Whether Power-Steerings

Preamble
Until late ‘90s, Power Steering per se’ was not provided by the carmakers as an OE fitment, at least in their entry-level hatch’s and sedan’s. But slowly things began to change when Hyundai first gave its option in their Santro.

Others naturally followed suit, with Maruti being the first to come out with ‘Electronic’ Power Steering in their smaller cars like the Alto and ‘Hydraulic’ ones in cars like Esteem and Baleno. So here’s an attempt to distinguish between the two systems and their pros and con’s…

A ‘Power-Steering’ is a ‘System’ which minimises the effort required to turn the Steering Wheel of a Car - which becomes more and more as the Cars get heavier and is worst during slow parking manoeuvres. Today they’re basically of two types – ‘Electronic’ and ‘Hydraulic’. Both eventually draw power from the engine - of the order of 3-5% - unlike power brakes.

The degree of ‘power-assist’ is designed to taper off as the car’s road speed increases, to maintain that ‘road feel’ at its steering and is, therefore, it’s designed to be max at standstill. It naturally comes at a price and then becomes another system in the Car to maintain - with attendant costs and vulnerability to failures - like any of its other systems.

An ‘EPS’ is relatively more ‘power-efficient’ than an ‘HPS’ and having lesser moving parts with no high-pressure hydraulics, it’s also less prone to breakdowns and maintenance. However, the flip side of it is that it requires a higher Capacity Battery/Alternator - especially for heavier Cars - thus indirectly adding to the overall cost of the System

On the other hand, an HPS runs off the engine directly. Eventually, both draw their power from the Engine only - which is the sole ‘prime mover on-board’. While HPS’ have been around since WW-II, EPS’ are < 10 yrs old and have yet to reach their full development, by way of providing that ‘feel of the road’ as compared to an EPS.

Here’s a real life QnA:

Question
For a car having low curb weight like Alto, Spark or Santro, is it wise to take a car without power steering? Does it affect the driving comfort significantly? Some people say that power steering makes a car more prone to accidents at high speeds.

Answer
For all practical purposes, cars tipping around 700-750 kgs can do w/o power steering. However, with increasing urban congestion leading to b2b parking and not to mention sissiness amongst men and women, power steering even for such cars is being looked upon more as a necessity than luxury.

As regards PS-Cars being prone to accidents at high speeds, it’s more of a myth since both the electronic and hydraulic ones are ’speed sensitive’, where the degree of ‘power assist’ is designed to go down with road speed. In fact the EPS guys claim that above 40 kph, the ‘degree of assist’ is zero i.e. revert to full manual.

On the other hand, with HPS, coz the system is always pressurised from both sides of the front/steering wheels, it infact resists sudden/involuntary direction changes at high speeds, to the extent that small unbalance in the steering wheels also doesn’t immediately result in a ‘wobble’, even at high speeds.