Wet Kit Installation for a Live Bottom Trailer — Ames Hydraulics

Wet Kit Installation For A Live Bottom Trailer

A live bottom trailer is the highest hydraulic demand of any common trailer type. Where a walking floor moves in short strokes, a live bottom’s chain-drag or belt system runs continuously at high flow to move the entire load out of the trailer in one steady motion. That means a wet kit installation for a live bottom trailer needs a piston pump, a three-line system with case drain, and a larger tank than any other configuration. It is not a job for a general-shop wet kit install.

Our shop is in Ames, Iowa. Live-bottom trailers show up on grain haulers, mulch haulers, and aggregate operations, and we do wet kit installation for live bottom trailer applications on all the common Class 8 truck platforms — Peterbilt, Kenworth, Freightliner, Mack, International, and Volvo.

Why A Live Bottom Needs Three Lines

Standard two-line wet kits (pressure + return) work fine for gear-pump-driven trailers. But live-bottom trailers usually run piston pumps or high-flow hydraulic motors on the trailer, and piston pumps require a case drain — a third line that carries away internal leakage oil back to the truck’s tank. Without a case drain, the piston pump’s case pressure builds up and destroys the shaft seal within hours. Three-line wet kit installation is not optional for a piston-pump live-bottom trailer.

Piston Pump Selection On The Truck Side

The truck-side pump on a wet kit installation for a live bottom trailer is usually a Parker P30 or P50 piston pump at 30-50 gpm displacement, driven at 2500-3000 psi. Piston pumps handle the higher continuous-duty pressures better than gear pumps and give us the flow the live-bottom trailer requires. Piston pumps also cost more than gear pumps — expect $1,500-3,500 for the pump alone depending on displacement and model. That’s part of what makes live-bottom wet kits more expensive than dump or walking-floor installs.

Tank Sizing For Continuous High-Flow Duty

Live-bottom trailers run at high flow for 3-5 minutes per unload. That’s a lot of oil moving through the system. The tank has to hold enough to feed the pump continuously AND cool the returning oil before it’s pushed back through. A 50-60 gallon tank is the practical minimum for a live-bottom wet kit installation. Anything smaller runs hot and shortens pump life. We build steel tanks in-house at these sizes with proper baffling, sight gauges, breathers, and case-drain ports plumbed in.

Case Drain Routing

The case drain line runs from the trailer-side piston pump back to the truck’s tank at low pressure. The line must be sized correctly — too small and the pump’s case pressure builds up, too big and it becomes a routing headache. We use #10 or #12 hydraulic hose for case drain on most live-bottom installs. The case drain terminates at the tank, not at the return line, so returning case oil doesn’t restrict main return flow.

PTO And Transmission Match

Same rules as any wet kit install — PTO must match the truck’s transmission. Eaton Fuller, Allison, mDrive, DT12, PACCAR TX-12 — each has specific PTO options. The PTO must also spec the correct output RPM for the piston pump; piston pumps typically run in the 1500-1800 RPM range at rated flow, so PTO gear ratio and driveshaft RPM have to combine to hit that number at highway idle or engine cruise speed.

Oil Cooling Is Often Required

Live-bottom continuous-duty operation heats fluid faster than gear-pump systems, and we usually install an oil cooler in the return line for live-bottom wet kits. Either a plate-fin air-cooled cooler on the frame or a shell-and-tube heat exchanger tied to the engine cooling system. That adds $500-1,000 to the install but keeps the fluid below 180°F on the longest unload cycles.

Cost Ranges

Three-line wet kit installation for a live bottom trailer runs $6,500-$9,000 depending on pump and tank sizing. Add $500-1,000 for oil cooling. Add $500-1,500 for a custom-built tank if the truck needs a specific size or mount. Retrofits (correcting a prior bad install) add $500-2,500 depending on scope. Every job gets a written quote before we start.

Turnaround

A live-bottom wet kit installation is a one-to-two-week job in our shop. Piston pumps sometimes require longer lead times on parts, so we confirm parts availability before we quote timing.

Independent Scope

We are not a truck dealer. We do not do warranty work. If your truck is under warranty and something engine-related needs attention, go to the dealer network. If you need a wet kit installed for a live-bottom trailer and want it done right the first time by a shop that has installed piston-pump systems dozens of times, we’re the right stop.

Common Questions About A Wet Kit Installation For A Live Bottom

Why do I need three lines for a live bottom trailer? Piston pumps require a case drain — the third line back to the truck’s tank at low pressure. Without it, case pressure builds up inside the pump and destroys the shaft seal within hours.

Can I use a gear pump instead of piston for a wet kit installation for a live bottom? Some smaller live-bottom trailers can run gear pumps, but most modern live-bottom units are piston-driven. Verify with the trailer manufacturer or send us the model number and we’ll check.

How much does a wet kit installation for a live bottom cost? $6,500-$9,000 all-in for a three-line install. The piston pump alone accounts for $1,500-3,500 of that. Oil cooling adds $500-1,000.

Do you install oil coolers on live bottom wet kits? Yes, and we almost always recommend one. Continuous-duty operation heats fluid faster than gear-pump systems, and a return-line cooler extends pump life significantly.

Get A Quote

Call or text 515-292-2599. Tell us the truck model, transmission, live-bottom trailer make/model, and pump type on the trailer. We’ll ballpark the wet kit installation for the live bottom trailer over the phone and firm the quote when we see the truck.