Single-Acting vs Double-Acting Forklift Steering Cylinders: Which Does Your Machine Use?

The question of whether a forklift uses a single-acting or double-acting steering cylinder is not always obvious from looking at the machine — yet it is one of the most fundamental specification questions a procurement team or maintenance engineer must answer before ordering a replacement unit. Installing the wrong cylinder type will result in a machine that steers in only one direction under hydraulic power, relies on spring return that may not exist, or fails to reach full steering lock — any of which renders the forklift unusable in the aisle widths it was designed to navigate.

This article explains the working principles of both single-acting and double-acting forklift steering cylinders, identifies which forklift types use each configuration, and provides guidance on how to confirm the correct specification when sourcing replacements.

How Single-Acting Forklift Steering Cylinders Work

A single-acting cylinder accepts hydraulic pressure on only one face of the piston — typically the cap end, which drives the piston rod outward (extension stroke). For steering applications, the extension stroke pivots the rear steering axle in one direction — let us say, turning the forklift left. When the operator turns the steering wheel back to the right, the hydraulic control valve exhausts the pressure from the cap-end chamber and allows the return mechanism to push the piston back to retract the rod.

In forklift steering systems, this return mechanism is typically a mechanical centering spring built into the steering linkage or axle assembly — not within the cylinder itself. The spring provides a return-to-centre force that automatically steers the wheels toward straight-ahead when hydraulic pressure is removed. Some designs use a second, mechanically coupled cylinder on the opposite side of the axle as the return mechanism — effectively two single-acting cylinders working in opposition.

Single-acting steering cylinders are simpler to manufacture and lower in cost, but they have a fundamental limitation: the return force available (from the centering spring or mechanical linkage) is not hydraulically controlled and cannot be proportionally modulated. This produces steering that feels different in each direction — active hydraulic assist in one direction, mechanical spring return in the other — which modern operators and designers find unsatisfactory for precision warehouse manoeuvring.

How Double-Acting Forklift Steering Cylinders Work

A double-acting cylinder accepts hydraulic pressure on both sides of the piston. The orbitrol (hydrostatic steering unit) directs pressurised fluid to the cap-end port to extend the rod (steer left) or to the rod-end port to retract the rod under hydraulic power (steer right). In both directions, the force applied to the steering linkage is hydraulically generated and proportional to system pressure, producing symmetrical, consistent steering feel and response in both turning directions.

This symmetrical response is the primary operational advantage of the double-acting configuration. In a busy warehouse or port environment, a forklift must turn left and right with equal precision, speed, and effort — the operator must not have to compensate for directional asymmetry in steering response. Double-acting cylinders deliver this symmetry reliably, which is why they have become the standard for virtually all modern counterbalance, reach truck, and VNA forklift steering systems.

Double-acting cylinders also provide a natural lock-hold capability: with both ports blocked by the closed steering control valve, fluid is trapped in both chambers and the cylinder holds its position without the rear wheels drifting back from their steered angle. This is important for forklifts that must hold a specific steering angle while stationary — for example, during a precise lateral positioning manoeuvre in a rack aisle.

Which Forklift Types Use Which Configuration?

How to Confirm the Configuration of Your Machine Before Ordering

The quickest confirmation method is to count the hydraulic hose connections on the existing steering cylinder. A single-acting cylinder has one hydraulic hose connection (one port); a double-acting cylinder has two hydraulic hose connections (two ports — one at the cap end and one at the rod end). This visual check takes thirty seconds and provides definitive confirmation of the cylinder type installed.

A secondary confirmation method is to note the steering circuit’s return hose routing: in a double-acting system, return oil from the cylinder flows back to the reservoir through the orbitrol unit when the opposite port is pressurised — there is no separate return line from the cylinder. In a single-acting system, the exhaust side of the cylinder does have a return path (either an open-to-atmosphere port fitted with a breather, or a return line connecting back to the reservoir through a control valve).

When ordering a replacement forklift steering cylinder, always specify whether single-acting or double-acting is required alongside the bore diameter, stroke, and mounting dimensions. Supplying the wrong cylinder type — even one that fits the mounting points perfectly — will result in a non-functional steering system. For facilities managing mixed indoor and outdoor equipment including agricultural attachments, additional hydraulic compatibility guidance for outdoor implements is available at hay-balers.com.

Articulated Forklifts: A Special Case

Articulated forklifts — widely used in very narrow aisle (VNA) applications — steer by physically pivoting the front and rear chassis sections relative to each other at a central hinge joint, rather than by turning individual wheel knuckles. This articulation is driven by a pair of double-acting hydraulic cylinders mounted symmetrically on either side of the articulation joint, working in opposition: when one cylinder extends, the other retracts, pivoting the chassis sections in opposite directions.

These articulation cylinders are categorically double-acting — the articulation must be actively driven in both directions with equal hydraulic force. They are typically larger bore (70–100 mm) and shorter stroke than axle-steering cylinders, and are designed with specific rod diameter-to-bore ratios that account for the compression loading on the retraction stroke as the cylinder pushes the heavy chassis sections through the articulation arc.