The Ultimate Guide to Dump Trailer Hydraulic Cylinders

By: Matthew Polito | JTI Inc.

Hydraulic cylinders are the heart of any dump trailer, powering the lifting and lowering of the dump bed for easy dumping of materials. The service team and I have put together this comprehensive guide to help you understand, maintain, and optimize your dump trailer hydraulic cylinders. Whether you’re a seasoned operator or new to the industry, this guide has everything you need.

What Are Dump Trailer Hydraulic Cylinders?

Dump trailer hydraulic cylinders convert hydraulic pressure into linear motion to lift and lower the trailer bed. They consist of a piston, rod, and cylinder housing, working together to move heavy loads efficiently.

Cylinders come in two main types:

• Single-acting: Extends with hydraulic pressure, lowers by gravity. These are also called “power up/gravity down”, gravity down or power-up only cylinders.
• Double-acting: Uses hydraulic pressure to both extend and retract, offering more control. Sometimes also called DA cylinders, pressure up/pressure down, two-way cylinders and double acting rams.

• Scissor hoists are another type of lifting mechanism. Technically those also use hydraulic cylinders as part of the lifting mechanism, integrated with the scissor hoist, but these are considered separate from “direct push” cylinder hoists as mentioned above. Usually the cylinders are single-acting.

Understanding the capacity and type of cylinder is critical to safely handling your trailer’s load. JTI Trailers recommends selecting cylinders that match your trailer’s size and job requirements to ensure smooth operation.

Choosing the Right Hydraulic Cylinder

Choosing the right cylinder is essential for performance and safety. We advise considering:

• Trailer size and weight: The cylinder must handle a fully loaded dump bed. Check the cylinders’ load capacity.
• Material type: Different materials (sand, gravel, rocks) require different lifting force.
• Job requirements: Some jobs need faster dumping; others need precise control.

Other options include telescopic cylinders, which allow a higher dump angle while keeping the cylinder compact. Our team at JTI Inc. can help you determine the best cylinder for your specific trailer and job site needs.

If you know the type of material you’ll be moving, you can use this table of approximate weights as a guide to determine how much of the material your trailer’s axles and hydraulics can handle. 

Table of Approximate Material Weights by Cubic Yard

This table presents approximate weight of specific volumes of various materials--asphalt, concrete, rock, gravel, sand, etc. These are estimations--to get a better idea of what your load will weigh, consult the documentation (if available) with the material you're picking up. 

Table of Approximate Volumes of Common Dump Trailer Sizes

The table presents volumes by cubic yard and cubic foot. Table created by JTI Trailers.

(Open print-friendly PDF of both tables here.)

Single Cylinder vs Dual Cylinder?

You will also likely need to choose between dual cylinder and single cylinder lifts for your dump trailer. Both have pros and cons, and which will work better for you depends on your application.

A single telescoping cylinder provides strong initial lifting power and usually allows for a higher dump angle, which helps dense material slide out more cleanly. For this reason, it’s considered the more premium option, and usually costs a bit more. It also has fewer moving parts and weighs less than dual-ram systems. However, telescopic cylinders are more expensive to repair, can be slower to cycle, and offer less side-to-side stability when dumping on uneven ground. Single cylinder can also be more prone to the bed flexing if your load is uneven, shifting or you’re not on level ground.

A dual-cylinder (dual-ram) setup is more stable during dumping and often lifts faster because the load is shared between two cylinders. These systems are also cheaper to repair or replace, making them popular for general-purpose hauling. Their drawbacks are lower initial lifting leverage, a reduced maximum dump angle, and more moving parts that can wear over time.

Trailer GVWR/Carrying Capacity

 If you load the dump trailer past the capacity of the hydraulic cylinders but you don’t try to use the cylinders, and the dump bed stays down, in theory you can load more on the trailer. This would be if you’re planning to manually unload a load rather than dump it.

This isn’t recommended because this can put stress on cylinder mounts or frame crossmembers, even if you don’t try to lift the load. (Especially if the load is not centered/distributed in the bed.)

However, it’s also good to keep the trailer’s GVWR in mind on the off chance you find yourself in this situation.

Maintenance Tips

Regular maintenance extends the life of hydraulic cylinders and prevents costly repairs. JTI Inc. recommends the following:

• Inspect for leaks, worn seals, and damaged hoses
• Check hydraulic fluid levels and quality
• Lubricate moving parts to prevent wear
• Replace O-rings and seals when necessary

Our Hydraulic Cylinder Maintenance Checklist

Use this checklist to keep your dump trailer hydraulic cylinders in top condition:

Daily or before each use:

1. Visual Inspection: Check the cylinder, rod, and connections for cracks, dents, or corrosion.
2. Safety Check: Ensure all safety devices, locks, and guards are functioning correctly. (Crucial for preventing accidents)

Weekly

3. Hydraulic Fluid: Ensure proper level and clean fluid; replace if dirty or contaminated. (full replacement per manufacturer schedule, usually 1-2 years or about 2000 to 3000 hours)
4. Hoses and Fittings: Look for leaks, cracks, or loose connections. Replace any damaged hoses promptly.
5. Cylinder Operation: Extend and retract the cylinder fully to ensure smooth, consistent movement. Listen for unusual noises or binding.

Monthly

6. Seals and O-Rings: Inspect for wear or leaks; replace immediately if damaged. (Inspect seals and O-rings immediately if a leak is observed!)
7. Lubrication: Apply appropriate grease to moving parts as recommended by the manufacturer. Monthly or per manufacturer recommendation.
8. Pressure Check: Verify hydraulic system pressure is within manufacturer specifications. Monthly or after repairs/adjustments.

Quarterly (or after repairs or major service)

9. Load Test: Lift a standard load to ensure the cylinder performs efficiently.