight operation and to clean it if necessary. This point is indispensable especially if not used daily.