A Hydraulic Cooling Unit (HCU) is designed to be quiet, lightweight, and compact to meet the needs of today's market demand. Wet kits (or wet line kits) are kits that are installed in trucks or agricultural equipment equipped with a Power Take Off (PTO).
A PTO takes energy from a power source, such as a running engine, and transmits it to an application, such as an attached device or separate machines.
These ventilation and cooling units have diverse applications, including:
- Chemical transportation
- Crude oil transportation
- CO2 delivery trucks
- Food transportation
- LP/bobtail gas transportation
- Maintenance trucks
- Water trucks
- Application and agricultural equipment
- Bulk feed trucks
- And vacuum trucks
Typically, the tank volume for the aforementioned applications is equal to 1-1/2 to 2 times the total flow of the pump. If you have a pump of 25 gpm (gallons per minute), the tank size will usually be between 38 to 50 gallons. Hydraulic oil weighs 7.3 pounds per gallon, and a 50-gallon steel tank has a dry weight of 157 pounds, plus 365 pounds of oil, which results in a total weight of 522 pounds. Tanks are designed for natural heat radiation. 
Figure 1. Hydraulic Cooling Unit AKG
In real-world applications, limited mounting areas, direct sunlight exposure, and poor air circulation can reduce heat dissipation. Direct sunlight can cause the tank to absorb heat, raising the oil temperature above a safe operating temperature.
Replacing the tank with a cooler can save fuel due to weight reduction and prolong the lifespan of hydraulic systems by keeping the oil cool and ventilated. Trucks equip many accessories, such as a boom or crane, and the truck's PTO activates the hydraulic pump for the wet kit.
Heat is generated in the hydraulic system, necessitating a large tank or a cooler block. Without adding an auxiliary heat exchanger, the temperature in a tank system will continuously rise with usage. There may be a lengthy downtime required to cool the oil, resulting in lost time.
The HCU is designed to fit into very confined spaces that can easily mount on the frame rail. The narrow profile is also designed for shaping and cooling for a variety of applications, such as:
- Chemicals
- Compressed gases
- Food grade
- Crude oil
- Vacuum pumps
- Hybrid drive
- Bulk feed trucks
- Liquid transportation
Note:
One of the useful advantages of wet kits is the significant weight reduction in your vehicle that allows you to carry more product. This unit not only cools hydraulic oil but also stores and filters the oil, eliminating the need for massive tanks that contain large amounts of oil:
- The HCU unit offers low sediment cooling with a finless design that provides optimal heat transfer for any given cooler size in the industry.
- The new rugged series coolers provide lower aerodynamic values while preserving the oil and hydraulic system.
- The durable HCU AKG coolers feature proprietary research and development, design, engineering, and testing both internally and externally.
- Automotive-approved noise-reducing foam
- Corrosion-resistant – stainless steel/aluminum construction with premium coating
- Vibration tested to MIL 810G standards – PSD tested
- Easy installation
- Noise level 85 d(B)A
- Our HCU unit offers competitive pricing and warehouse delivery through an exclusive distribution network.
A compensated flow with a constant pressure can power the hydraulic fan motor that automatically turns the fan on. This setup rotates the fan blade to the necessary RPM to maintain a constant oil temperature.
The electric fan motor option features a 12 VDC cooling fan that operates with a temperature control switch. This switch connects to the ignition power. When the ignition is on and the oil temperature reaches a specific temperature setting, the switch activates the fan.
When the oil temperature drops below the set temperature, the fan turns off. The hydraulic fan motor option can be equipped with a compensated flow control that automatically "turns on" the fan and rotates the fan blade to the necessary RPM to maintain a consistent oil temperature. This option is preset and piped from the factory. 
Figure 2. Operation of AKG Hydraulic Cooling Unit Oil Coolers
Fan Control in the Hydraulic Cooling Unit HCU:
The innovative 12 VDC brushless drive fans have a much longer lifespan. There are two options for fan control: 1- The fan controller can adjust the fan speed (airflow to the cooler) to regulate the oil temperature.
Similar to the hydraulic fan control. When the oil temperature is below the desired set point, the fan will not operate. 2- A temperature changes for the fan's on/off cycle when the oil temperature is below the desired set point; the fan will not operate.
Figure 2 provides a summary of the performance of each proposed fan drive. The HCU series can handle applications at temperatures and pressures up to 250 degrees Fahrenheit and 250 psi.
