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HIAMS in the U.S.A.

Steering System

                                [Image] Brake System

Electronically controlled steering was initially limited to speed sensitive power steering systems. There are two types of power steering systems: electric power steering systems and hydraulic power steering systems. Currently hydraulic power steering systems are widely used, but electric power steering systems are rapidly coming into use, primarily in small passenger vehicles. EPS (electric power steering system) designed for small passenger vehicles that are currently mass produced. It conveys the motor torque to the steering gear from the pinion shaft through the reduction gear mechanism.

Motorized hydraulic power steering system: NHEPS (New Hybrid Electric Power Steering)

  • Hydraulic assist
    Greater reduction ratio than with gears
  • 12V power supply
    Since large reduction ratio possible, DC-DC converter for voltage step-up is not needed
  • Small cylinder diameter
    Motor does not need to be mounted on rack, since a large reduction ratio is obtained

Image:Steering Image:Steering

NHEPS is a motor-driven hydraulic power steering system designed to assist the driver in steering by applying direct pressure to the hydraulic cylinder through the motorized driving of the two-way trochoidal pump. NHEPS has the advantage of excellent vehicle-mountability since its power pack consisting of a pump and motor can be installed in a vehicle via piping independently of the hydraulic cylinder.

Electric Power Steering Systems

Features & Benefits

The pinion assist type electric power steering systems Hitachi Automotive Systems Americas, Inc. is currently mass-producing consist of:

  • High output and high-performance steering rack thrust up to 15 KN
  • Increasingly advanced components
  • Electronically-controlled and electrically-driven
  • High precision and highly reliable mechnics
  • A torque sensor that detects steering force
  • An electronic High precision and highly reliable mechanics
  • A torque sensor that detects steering forcesist force to a pinion shaft through a reduction gear mechanism
  • A rack and pinion type steering gear


The electronic control unit controls speed sensitive power steering systems by processing signals indicating the vehicle speed and the rotation of the engine. In addition, the torque limiter is positioned between the plastic gear in the reduction gear mechanism and the pinion shaft, and this protects the plastic gear from road surface pressure.

Belt Drive EPS System (BEPS)


Hitachi Automotive Systems Americas, Inc. Belt Drive Electric Power Steering System with enhanced steering feel and ISO 26262 ASIL-D compliant design.

Features & Benefits

  • Advanced safety with Limp Home and ISO 26262 ASIL-D compliant design
  • High reliability due to elimination of mechanical relays & ribbon cables
  • Enhanced steering feel is achieved by high accuracy rack, ball screw, pinion gear and ball screw grade control, all made in-house by Hitachi Automotive Systems Americas, Inc.
  • Full development capability from control logic to system development.
  • Torque Sensor: Non-contact Hall effect
    Digital communication
  • Absolute Steering Angle Sensor: Twin Gear with non-contact GMR plus Motor Position Sensor
    Redundant and Digital communication
  • Limp Home function is realized by the addition of redundant sensors


VDP and e-VDP for power steering


VDP and e-VDP for power steering to realize fuel economy improvement .This pump type has been developed to assist the automotive industry in reducing the fuel consumption and CO2 emissions particularly of upper mid-size and luxury cars to Large Trucks. Variable Displacement Pump makes a significant contribution to reducing the energy consumption of hydraulic steering systems and is characterized by a variable flow rate. The adjustable curve ring enables the control of the geometric flow rate depending on the speed. So the pump supplies always based on the required characteristic curve of the supply rate.

Features & Benefits

  • Fuel consumption can be improved
  • System oil temperature can be reduced allowing the cooling pipe to be simplified or eliminated
  • Discharge flow rate can be electronically controlled corresponding to vehicle parameters, leading to optimized steering effort (e-VDP)
  • Simple replacement of conventional pump due to standardized fixing
  • Reduced power consumption
  • Reduction of CO2 emissions


VDP is an oil pump for power steering used to achieve energy savings by eliminating a pump’s excessive operation as well as reducing driving torque by variably-controlling the displacement automatically corresponding to the pump speed.
e-VDP achieves even greater energy saving by electronically-controlling the discharge flow rate in accordance with certain vehicle parameters (vehicle speed, steering angle speed, etc.) in order to improve fuel economy and reduce CO2 emission.