What Seal Types Are Commonly Used in Concrete Mixers?

Number of hits：72025-08-23 11:52:19　

Concrete mixers are a common piece of machinery on construction sites, operating almost around the clock. They must handle a mixture of sand, gravel, powder, cement, and admixtures, while maintaining stable operation under constant vibration and high loads. The stable, high-load operation of concrete mixers is closely linked to the various seals within them. Seals play a crucial role in driving the mixing drum, operating the hydraulic system, and protecting the reducer and bearings. Today, let's explore the various seal types used in concrete mixers.

Common seal series and application parts of concrete mixers?

1. Rotary Shaft Oil Seals

The drive shaft and gearbox are the main battlegrounds for oil seals. Common materials include Nitrile Rubber (NBR) for oil resistance and wear resistance, and Fluoroelastomer (FKM) for high temperature and chemical resistance. Under normal conditions, they handle pressures of 0.3–0.5 MPa with ease. I recall one case where a customer swapped an FKM seal for a cheaper NBR version. In the summer heat, with long operating hours, the lip hardened and cracked, causing oil leakage in less than two months. Once we replaced it with the proper high-temp FKM seal, the problem disappeared.

2. O-Rings

In the hydraulic system, O-rings are everywhere — cylinder end caps, valve blocks, fittings. Materials range from NBR and FKM to polyurethane (PU). Concrete mixer hydraulics often run at 16–25 MPa, with pressure spikes reaching 35 MPa during certain actions. That means compression ratio, hardness, and media resistance all have to be spot-on.

3. Hydraulic Cylinder Seal Kits

These include piston seals, rod seals, guide rings, and wiper seals. Wipers are especially critical in mixers because the discharge area is full of dust and slurry. If debris isn’t scraped off, the piston rod can get scored quickly. For one overseas client, we replaced their single-lip wiper with a dual-lip design — the outer lip scraped off mud, the inner lip kept oil in. Service life doubled.

4. Skeleton Oil Seals & Combination Seals

Planetary gearboxes and slewing bearings often use NBR + metal skeleton or FKM + stainless steel skeleton seals. They prevent grease loss and block cement dust. Distributors often stock multiple sizes because shaft diameters vary between mixer brands, and a precise fit is critical for replacement.

NQKSF Services

· Ready-to-Ship Standard Parts: Over 10,000 SKUs of O-rings, oil seals, and more — urgent orders ship the same day.

· Custom Solutions: From material selection to design and testing, we handle non-standard seals for high-temp, high-pressure, or corrosive environments.

· Technical Support: With 30+ years of experience, we help clients optimize sealing systems, cut maintenance costs, and boost reliability.

Advantages

· In-house manufacturing for quality control

· Full range of common sizes in stock

· Products shipped to 80+ countries

· Recognized as Provincial Technology Innovation Center, Specialized & Innovative Enterprise, and High-Tech Enterprise

· Long-term partnerships with global brands

· Core member of a specialized industrial cluster

FAQ

Q: How fast can you deliver non-standard seals?

A: 7–15 days after design confirmation, with expedited options available.

Q: Can I mix small quantities in one order?

A: Yes — it helps reduce your inventory pressure.

Q: How can I extend seal life in high-dust environments?

A: Use wear-resistant materials, upgrade wiper designs, and add protective covers where possible.

Concrete mixer sealing system isn’t just one part — it’s a coordinated set of components working together. Choosing the right seals is like giving the machine a tailored suit of armor, allowing it to survive years of harsh conditions. NQKSF is ready to provide both the products and the know-how to help distributors, wholesalers, and end users build a stronger defense line.