A SUGGESTION FOR A HYDRAULIC TRANSMISSION
Page 40
If you've noticed an error in this article please click here to report it so we can fix it.
THE article concerning the post-war importance of goods and passenger vehicles, by Mr. James Courtney, M.I.A.E., published in your journal some months ago, greatly interested me. Following this, I would like to take this opportunity of suggesting a design which might prove revolutionary.
In the past, nearly all makers of vehicles have adhered to almost the original layout, although this has been improved upon until it has reached a fairly high degree of efficiency, but the day is approaching when we should see no clutches, gearboxes, propeller shafts, live back axles and frictional drives.
Such an opinion may seem far-reaching, but so was Group Captain Whittle's new design for jet-propulsion aircraft; yet this is proving successful.
What I have in • mind is a fluid-pressure-operated driving gear in which the engine will .be connected to a gear-type master pump, whence the power will be conducted through four pressure conduits to driving pumps " of the eccentric type closely adjacent to the wheels, return conduits leading the fluid back to the main pump. For reversing purposes, there will be fitted in the pressure manifold from the main pump, rotary selector valves which would reverse the functions of the conduits, whilst for gearing up from zero to maximum there will be a further rotary valve mounted between the manifold and the hydraulic distributor. With this open no pressure would be transmitted; by closing it the load would be taken up. A braking action in either direction could also be obtained, valves for this purpose being mounted in the ports of the wheeldriving "pumps."
The valves for reverse and for relieving the pressure while braking would be operated by a combination of oil pressure from the engine and solenoids. Reverse would be controlled by a press button on the dash, whilst the pressure relief would operate with the movement of the brake pedal.
For the gearing-up valve, a small hydraulic system would be mounted under the steering wheel. The method would permit driving and braking on all wheels, the only major parts in frictional contact would be the two gears of the pressure pump and the fibre blades of, the driving pumps with their casings. With this system a better performance should be obtained from engines of low horse-power.
Reverting to other matters, my experience consists of operating seven vehicles, with the responsibility of maintaining them and carrying out any repairs. This work gives me justification for complaining of the ridiculous method of riveting to the chassis frame 'such components as spring and engine brackets, instead of employing high-tensile bolts and nuts.
I endorse previous complaints regarding cabs, whilst the layout of the electric wiring calls for extensive modification and protection.
The steering of heavy goods vehicles is often heavy to handle when they are fully loaded, and I would suggest an improved hydraulic form of steering.
.A3g Mr. Courtney states that the vehicle industry must
be kept up to date to meet the coming strong competition in the overseas markets. I agree that this is of vital importance, and it is the duty of all of those who are concerned to turn out a more efficient type of vehicle, which will embody the features of simplicity of design, low running costs and ease of maintenance.
Amersliam. GORDON LEE.
(For G. Lee Transport.)
[We do not wish to discourage ideas for better vehicles but we would certainly like to know if Mr. Lee or others interested in the subject of the hydraulic transmission, as suggested, have carried out any practical experiments. We have ourselves been acquainted with hydraulic transmission since 1908, and therefore, know si3ine of the problems and difficulties, amongst which are heating and frothing of the liquid employed, considerable frictional losses in fairly long pipe lines or conduits (as Mr. Lee prefers to call them), the weeping of joints under high pressure, etc. Another factor is that in many forms of suggested hydraulic transmissions there is really no equivalent to an infinite gear ratio, except by what is
virtually slip and, therefore, loss of energy. It would appear necessary to be able to control the output of the main pump or pumps at source, or enable the effective " blade " area of the driving " pumps" to be varied, in order to avoid such power loss—ED.]