Selecting the right wet kit for a heavy truck

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Updated Jun 20, 2023
Purple International dump truck
The most common usage of wetline kits in medium- and heavy-duty trucks is to raise and lower dump bodies and trailers.

[This article was originally published in 2022 by Trucks, Parts, Service. It has been updated to include more timely information.]

An essential component for dump trailers and many other truck body and trailer applications, wetline kits are vital for many trucking operations. Also known as wet kits, wetline kits use power take-offs (PTO) to provide power to perform trailer or truck body functions.

Wet kits can be spec’d into new equipment by first-time owners, but they also have strong aftermarket demand by secondary truck owners who purchase trucks and intend to use them in a different duty cycle than their initial application.

When selling a wet kit to a customer, it is important that aftermarket providers understand the customer’s true intent for their truck to help them pick out the best kit available.

Wet kits for end dumps and dump trucks come as two-line or three-line systems, with the latter systems adding a return line hose. Most OE genuine and aftermarket wet kit manufacturers offer multiple kits per solution, and wet kits also can be built custom by hydraulic specialty service shops. Other kits include combo kits that enable a tractor to power multiple trailer systems, and side dump and bulk liquid system kits that require additonal componentry to power a system. 

Three-line wet kits offer several performance benefits over two-line options.

Muncie Power Products recommends three-line wet kits in nearly all applications due to their faster cycle times, reduction in pump failures and ability to keep the system temperature lower. The company notes three-line wet kits do “not raise the dump trailer faster” but do provide other benefits and a greater long-term value.

[RELATED: Proper PTO installation a valuable resource]

Two-line wet kits are often best in lower usage applications, such as occasional raising and lowering of a dump body or trailer. Two-line wet kits also function best when not left in neutral, Muncie adds, as excessive neutral use can increase performance temperatures and reduce system longevity.

When supporting a customer’s wet kit selection, Muncie advises to consider not only the application and duty cycle in which the kit will be used but also how long the purchaser intends to operate the system. Customers also should consider any future use, as spec'ing a tractor with one wet kit for one application but eventually using it another application can weaken its performance and life cycle. 

Customers running low boy trailers, working off-highway and/or consistently hauling loads exceeding standard GVWRs should still consider three-line wet kits even if they do not anticipate excessive kit use, manufacturers say. The third line in the kit exists to support not only prolonged use but also more extreme use and can maintain its peak performance level for a longer period.

Three-line wet kits also often come with longer warranty periods, reducing overall total cost of ownership (TCO) for truck owners committed to wet kit-required applications. Additionally, rebuilt or recycled two- and three-line wet kits have many of the same performance traits as new aftermarket components but with shorter life cycles and warranty options.

Finally, manufacturers note a customer seeking an immediate purchase to end a downtime event should be forewarned that purchasing a used kit may ultimately experience a higher TCO if they intend to keep the tractor for a substantial period of time.

Once installed, a properly selected and maintained wet kit can provide reliable performance for many years. Through simple conversations with customers about their work history and application intentions, sales professionals can ensure those performance benefits are achieved. 

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