Advanced Products

Model: OK4

OK4 Hydraulic Oil Cooler

The OK4 provides up to 115,000 Btu/h of heat rejection. This unit is perfect for any oil or glycol cooling needs in applications with medium to high cooling demand such as electronics cooling for hybrid transit busses or hydraulic oil cooling for large vehicles and equipment. The system can also be installed as a primary engine cooling unit for small vehicles and equipment. The OK4 features four variable-speed EMP fans with long-life brushless motors and full reversibility to keep the heat exchanger clean through years of harsh use.

The OK4 is available in 12V and 24V, pusher and puller models. Control strategy can be configured as temperature control, PWM or CAN control, or simple on/off. Temperature controlled OK4 models feature the EMP TMC system controller. Custom fan layouts are available upon request.

Front View
OK4 Chart

Features & Benefits

EMP Brushless Electric Fan

All OK4 coolers feature EMP fans. EMP's fans are brushless, controllable, reversible, and built from a cast aluminum shroud that can withstand even the harshest environments.


Type Specification Description
Max Heat Rejection Rate 115,000 Btu/h
Overal Package Weight (Without Fluid) 190 lbs.
Heat Exchanger Material Aluminum
Shroud Material Steel
Max Continuous Operating Temp 203° F
Min Continuous Operating Temp -40° F
Max Fluid Temp 212° F
Fan Configuration Push or Pull
Voltage 12 or 24 Volts
Max Current 100 Amps
Max Fan Speed 4000 RPM (14V)
4600 RPM (28V)
Max Continuous Operating Pressure 220 psi
SAE O-Ring Boss Port Size -16 (1 5/16"-12)
Maximum Fluid Flow Rate 22.5 GPM
Heat Exchanger Fluid Volume 3.8 Gal.
Control Inputs On/Off, CAN/J1939, PWM, or Thermistor
Fan Reversal Control Push Button, Timed, or Ignition On


Please click on the thumbnail below to view a larger version of the image.


Voltage Configuration
12V 24V Push Pull
Optional Approval Rating
UL-Approved CSA-Approved
On/Off PWM J1939 CAN Thermistor EMP-Link



Hydraulic Applications for Loaders

Downloads & Documents

The following documents are available for this product. Please feel free to download to obtain additional product information.

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