The closer hidden in the box above your aluminium door is the part that decides whether it closes quietly and latches, or slams and swings. When it fails we replace it — Dorma, Axim, Adams Rite or universal-fit — with a new arm, channel and pivot, in one visit, with the premises open.
A transom closer is a hydraulic door closer mounted inside the transom — the horizontal box section above the door — rather than on its face. A spindle drops from the closer into a slide arm let into the top rail of the leaf, and the leaf itself turns on a bottom pivot in the threshold. Because nothing shows on the door, transom closers were specified on the great majority of UK aluminium shopfronts, office entrances and public-building doors from the 1980s onward, and they are still the standard on new glazed entrances today.
They fail the way any hydraulic closer fails: the seals wear, the oil that damps the closing swing bypasses the speed valves, and the door either drops shut with a bang or drifts and stops short of the latch. The give-away is that the adjustment screws stop doing anything. A closer that will not hold an adjustment is not a closer that needs adjusting — it is one that needs replacing. On doors of this age the arm, the slide channel and the bottom pivot have usually worn with it, which is why we change them together.
The units we meet most often are the Dorma RTS 85 and its current successor the RTS 88, Axim concealed closers, and Adams Rite units such as the ARC51N. All share a similar transom footprint, so a like-for-like or universal-fit replacement almost always drops into the existing box without any work to the frame.
Film the door closing on your phone and send it over. Thirty seconds of footage usually tells us which of these it is, and what to put on the van.
No damping on the closing swing. The oil is bypassing the valves — the closer has failed hydraulically.
The leaf drifts and never quite closes. Weak spring, worn arm, or a dropped door on a worn pivot fighting the closer.
Bottom pivot bearing worn oval; the door has dropped and is loading the arm unevenly. Change pivot and closer together.
Worn arm bush, cracked slide channel or loose spindle plate. Often repairable without a new closer if caught early.
The closer body has lost its seal. Replacement only — the unit cannot be resealed in situ.
The entrance has been abandoned for a side door. We treat these as priority call outs and aim to reopen the door same day.
Transom closers are the most common single repair we do. These are recent ones, each with before-and-after photographs and video.
Most of the transom closers we replace are original to the building, so the brand on the old unit tells us a lot about the door. Dorma’s RTS 85 was the UK default through the 1980s and 1990s and its successor the RTS 88 drops straight into the same box; Axim closers are the other common pattern on shopfront screens; Adams Rite units turn up on heavier commercial entrances. Where the original is end-of-line we fit a universal-fit concealed closer sized to the existing housing, and we document the swap so your compliance file shows what was fitted and when.
Read more on the hardware side in our Dorma brand guide, the failed transom closers fault page and the guide to transom closer failure signs. If the fault is at the bottom of the door rather than the top, start with transom closer and bottom pivot repair or floor spring repair.
Shopfronts, offices, surgeries and schools across the UK — the right closer, arm and pivot on the van for a single-visit fix.
A transom closer is a hydraulic door closer concealed inside the box section — the transom — above a commercial door. It drives the leaf through a slide arm let into the top rail, so nothing is visible on the face of the door. Dorma RTS 85 and RTS 88, Axim and Adams Rite units are the ones we see most on UK aluminium shopfronts and office entrances.
The door slams, or drifts and stops short of the latch, and turning the closing and latching adjustment screws makes no difference. Both symptoms mean the hydraulic seals inside the closer have gone and the oil is bypassing the valves. A closer in that state cannot be adjusted back to health — it needs replacing.
The closer body itself is a sealed unit and is not repairable once it has lost hydraulic control. What we can often repair is everything around it — a worn or broken arm, a damaged slide channel, a loose spindle plate or a worn bottom pivot. Where the closer has failed we fit a new unit, and we always fit a new arm and channel with it.
Yes. The leaf is lifted off its bottom pivot and set aside, the transom cover is removed, the old closer and arm come out and the new unit goes in. The leaf is then re-hung and the closing speed, latching action and hold-open (where specified) are set. On a single door this is usually under two hours, and the premises stay open through the adjacent leaf or a side entrance.
Yes. We carry Dorma RTS 88 and universal-fit concealed closers, arms, channels, spindle plates and bottom pivots as standard stock, so most transom closer replacements are completed on the first visit. If you photograph the closer body with the transom cover off, we will identify the exact pattern before we come out.
It depends on the closer pattern and whether the bottom pivot and arm need changing at the same time, which they usually do on a door of this age. Send us a photo or short video of the door and the fault and we will quote the same day — most transom closer jobs are quoted without a site survey.
Send a photo and a short description of the fault and we’ll come back with a fixed-price quote the same day. Most diagnoses don’t need a site visit.
Get in touch
Head Office:
Commercial Door Maintenance and Security Ltd
61 Bridge Street,
Kington,
HR5 3DJ
t: 0800 774 7998
e: info@cdms-ltd.co.uk
Office Hours
Mon - Sat: 8am - 10pm
Sun: Closed
