Tie rod style hydraulic cylinders use high strength threaded steel rods to hold the two end caps to the cylinder barrel. This method of construction is most often seen in industrial factory applications. Small bore cylinders usually have 4 tie rods, while large bore cylinders may require as many as 16 or 20 tie rods in order to retain the end caps under the tremendous forces produced. Tie rod style cylinders can be completely disassembled for service and repair.
The National Fluid Power Association (NFPA) has standardized the dimensions of hydraulic tie rod cylinders. This enables cylinders from different manufacturers to interchange within the same mountings.
Tie rod cylinders are usually a bulkier design but are more often offered as standard series with short delivery times, so are more readily available. High-strength chrome steel rods are used, so most cylinders of this design are rated for no higher than 3,000 psi. These designs are most often used in plastics or machine tools for industrial use.