“The Australian Motorist's” Advocacy of Producer Gas Upheld

Exhaustive Tests Prove Its Value to Australians

An article from 'The Australian Motorist', 1st April, 1930. Courtesy of Brendan Kinsella.

The following report contains information regarding the equipment and tests of a two-ton Guy lorry equipped with a Tulloch-Reading producer-gas plant, together with particulars of its operation under service conditions. The tests were conducted by the Development and Migration Commission Committee on Mechanical Transport.

For a number of years the development of producer gas plants has progressed, but a heavy Customs duty prevented producer gas plants being considered in Australia. Mr. Goode, representing Guy Lorries, introduced a vehicle so fitted, but the tariff was a block to its commercial adoption.

The "Australian Motorist" had advocated the use of producer gas, and set to work to get the tariff barrier removed. Opening up negotiations with Mr. Bruce, and supporting the plea with information obtained from overseas, the duty was removed, and the use of producer plants for heavy vehicle operation became practicable.

The Development and Migration Commission showed keen interest, and the Guy lorry, fitted with the producer, was ultimately purchased and put into operation by the Postal Department.

Where petrol is high in cost, due to transport, and where timber is available, fuel can be simply and cheaply obtained by making charcoal. Charcoal production is one of the world's oldest industries, and anyone with normal intelligence and a simple outfit can produce it.

The Guy producer plant on the Guy lorry attracted much attention. Photo shows the producer.

It will be remembered that the "Australian Motorist" advocacy of power alcohol was considered a journalistic dream, but road tests carried out by this journal were so convincing that public interest was aroused, and today large quantities are being produced in Queensland and distributed by the Shell Company.

The report on producer gas from the D. and M. Commission, which is as under, with a slight abbreviation, has been received from the secretary, Mr. Moorhouse:

4. Description of the Guy Lorry

In view of the fact that a definite loss of power is experienced in the use of producer gas as a fuel for motor vehicles, even when the engine is equipped with a higher compression head, the manufacturers, in designing a two ton producer gas model, employed the engine used in their three ton petrol vehicle.

Details of the lorry and engine are as follows:

The Guy two ton lorry chassis fitted with Tulloch-Reading gas producer plant follows the accepted practice for petrol-driven vehicles, and is identical with the firm's petrol two ton lorry except in regard to the producer and fittings incidental thereto, that the engine is, with the except of details mentioned later, the same as that fitted to the three ton lorry.

[Then follows a description of chassis, etc., which is of orthodox type. - Ed. "A.M."]

5. Description of the Tulloch-Reading Producer Gas Equipment

The following is a description of the Tulloch-Reading producer gas plant:

No Interference with Load

The fuel is carried in a hopper incorporated in the structure of the canopy, whilst the gas cleansing plant is carried well out of the way, the scrubbers at the rear end of the chassis and a centrifugal dust extractor under the off-side of the body, behind the driver's cab. The blower is mounted just forward of the dashboard, on the near side, where it is convenient to operate, but does not interfere with engine accessibility. The whole of the body space is therefore available for the load, and, whilst all parts of the producer plant are easily reached, the accessibility of the engine and transmission does not appear to have suffered.

A Large Fuel Valve

The fuel is fed by gravity from the hopper into a bunker above the valve. The latter contains a hollow plug (or barrel), which is slowly rotated by ratchet gear, so that an aperture on the side periodically comes uppermost, and the barrel is filled. Further rotation brings the aperture to the bottom, releasing the fuel down a vertical chute to the fire chamber. When the aperture is closing at the top the sharp edges cut through any pieces of fuel that may be caught. The barrel is tapered and held on its seating by a simple hinged spring clamp released by withdrawing a cotter pin. The smaller end of the barrel is slotted to engage with the driving member, worked by the ratchet gear; it is thus only necessary to release the retaining spring to extract it.

A neat device is incorporated in the ratchet gear that works the fuel valve. The pawl is retained in engagement by a spring, which is utilised also to keep it out of engagement when raised; thus, when approaching the end of a journey, the driver has only a raise the pawl, when the fuel supply ceases, and he runs home on that already in the generator. By experience the driver can gauge fairly accurately when to shut off the fuel.

Actuating Mechanism

A distinctive feature of the Tulloch-Reading Guy system is that the fuel regulating valves, the rocking camshaft, which continually agitates the fire bars, and the water pump are all continually worked from the engine by a very simple mechanism. A small housing at the rear end of the engine crankcase contains a worm wheel with which is engaged a worm on the end of the camshaft, the gear reduction being 80 to 1. On the worm wheel shaft is a crank connected by a rod to a lever fitted to a short horizontal shaft mounted below the driver's seat, and to the right of the generator. Rotation of the crank causes the shaft to rock, and, by a second lever on the shaft, the motion is transmitted for working the fuel valve and fire bar camshaft.

Water Supply to Vaporiser

Hand mechanism is provided for working the pump independently temporarily to increase the water supply when required. The pump delivers into a glass sight-feed vessel, which may be placed in any position that enables the driver to see if the pump is working properly. The outlet from the vessel is fitted with a jet having a restricted orifice, so that the water is supplied to the vaporiser at a slight pressure, and in a constant stream. The water from the main supply tank does not pass through the pump, but through a filter and ball valve into a chamber, from which connection is made both to the pump and the sight feed vessel. As the capacity of the pipe leading from this chamber to the pump is greater than the quantity displaced at each pump stroke, a clean water delivery is maintained, for the water in the pump, unavoidably contaminated with oil, merely surges to and fro in the pipe, propelling the clean water that passes through the filter and ball valve. Thus the sight feed vessel inlets and outlets are kept clean.

Thermostatic Air and Steam Control

The function of the vaporiser is to supply hot air and steam to the underside of the fire. Automatic regulation of the air and steam supply is obtained by a thermostatic device. A length of copper strip within the air and steam supply pipe has its ends so secured that it is slightly buckled. From the centre of the strip connection is made to a short arm of a bell crank lever, and to the end of a long arm is connected a vertical rod, the upper end of which bears against the underside of a hinged lid, closing an outlet at the upper end of the pipe to the atmosphere. Thus when the temperature within the pipe rises above a certain limit, the copper strip expands, and, through the medium of the bell crank and vertical rod, lifts the hinged lid and admits cold air. The length of the rod is adjustable, so that the point at which the lid opens can be advanced or delayed, whilst the position of the rod in relation to the hinge can also be adjusted to vary the degree of opening. The thermostatic device can, therefore, be set to suit any working conditions.

Petrol is used for starting up, and an ingenious type of valve is fitted to the intake pipe to control the admission of petrol or producer gas mixtures either separately or together. The valve is of the tapered barrel type, held on its seating by hinged spring clamps, like that used for the fuel control valve, so that jamming is prevented. The barrel is formed with a passage, which, in the vertical position, is a continuation of the intake pipe, though sealing the petrol mixture pipe from the carburettor. One side of this passage, however, is cut away, so that when the barrel is turned to cut off the producer gas, petrol mixture can be drawn into the engine. Within the barrel is an ordinary butterfly valve mounted on a spindle, with level so interconnected with the carburettor butterfly valve that both are controlled by the same accelerator pedals. Movements of the barrel do not affect the butterfly valve inside, consequently the producer gas or petrol mixture control is independent from the accelerator pedal control, which regulates only the quantity of either mixture supplied to the engine.

The gas, after leaving the furnace, passes to a cyclone scrubber, where most of the dust is deposited, and thence through a light gauge drawn-steel pipeline, zinc treated, to a series of four tubular sheet steel scrubbers situated transversely at the rear of the chassis. These scrubbers, which are provided with easily detachable ends, are divided by baffle plates into compartments, which are filled with wood wool. From the scrubbers the gas passes to the special conical valve (referred to in the previous paragraph), placed between the carburettor and inlet manifold, which admits the fuel air mixture and controls the ratio of the gas-air to petrol-air mixture.

The engine is started on petrol, and changed over as soon as the gas generated in the producer is of the required value.

6. Tests

In May, 1928, one of these vehicles was made available to the producer gas sub-committee by Messrs. Guy Motors Ltd. for observation and test.

The lorry was operated under service conditions by the Postmaster General's Department, and, during the month, a total distance of 842 miles was travelled, using 2023 lb. of charcoal, 35 gallons of water, and 12 gallons of petrol. This represents a consumption of 2.4 lb. of charcoal per mile; but, as a considerable amount of time was spent in idling and empty running in the city and suburbs, this cannot be regarded as an average consumption for the vehicle when operating on the type of transport for which it is most suitable.

A good indication of the performance is given by a trip to Mt. Dandenong on June 20, when members of the sub-committee travelled with the lorry in order to observe its behaviour.

The lorry was loaded with scrap iron, and, including passengers, the total load was 2 tons 11 cwt. The tare of the lorry being 3 tons 3 cwt., the gross load was 5 tons 14 cwt. From the Postal Garage to the Fiveways, Mt. Dandenong North, a distance of 26.5 miles, the total rise is 1,460 feet. This distance was travelled in 2 hours and 18 minutes, the average speed being 11.5 miles per hour, and the amount of charcoal consumed 81 lb. The return trip was made in 1 hour 37 minutes, at an average speed of 15.9 miles per hour, and for a fuel consumption of 71.5 lb. of charcoal. The average speed over all was 13.5 miles per hour, and the amount of fuel used was 152.5 lb. of charcoal, two gallons 'of water, and a quarter of a gallon of petrol was used for starting purposes only.

This represents a fuel consumption of 1.13 lb. of charcoal per net ton mile, and a consumption of 0.13 lb. of water per lb. of charcoal.

The hill at the end of the run has a length of 3.4 miles and an average grade of 1 in 22.4 (maximum, 1 in 20), and the average speed in third gear at this point was 7 miles per hour, with a maximum speed on a 1 in 20 grade of 7.6 miles per hour.

Assuming 56 lb. per ton as the resistance to motion, the horse power required to maintain this performance would be 19.4. If the losses in the gearbox, etc., be assumed as 6 percent., the brake horse power of the engine would then be 20.6.

Considering the large amount of climbing encountered on the journey, the machine can be regarded as having performed very satisfactorily.

The following table gives a summary of some individual results obtained by the sub-committee with a two-ton Guy lorry while under trial for one month:


A. Trip to Traralgon, May, 1928

During this run demonstrations of the machine were given at all towns en route to Traralgon; this caused a larger petrol consumption than normal, due to frequent starting of the engine.

Of the 480 lb. of charcoal used on the whole trip of 209 miles, 420 lb. was obtained from Queensland, and 60 lb. was English charcoal (believed to have been made from W.A. kauri timber), which had been supplied with the vehicle.

The Queensland charcoal had been obtained from iron bark timber at Darra. It was ordinary commercial ungraded charcoal, the analysis of which had revealed 3.5 percent of ash containing a large percentage of calcium carbonate, which it was considered would, to a large extent, prevent the fusion of the ash and modify difficulties due to clinkering. Clinker formed during the run, however, amounted to 19.5 oz., possibly due to the presence of foreign matter in the charcoal. No operating trouble was experienced with the clinker owing to the action of the rocking grate, which prevented the clinker from clogging up the firebars.

During the run two fuel blockages were caused by large lumps of charcoal choking the lead from the hopper to the fuel valve. Otherwise no fault was found with the running of the machine.

B. Trip to Bendigo, May, 1928

Demonstrations during the run again accounted for a higher petrol consumption than would otherwise have occurred.

On the outwards run 260 lb. of Western Australian pit-burnt Jarrah charcoal, obtained from Chidlow, near Perth, was consumed. No clinker was formed with this charcoal, the analysis of which gave an ash residue of 0.12 percent, having an alkalinity of 5 percent of the ash content, calculated as potassium carbonate, K2CO3.

On the return journey, 240 lb. of Victorian grey box charcoal, obtained at Bendigo, was used. On arrival at Melbourne, it was found that 42 oz. of soft clinker had formed in the furnace of the producer.

C. Trip to Geelong, June 12, 1928

Tasmanian charcoal, obtained from blue gum timber, at Neika, near Hobart, was used on this trip. The fuel contained a considerable amount of incompletely charred wood, which the rotary feed valve was unable to shear through; this caused stoppages and loss of time, especially on the return journey.

The fuel also proved to contain a considerable amount of foreign matter and as a result large quantities of clinker were formed, but trouble was averted by the rocking action of the grate.

An analysis of this charcoal gave an ash residue of 0.32 percent, having an alkalinity of 28 percent of the ash content calculated as potassium carbonate, K2CO3.

D. Trip to Geelong, June 15, 1928

On this trip Tasmanian charcoal was again used, and, as in the previous trip, large quantities of clinker were formed, without serious detriment to the operating efficiency of the plant.

On the return journey the vehicle, although operating on defective fuel, satisfactorily carried 50 percent, excess of its classified load capacity.

The greater mileage of the total trip was due to the vehicle being diverted from the direct route in order to deliver stores at another depot.

E. Trip to Mount Dandenong, June 20, 1928

On the trip to Mount Dandenong, previously referred to, the fuel used on the outwards run was retorted charcoal obtained from Mr. Holmquist, at Gisborne, Victoria, and that used on the return journey was charcoal imported to Australia with the vehicle, and believed to have been made from Western Australian kauri timber.

On December 11, 1928, a second run to Mount Dandenong was observed by the sub-committee in order to test the effect of certain minor alterations, which had been made by the makers. The engine started easily from cold, and changed over to gas eight minutes after starting to prepare the fire. The lorry behaved very well, and made a more satisfactory showing than on the previous occasion. Its performance on the long hill at the end, obtained from the two tests:

7. Operation Under Service Conditions

In May, 1929, the vehicle was taken over by the Postmaster-General's Department (Transport Section), and has since formed one of the regular units of the Melbourne fleet.

During the period from June 17 to November 15, 1929, the lorry ran 1943 miles, being chiefly used for city and suburban work, carrying heavy engineering stores. At times fairly long periods of waiting were involved at wharves or store yards, and during these times the fire was necessarily kept alight, with the result that the fuel consumption per mile was heavier than would have been the case on long runs.

The lorry has given satisfactory service in spite of the fact that producer gas vehicles are more suited to long, continuous hauls than to short runs in heavy traffic. In traffic it is difficult to distinguish the performance of this vehicle from that of a petrol-engined lorry, except for the fact that the idling speed on producer gas is somewhat high.

During one period of service, a test was made of "carbonite" (pelleted charcoal), instead of the ordinary commercial charcoal, but it was found that these very hard pellets were liable to stop the rotation of the rotary fuel admission valve. It was also found that in using carbonite, very bad clinker was formed on the grate, which was exceedingly difficult to chip off wh2n cold. While this form of charcoal may give excellent results in down-draught producers, and is in many ways preferable to ordinary charcoal owing to its greater cleanliness and decreased bulk, it is not suitable for producer plants of the updraught type, such as the Tulloch-Reading.

At another period considerable trouble was experienced through the fuel containing incompletely charred wood, which caused the rotary feed valve to jamb. Trouble was also experienced owing to badly graded charcoal causing blockage in the feed pipe.

In the following table, a summary is given of the results obtained with the lorry during the period under review:

In the above table the price of charcoal has been taken at £3 per ton, this figure being based on quotations and estimates obtained from recognised charcoal suppliers.

It is clear that the relative economy of producer gas vehicles compared with petrol vehicles depends largely upon the price of charcoal. This aspect of the investigation will be fully dealt with in the sub-committee's fourth interim report, which will be submitted shortly.

It is estimated that the fuel consumption of a petrol-driven vehicle doing similar work would be 7 mpg., which, at 1/9 per gallon, gives a fuel cost of 3d. per mile. It may, therefore, be concluded that the fuel costs for the Guy lorry, equipped with a producer gas plant, are approximately one-third of those of a petrol lorry of similar capacity.

The time required to prepare the vehicle for the road, including cleaning the scrubbers and lighting the generator, is approximately 30 minutes, compared with an average time of 20 minutes for a similar capacity petrol vehicle.

8. Maintenance, Repairs and Depreciation

On January 10, 1930, the cylinder heads were removed, and an examination made of the cylinders and valves. The deposit on the cylinder heads and valves was light, dry and brittle. The deposit was not excessive, and did not exceed that to be expected in an average good petrol lorry engine operated for a similar period.

A sample of the deposit was submitted to the Commonwealth Analyst, who reported upon its analysis as follows:


The low percentage of silicious mineral matter indicates that the scrubbing apparatus was operating efficiently. The amount of iron present in the ash is normal to a new engine that is being run in.

Taken on the whole, the sample of deposit could be regarded as comparable with that in a good average petrol engine operated under similar conditions.

The pistons were not withdrawn, but very little movement could be detected by rocking them; variation in the bore of the cylinders did not exceed two-thousandths of one inch, indicating that there had been very little, if any, wear in this direction. The exhaust valves were of a decided red colour, and the inlet valves the usual grey colour.

Generally speaking, the examination of the engine failed to disclose any variation in condition other than would be expected from the examination of a good type of petrol engine operated for a like period and under similar conditions.

The Tulloch-Reading producer gas equipment was not dismantled, but a general inspection of the plant revealed no undue wear or need for repair.

Minor repairs carried out from time to time since the lorry entered the service of the Postmaster-General's Department did not include any part of the producer gas plant, with the exception of the conical change-over valve, which was not gastight, and was reground. 

In consideration of these facts, it appears that the maintenance charges are not likely to be heavier than with a similar type of petrol lorry.

9. Charcoal

The sub-committee desires to lay particular emphasis upon the importance of the charcoal being retort burnt, and absolutely free from earth, stone or any other foreign matter. The introduction of only a very small amount of this foreign matter is likely to cause trouble from clinker formation, and although the rocking grate of the Tulloch-Reading producer gas plant tends to prevent the clinker adhering to the firebars, the presence of clinker must detract from the efficiency of the plant. It is, therefore, recommended that charcoal for producer gas motor vehicles should be procured from timber entirely free from earthy or other foreign matter, and that great care should be exercised in the bagging of the charcoal to avoid the inclusion of this foreign matter at that stage of charcoal production.

10. Conclusions

The sub-committee is of opinion that the Guy motor vehicle, equipped with a Tulloch-Reading producer gas plant, as tested, is an effective producer gas motor vehicle, capable of economical operation, provided the added first cost of the complete vehicle does not counteract the economy which undoubtedly can be effected in fuel costs.

Owing to the fact that the vehicle has only been operated under producer gas for a total distance of about 2,785 miles, it is not possible for the sub-committee to express an authoritative opinion regarding depreciation of the producer gas equipment; this can only be determined after prolonged use. It is, however, an important aspect of the economic use of producer gas plants for the propulsion of motor vehicles in Australia. The sub-committee strongly recommends that the vehicle now under review be used continuously as a producer gas motor vehicle, and its performance closely watched by the Postal Department, so that a true record of its durability and life can be obtained.

The sub-committee also recommends that, if possible, the vehicle be used on long-distance work for the department, so that it may be utilised under conditions most suited to the use of producer gas, and obtain as big a mileage aggregate as possible in the shortest time.

As a result of trials carried out with the Guy lorry equipped with a Tulloch-Reading producer gas plant, the sub-committee considers that the use of producer gas obtained from Australian charcoal does offer an economic and effective alternative fuel to petrol for commercial motor vehicles more especially in those parts of the country far removed from the seaboard, where imported liquid fuels are dear, but where waste wood for the production of charcoal may be plentiful and cheap.

This class of vehicle also offers attractions to farmers, who, by the expenditure of a small outlay on equipment, should be in a position to supply their own retorted fuel for their motor lorries.

11. Acknowledgments

The sub-committee desires to place on record its appreciation for the cooperative assistance rendered by the Postmaster-General's Department in keeping the sub-committee informed regarding the performance of the Guy lorry and facilitating observation of its operation when necessary.

The sub-committee also desires to refer appreciatively to the keen interest taken in the investigations by Mr. C. Florant, the driver of the vehicle, whose careful observation of the performance of the lorry has been of material assistance.

The Producer Gas Sub-committee of the Committee on Mechanical Transport:

Edward J. C. Rennie, Chairman
G. Baghel, Member.
C. K. Bromell, Member.
G. A. Cook, Member.
A. E. Dawkins, Member.
C. J. Kirkbride, Member.
Thomas E. Moorhouse, Secretary.

February 12th, 1930.

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