In Brief
Spitzer SF – non-tipping silo trailer with a horizontal tank, discharged pneumatically (gravity-aerated) at around 2 bar through aeration pads (capacity approx. 23–63 m³). Best for: plastic granules (PE, PP), flour, starch, granulated salt, sugar — free-flowing cargo fluidised by aeration. Spitzer SK – tipping silo trailer (CAL) with a hydraulically raised tank discharged by tipping, with pneumatic assist at around 2 bar (capacity approx. 38–89 m³). Best for: denser, heavier bulk such as gravel, sand, sugar, salt, plastic granulate and chemical powders. Choosing the wrong series causes incomplete discharge, accelerated wear and excessive downtime. PHS Magnum advises on model selection and services both Spitzer series.
Two Design Philosophies, One Product Family
Spitzer Silo-Fahrzeugwerke, the German manufacturer based in Elztal-Dallau, builds two fundamentally different silo-trailer families — not to confuse operators, but because bulk cargo handling has no universal solution. Light free-flowing granules and dense heavy bulk look similar from a distance. In practice, their flow characteristics, bulk density and the discharge method they need differ dramatically.
Both trailer types are common on European roads. Both are cylindrical and move dry bulk. But their internal engineering — and the maintenance requirements that follow — are entirely different. A similar split between aeration and pressure discharge exists at other manufacturers — see our comparison of Feldbinder EUT and KIP trailers.
Spitzer SF: Non-Tipping, Gravity-Aerated Discharge System
How the SF Works
The Spitzer SF trailer uses a horizontal tank that stays in place during discharge — the cargo is fluidised and pushed out pneumatically rather than by tipping. The floor of the tank is lined with microporous aeration pads — permeable textile membranes.
During discharge:
- Compressed air at a working pressure of around 2 bar is introduced through the aeration pads from below
- The bulk material becomes fluidised — behaving like a liquid
- The fluidised material flows by gravity through bottom outlet valves into the discharge manifold
- A pneumatic conveying line carries the material to the destination silo
This is a low-energy discharge process. The compressor works at relatively low pressure, the material moves gently, and the discharge rate is consistent and controllable.
FIBC-Compatible Loading
The SF’s top-loading design via roof hatches makes it directly compatible with FIBC (big bag) and pneumatic blow-in loading systems. The horizontal tank layout also allows partial loading — sections can be filled and discharged in a controlled sequence.
What the SF Handles Well
Ideal cargo for Spitzer SF:
- Plastic granules: PE (LDPE, HDPE), PP, PVC, ABS, PET — the dominant use case in Central Europe
- Wheat, rye and corn flour
- Granulated and powdered sugar
- Potato and corn starch
- Industrial and food-grade salt (fine)
- Dry milk powder (food-grade pads required)
- Semolina, dry yeast
Typical tank volume: approx. 23–63 m³
Working pressure: around 2 bar
Spitzer SK: Tipping Discharge System
How the SK Works
The Spitzer SK series is a tipping silo trailer (CAL designation). The tank is raised hydraulically and the cargo is discharged by tipping the vessel, supported by pneumatic assistance. This handles denser and heavier bulk that does not fluidise readily by aeration alone.
Capacity runs from approximately 38 to 89 m³. Working pressure for the pneumatic assist is around 2 bar. The hydraulic tipping mechanism — rather than aeration pads — is the primary discharge means.
What the SK Handles Well
Ideal cargo for Spitzer SK:
- Gravel and sand
- Cement
- Sugar and salt
- Plastic granulate
- Wood pellets
- Chemical powders
Typical tank volume: approx. 38–89 m³
Working pressure (pneumatic assist): around 2 bar
SF vs SK: Comparison Table
| Feature | Spitzer SF | Spitzer SK |
|---|---|---|
| Tank design | Non-tipping, horizontal tank | Tipping, hydraulically raised tank |
| Discharge system | Pneumatic / gravity-aerated (pads) | Tipping + pneumatic assist |
| Working pressure | around 2 bar | around 2 bar |
| Aeration pads | Yes — primary element | Supplementary |
| Typical cargo | Granules, flour, sugar | Gravel, sand, cement, chemical powders |
| Typical volume | approx. 23–63 m³ | approx. 38–89 m³ |
| Primary maintenance | Aeration pads, bottom valves | Tipping gear, valves, seals |
Choosing the Right Spitzer Model: A Practical Framework
Step 1: Identify the cargo
Start with the actual material being transported. Light free-flowing granules (PE/PP), flour, starch, sugar? SF. Dense, heavy bulk such as gravel, sand, cement or chemical powders that suits tipping discharge? SK. This single step eliminates most doubt.
Step 2: Check bulk density and flowability
Light, free-flowing materials fluidise readily and discharge well with the SF’s aeration system. Denser, heavier or poorly fluidising materials are better matched to the SK’s hydraulic tipping discharge, which moves the load out by raising the tank rather than relying on aeration alone.
Step 3: Capacity requirement
The SF series covers approximately 23–63 m³; the SK series covers approximately 38–89 m³. Where a larger volume is needed for a low-density cargo, the upper SK range may be the only fit.
Real-World Errors When Selecting Spitzer Models
Error 1: Running aeration-only SF on unsuitable dense cargo
Operators buy a used SF because it’s cheaper, then run a dense or abrasive material it isn’t suited to. Result: aeration pads wear or fail prematurely, incomplete discharge and valve blockages — costly pad replacement every season instead of every 3–5 years.
Error 2: Choosing SK where SF would serve
For light free-flowing granules, the SF’s pneumatic aeration discharge is gentle on the product and efficient. A tipping SK is heavier mechanical equipment than such cargo requires — added complexity and maintenance with no benefit.
Error 3: Ignoring capacity limits
Matching the wrong series to the required volume — for example needing far more than 63 m³, which only the SK range reaches — leads to repeated under-loading or the wrong trailer entirely.
Service, Parts and Technical Support – PHS Magnum
PHS Magnum in Chorula, near Opole, Poland has been servicing Spitzer silo trailers for over 30 years. Our workshop is located 4 km from the A4 motorway (Gogolin junction), making it accessible for operators from Poland, Germany and the Czech Republic.
We service both Spitzer series — SF (non-tipping) and SK (tipping): TDT (Polish Transport Technical Supervision) pressure vessel inspections, aeration pad replacement, valve overhaul, pneumatic system diagnostics, spare parts supply.
Call for service or technical advice: +48 602 716 551
Related: Spitzer trailer service · Silo trailer spare parts · TDT revision · Repair & renovation
