The rear manhole — the silo’s second sealing point
The rear lid is the manhole at the rear of a silo trailer tank — an inspection and discharge opening through which the trailer interior is cleaned, checked and serviced. It is opened less often than the top filling lid, but it operates under the same working pressure as the whole silo, so its tightness is just as important. Closure is ensured by a gasket seated between the rear lid cover and the manhole rim: it keeps the cargo inside, blocks moisture and contamination, and allows pressure to be maintained during discharge.
From the perspective of a network servicing many makes, this category has one specific feature: in some designs the rear manhole is not one but two sealing locations. For Spitzer, the range splits into a silo-side gasket and a gasket for the manhole itself — two separate items. For other makes, like Kässbohrer, the split runs differently: by design generation, into the new and old type. That is why, as with filling lids, the range cannot be organised by universal DN dimensions — we structure it by make, sealing location and manhole type. We run the warehouse in Chorula near Opole to cover the most popular designs on the DACH market and in Poland.
Specification and selection principle
The range covers gaskets for rear silo manholes of many makes. The key is compatibility with the specific manufacturer’s lid, and for Spitzer additionally distinguishing the sealing location.
| Make | Item / type | Notes |
|---|---|---|
| Spitzer | silo side | SF/SK series |
| Spitzer | manhole | SF/SK series |
| Feldbinder | rear lid | EUT/KIP lines |
| Kässbohrer | new type / old type | two variants |
| other makes | rear lid/manhole | on request |
The specific gasket material and dimension is matched to the make and lid type of the given trailer — the seat shape and seal profile are unique to each design, so they cannot be reduced to a single universal value. The gasket material is matched to the trailer’s application: in food-grade circulation, seals in contact with the material must meet hygiene requirements, while in industrial applications the material range is broader.
Compatibility with makes
The gaskets in our range are assigned directly to makes — these are not anonymous substitutes, but components matching the real lids of these manufacturers.
- Spitzer (SF/SK) — the rear manhole of the SF and SK series is sealed with two elements: a gasket on the silo side and a gasket for the manhole itself.
- Feldbinder (EUT/KIP) — the rear inspection and discharge manhole appears on the horizontal EUT and the tipping KIP; on the KIP the gasket must also keep the seal when the tank is tipped.
- Kässbohrer (K.SSK/K.SSL) — the range splits into the new and old lid type.
- other makes — on request, after stating the manufacturer and manhole type.
When ordering, it is essential to state the trailer make and — for Spitzer — to indicate whether the order concerns the silo side or the manhole; for Kässbohrer, whether it is the new or the old type.
When to replace — signals from operation
The rear lid gasket is a wear item, checked at every inspection and replaced at the first signs of lost elasticity. Regardless of the silo make, the same signals point to replacement:
- Hardening and loss of resilience — the gasket does not return to shape after clamping, so the rear manhole does not close evenly.
- Cracks and cuts — they break the continuity of the seal and lead to a leaking manhole under pressure.
- Permanent deformation — an imprinted, flattened cross-section no longer provides proper clamping.
- Confusion with the filling lid gasket — different geometry; the rear manhole takes a dedicated gasket matched to the make and sealing location.
The rear lid gasket works in tandem with the closing mechanism — on lifted silos this means the handle, the eye-and-cross bolt and the spring maintaining the clamping force. Tightness only arises when both elements are sound: a weakened spring or a corroded bolt reduces the pressure on the gasket, and a hardened gasket leaks despite correct tightening. That is why, when servicing the rear lid, we look at the gasket and the closing hardware together.
Chorula warehouse
We keep gaskets for the rear manholes of popular makes in stock at the warehouse in Chorula near Opole (4 km from the A4, about 180 km from the German border); the rest we select and source. The location by the motorway and close to the DACH border shortens delivery times both on the domestic market and to customers in Germany, Austria and Switzerland. Our warehouse processes run within the ISO 9001:2015 quality management system.
We handle selection and order assembly with a mixed fleet in mind: a single shipment can contain gaskets for different makes and sealing locations, as well as the rear lid closing system. For selection and pricing — ask for a quote. Warehouse contact: +48 604 800 869, magazyn@magnumchorula.pl.
Specialist portals
We cover rear lid gaskets in the context of a single make in more depth on our dedicated portals: Spitzer and Feldbinder — there we frame selection in the context of the SF/SK series and the EUT/KIP lines.
Related categories
- Rear lid bolts — universal rear lid closing system, working together with the manhole gasket.
- Filling lid gaskets — gaskets for the top filling manholes of many makes.
- Filling lid bolts — M20 wing bolts for top filling lids.
- Feldbinder parts — parts for the EUT and KIP lines.
Author: Aleksy Pasternak — Managing Partner at PHS Magnum, 20 years in the industry, ISO 9001:2015 internal auditor (DEKRA).
