What is the difference between the Spitzer SF and SK series?

The SF is a fixed-tank silo trailer with a horizontal (lying) vessel and pneumatic-aeration discharge up to approximately 2 bar — well suited to PE/PP granulates, flour, and materials that fluidise readily. The SK is a tipping silo trailer: the vessel is raised hydraulically to assist discharge of heavier, less free-flowing materials such as gravel, sand, sugar, and salt.

What do the abbreviations SF and SK mean on Spitzer trailers?

SF denotes the fixed (non-tipping) version, while SK denotes the tipping version (Kipp). Suffixes include: P (standard), Z (steerable axle / forced steering), and CAL (tipping variant of the SK series). The last two digits of the model number indicate the approximate vessel capacity in m³ — e.g. SF 2745 ≈ 45 m³, SK 2760 CAL ≈ 60 m³.

Which Spitzer series is suitable for gravel and sand?

For gravel, sand, and other heavy bulk materials, the SK series is the better choice — tipping the vessel assists the gravitational flow of material that aeration alone at low pressure would not move. For light granulates such as PE/PP and flour, the SF series with pneumatic-aeration discharge is sufficient.

How do I arrange service or spare parts for Spitzer SF/SK trailers in Poland?

PHS Magnum Chorula services Spitzer SF and SK silo trailers. We cover diagnosis, scheduled maintenance, TDT inspection, and spare parts. Contact: +48 602 716 551, biuro@magnumchorula.pl. Workshop: Chorula near Opole, 4 km from the A4 motorway.

30.04.2025

Spitzer SF vs SK – Silo Trailer Series Comparison

Name: PHS Magnum
Address: ul. Kościelna 9, Chorula, Opolskie, 47-316, PL
Telephone: +48 602 716 551
Price range: $$

DAF silo trailer on an Alpine road transporting bulk materials

In Brief

Spitzer SF – a fixed-tank silo trailer with a horizontal cylindrical vessel, pneumatic-aeration discharge up to approximately 2 bar, capacity circa 23–63 m³. Ideal for PE/PP granulates, flour, starch, animal feed, and lighter mineral materials that fluidise well. Spitzer SK (CAL) – a tipping silo trailer with a hydraulically raised vessel, capacity circa 38–89 m³, pneumatic assist at ~2 bar. Designed for heavier and less free-flowing materials: gravel, sand, sugar, salt, and chemical powders. The choice of series is determined by the cargo. PHS Magnum advises on the right specification, services both series, and stocks spare parts for each.

Spitzer SF vs SK – Two Discharge Philosophies

Spitzer Silo-Fahrzeugwerke GmbH – a German silo trailer manufacturer based in Elztal-Dallau (Baden-Württemberg), a family-owned company with a tradition dating back to 1872 – offers two principal trailer families, each addressing different haulage requirements. Although both look similar from the outside (cylindrical aluminium vessel, three axles, white paintwork), they differ fundamentally in their discharge mechanism.

Both series are a common sight on roads in Poland, Germany, and the Czech Republic – yet haulage companies are often unsure which is the right choice for their cargo. This article explains the differences in practical terms; a similar distinction applies to other manufacturers – see our comparison of Feldbinder EUT and KIP trailers.

Spitzer SF Series – Fixed Tank, Pneumatic-Aeration Discharge

SF Vessel Construction

The Spitzer SF silo trailer has a horizontal cylindrical vessel divided into compartments, with the floor lined with aeration pads – a microporous membrane through which compressed air is injected.

During discharge:

Compressed air (up to approximately 2 bar) passes through the aeration pads
The bulk material fluidises – behaving like a liquid
The material flows into the discharge manifold
The pneumatic stream conveys the material into the destination silo

What Is the SF Series Used For?

The SF series is optimised for materials that fluidise readily:

Good fluidisability (the material “flows” when aerated)
Particle size: from fine powder to granulate

Typical SF cargoes:

Polyethylene (PE) and polypropylene (PP) granulates, recyclates
Wheat, rye, and maize flour
Potato and maize starch
Cement, gypsum, calcium carbonate, fillers, dry mortars
Animal feed, pellets

SF Capacity and Variants

The SF series covers capacities of approximately 23–63 m³. Common models: SF 2734/2 P (~34 m³), SF 2745/3 P (~45 m³), SF 2755/4 P (~55 m³), SF 2763/4 Z (~63 m³). Variants: P (standard, fixed tank) and Z (steerable axle / forced steering).

Spitzer SK (CAL) Series – Tipping Tank, Hydraulic Lift

SK Construction and Operating Principle

The Spitzer SK silo trailer is a tipper – the entire vessel is raised hydraulically during discharge. The tipping action assists the gravitational flow of material that low-pressure aeration alone would not displace. Pneumatic assist at approximately 2 bar supplements the tipping action.

What Is the SK Series Used For?

The SK series is designed for materials that:

Are heavier or do not fluidise readily at low pressure
Have a tendency to cake (hygroscopic materials)
Require mechanical assistance to initiate flow

Typical SK cargoes:

Gravel, sand
Cement, chemical powders
Sugar, salt (hygroscopic materials)
Plastic granulates, wood pellets

SK Capacity and Models

The SK series covers capacities of approximately 38–89 m³. Common models: SK 2745 CAL (~45 m³), SK 2753 CAL (~53 m³), SK 2760 CAL (~60 m³), SK 2766 CAL (~66 m³). Example datasheet for SK 2760 CAL: ~60 m³, GVW 40 t, tare weight ~6.25 t, payload ~33.75 t, three axles × 9 t (BPW), working/test pressure 2 bar, discharge outlet DN 800, 5× hatch DN 450, aluminium vessel and frame.

SF vs SK Comparison Table

Feature	Spitzer SF	Spitzer SK (CAL)
Type	Fixed tank	Tipping (vessel raised hydraulically)
Vessel	Horizontal (lying), cylindrical compartments	Cylindrical, raised on tipping
Discharge mechanism	Pneumatic-aeration	Tipping + pneumatic assist
Working pressure	Up to ~2 bar	~2 bar (assist)
Aeration pads	Yes – primary discharge element	Secondary/supplementary
Typical cargoes	PE/PP granulate, flour, cement, feed	Gravel, sand, sugar, salt, powders
Capacity	~23–63 m³	~38–89 m³
Main service items	Aeration pads, valves	Hydraulic tipping system, valves

Choosing the Right Spitzer Series

Step 1: Identify the Cargo

Start with the material. Plastic granulate or flour? Go with the SF series. Gravel, sand, sugar, heavy or caking material? Choose the SK series.

Step 2: Assess Fluidisability

Materials that flow freely when aerated (granulates, flour) are well served by the SF. Heavy or poorly fluidising materials need the mechanical assistance of the SK tipping system.

Step 3: Balance Payload Against Capacity

The SF at smaller capacities (e.g. SF 2734 ~34 m³) matches volume to mass more closely for dense materials. For light granulates that fill the vessel fully, larger SF variants (~55–63 m³) or the SK series make more sense.

Common Mistakes When Choosing a Series – Real Consequences

Mistake 1: Using an SF for heavy, poorly flowing material

Aeration at low pressure may not be sufficient to move heavier, caking material – resulting in incomplete discharge and blockages. For such cargoes, the tipping SK series is the correct choice.

Mistake 2: Oversized vessel for dense material

Filling a large vessel entirely with high-density material would exceed the maximum authorised mass of the combination (40 t). For cement or gypsum, a smaller capacity that matches volume to mass is the right specification.

Aleksy Pasternak covers diagnosis and common pneumatic discharge faults in silo trailers in detail.

SF and SK Service and Repairs – PHS Magnum

PHS Magnum Chorula services Spitzer trailers across both series. Our workshop is located on the A4 motorway corridor (4 km from the Gogolin junction) and serves customers from Poland, Germany, and the Czech Republic.

What we service: