The challenge
So far we’ve talked about consistently cutting down on parts and about financially quantifiable assembly benefits. The inner values of our second-generation AGL® furniture also include a positive mechanism that really holds up. Wobble is something to which door handle furniture definitely should not be prone. Unsightly sagging handles are nevertheless a common occurrence, unfortunately, especially on heavily frequented doors or where heavy lever handles are used in combination with locks of inferior quality. This is a thoroughly unsatisfactory state of affairs from both a visual and a technical angle.
Practice hitherto
Positive mechanism A or B, Class 3 or 4: you generally have to opt for one or the other where furniture by our fellow-competitors is concerned. Hence, Public Project buildings have hitherto had to make do with a ‘B’ positive mechanism and Class 3 at best. Class 4 is stipulated for heavy and heavily frequented doors, however. And an ‘A’ positive mechanism is ultimately not much more than a spring support that lent the bearings some sense of strength prior to assembly of the hardware. A truly positive mechanism needs to be a bit more than that.
Our solution
In addition to there being compensating bearings on both sides, our second-generation AGL® hardware features a completely reconceived positive mechanism. It meets criteria A and B as laid down in EN 1906. EN 1906 states Criterion A as encompassing “spring support” whilst Criterion B supplements this with a return action on the door handle by means of spring pre-tensioning with a view to attaining a predefined position.
The carrier plate central to FSB’s positive mechanism is characterised by two springs and the attendant bump stops. The bearing for the springs is made of toughened steel set within glassfibre reinforced plastic, the carrier plate is made of stainless steel, and the shank is borne in Teflon-coated, low-friction sliding-bearing bushings, all of which guarantees enduring wear/ maintenance-free functioning of AGL® furniture. The Class A and B positive me chanism – particularly rugged and accurate in the FSB version – is a key entity in ITT specification practice on its own, as its return action is qualitatively far superior to all commonly marketed solutions and therefore enjoys niche status relative to these. In combination with the ITT specification criteria for AGL® furniture, FSB’s positive mechanism yields additional synergies for FSB ITT exercises. Pin-point criteria, easy-grasp benefits for investors and clients, and quantifiable differences are all effective means of demarcation from comparable alternatives: a valuable benefit notably for architects and planners in their ITT specification work.
But AGL® has yet more to offer. The fourth benefit concerns the offsetting of a further technical shortcoming rooted in the design of a great many locks: that of door handles being pushed 2° above the horizontal by the force of the lock spring.