Equipped with smart return-plunger instead of usual stop ring, Double-Acting Locknut Cylinders offer advantages in safety, maintenance, and durability. Use of integrated safety valves protects cylinders against overpressure on return side. Multiple-start thread is provided on plunger for positioning locknut quickly. Because of rounded thread, dirt on plunger can be removed easily. All cylinders are wear-resistant and protected against corrosion.