Mechanized equipment for afforestation work in France1
Equipment planting operations
Subsoil tillage tools
Check list of planting equipment suggested for use by forest owners in France
1 Contributed by the Forest research and Experimental station, Direction générale des eaux et forêts, France.
A pamphlet has been widely distributed to forest owners in France explaining the advantages of the use of mechanized equipment in tree planting operations.
In the first place, the use of machines ensures good tillage of the soil and consequently a high percentage of success with the planted stock. Delay in the trees putting on growth which, at least for quick-growing species, can appreciably lower the return on the investment, is thus avoided. At the same time, it permits economy in outlay on nursery stock and seeds, the cost of which can be high for relatively scarce species or specially selected plants.
On some sites, where the climatic and soil conditions are particularly unfavorable, mechanization seems often to be the only method of guaranteeing success in afforestation.
Mechanization is also often a means of reducing costs. As against manual labor it has advantages in regard to soil preparation and also in the actual planting operations: quicker setting-out techniques; use of smaller (or younger) planting stock owing to a more thorough clearing of competing vegetation, and better conditions for initial growth.
The period suitable for carrying out planting work in both spring and autumn is always short. By finishing the work quicker with machines, the operator may keep within the optimum period and so ensure a higher percentage survival of plants.
Lastly, mechanization affords psychological and social advantages. The landowner considers that it offers a more spectacular and ' modern ' work effort. The operator feels he is doing more up-to-date work; young and capable workers are more easily attracted to forestry, and because of the increased output better salaries can be paid.
Special working conditions
Save in exceptional cases (nurseries or the planting of land where farming has been recently abandoned), forestry equipment has to be employed both in and outside the forest under conditions different from those under which farm machinery proper is used The latter can be utilized for forestry only in certain circumstances.
Machine manufacturers are thus faced with a new problem and the correct solution can come only from collaboration between them and the users, since each knows only one side of the question.
The main feature of work connected with tree planting is its diversity. There are always visible or hidden obstructions in the ground, and it is in relation to this peculiarity that the nature of the machines for planting has to be considered.
A first solution would be to have sturdy machines sufficiently high-powered to overcome practically all obstructions. Experience shows that in many cases this leads to the use of an engine power of over 100 horsepower and very heavy machines (10 to 20 tons) with a very high amortization, which in consequence, need to be intensively utilized, a practice that, with a few exceptions, is not compatible with the location and the lie of the land to be planted in Metropolitan France. To this must be added the high cost of moving such equipment and accessories, fuel and especially breakdown equipment, made more difficult on account of the weight. This is a greater drawback than fuel consumption which is limited in its effect; in fact, more often than not, high-powered equipment operates at a low working speed.
Heavy machines, therefore, are only worthwhile for large forestry enterprises or when the cost factor is of minor importance: for instance, when afforestation for soil rehabilitation and protection must necessarily be carried out even under difficult conditions, for the public welfare. Further, such machines should be in fairly general use so that they are readily available on the market and this does not appear to be the case in Metropolitan France.
Features of forestry equipment
It is usually better, therefore, to aim at the use of less powerful equipment. The requirements that equipment for planting work should meet are:
2. Extra reserve of power so as not to be constantly held up by small obstructions.
3. Means of avoiding visible obstructions (intermittent working, power lift, elevating device).
4. A system of overcoming obstructions, hidden or impossible to avoid. The machine must be reversible and retractable. In the absence of a mounted or semi-mounted tool, the (trailing) implement will be hitched to a rigid drawbar. In every case, a lift device that does not call for forward movement must be provided (winch on trailed implements, automatic lift device for semi-mounted or mounted implements).
5. The possibility of offering satisfactory working conditions to the operators from the standpoint of both safety and work effort.
6. Equipment that is easily kept in good repair (especially the engine). Even more so than in farming, a well organized repairs and spare parts service is of primary importance. The equipment is often used under trying conditions and consequently often breaks down. Because there is not much of the equipment in general use, replacements of parts are not easily obtainable.
The user of tree-planting equipment must always bear in mind that, unlike the farmer, he does not have to seek after a perfect and unbroken piece of work. If a few dozen yards are passed over no serious inconvenience will be caused. In the same way, since there are always liable to be hidden obstructions, it is often more economical to do the work in several stages. He should be content, at first, with a superficial working that will allow him to detect the operating difficulties. In trying to do a finished job all at once, the operator runs the risk of frequent hold-ups or breaking his machines.
These are the specialized machines, the engines and transmission gear of which are designed for the particular work to be carried out. Their disadvantage is that the amortization of the initial cost devolves on a single machine. Even in the case of multipurpose equipment it is usual to employ low-powered units, because with medium-and high-powered units, the price and weight of the motive power soon cease to be acceptable.
These can be used in two different ways:
(a) solely for traction for front. mounted or pushed implements;
(b) for both traction and driving force to operate the working parts of the equipment through a power take-off.
In the second case, there is a disadvantage that is not found in farming. The power take-off of a tractor takes up only part of the total power. Whenever an obstruction is met with, as is very often the case in forestry work, the tractor can always move forward but the total force available at the power takeoff is already absorbed, and so there is a risk of the equipment being damaged. In addition, transmission from the power take-off to the implement is usually effected through the cardan shafts which are rather fragile; they bear the brunt of the jolting of the machine in operation, and are not always strong enough to withstand the effect.
Tractors can be divided schematically into the following groups:
1. 20-30 horsepower, often too light for afforestation work;
2. 40-60 horsepower, medium. sized tractors sufficiently common to be easily obtainable, and which appear to be the desirable type;
3. 70-80 horsepower, heavy models that sometimes have to be used, but which have the disadvantage of being far less common than the above size.
4. 100 horsepower and over, very heavy tractors that are seldom available.
Crawler-type tractors. These have the advantage of better grip on heavy ground and a shorter turning radius, but the drawback of being less in general use and difficult to convey from one site to another. In addition, the tracks are weak parts. Their amortization is poor because of their high cost and rapid wear and tear. But crawler tractors are generally preferred for difficult operations on sloping land, when the use of broad tracks offers definite advantage.
Rubber-tyred tractors. These are more easily transported by road and are much more common. Their disadvantages when used on soft ground are more or less offset by the use of grip devices which are becoming popular (water-weighting, retractable flanges, chains and detachable half-tracks, rotapède tracks).
Lift device. This is an improvement that instead of being almost a luxury, as in farming, is often in planting work a necessity. It is essential for mounted implements that are generally much more easy to use than trailing implements. The hydraulic lift device is more rapid and more flexible than the winch, but the latter has the advantage of being sturdier.
A check list of useful equipment is given at the end of this article. It does not claim to be final but merely summarizes present practices.
Notes on particular items of equipment
Power cultivators. There is a wide range for various operations, particularly tillage.1 These machines have the great advantage of expediting soil preparation in nurseries, all the more to be appreciated as the period suitable for such work is usually short.
1 Not deep plowing, which is seldom required and is done with regular farm machinery.
Except in the case of very large nurseries, the tendency will be to look for power cultivators which, by their coupling system and range of adaptable implements, can be put to many uses, in order to allow of satisfactory amortization. If the power cultivator is to be trailer-hitched, it has to be equipped with rubber tyres.
Extremely light soils require only 5 horsepower, while average soils call for 8 to 9 horsepower and heavier soils for 10 to 12 horsepower.
Rotary hoes. Undoubtedly the most useful tool in a forest tree nursery, and far superior as regards quality of work to manual labor, is the horizontal-shaft rotary hoe, which pulverizes the soil surface to the extent necessary for the development
Of good root systems. There are two types:
(a) self propelled hoes designed for this work only;
(b) rotary hoes which can be fitted to power cultivators.
Clearing of surface vegetation
Cutter bar front-mounted power-driven mowers. These self-propelled machines are very useful for preparatory work or tending. The power required is about 5 horsepower, and it has been found that in many oases the width of the cutter bar should not exceed 1 meter for easy handling. Sometimes metal wheels are more suitable for working in the forest singe rubber tyres easily puncture.
Front-mounted cutter bare attachable to power cultivators. This combination achieved by some manufacturers has the advantage of providing a single machine for several uses, but the drawback, for large or medium size cultivators, of using more power than is needed for cutting. Forestry requirements make it difficult or impossible to use side-delivery cutter bars.
Trailed brush cutters. These consist of wheels or rollers equipped with knives which, if they are sufficiently heavy (the effect is obtained by their weight) and speedy, break up the vegetation in their path. The brush-cutter used in the Landes Region (Débrousailleur landais) is an example. They have the advantage of being sturdy and of lightly cultivating the soil, but can operate only where a tractor has been able to pass (Figure 1).
Vertical-shaft brush cutters. A horizontal blade is driven round a vertical shaft by the power take-off of a tractor. The drawback mentioned above (need for preliminary passage of tractor) also applies here (Figure 2).
Front-mounted scrub-clearing equipment, These include:
(a) power brush cutters (self-propelled machines which remove woody vegetation with a front-mounted disc);
(b) implements front-mounted on the frame of u tractor and operated by the latter's power take-off;
(c) portable equipment including a front-mounted implement and a small motor.
In the main, front-mounting allows operation among any type of vegetation provided that the equipment is sturdy enough, but this system necessitates protective devices for the operators and the removal of the cut vegetation. Further, its use on stony or rocky ground sometimes raises difficult problems.
FIGURE 1. MARDEN DUPLEX (DÉBROUSSAILLEUR): Marden Manufacturing Co. Auburndale, Florida, U.S.A.
FIGURE 2. "GYRO-84 BRUSH CUTTER: Servis Equipment Company, 1000 Singleton Boulevard, Dallas, Texas, U.S.A.
Surface soil cultivation
Tillage implements remove plant growth when not too dense.
These have the advantage of turning over the soil and bringing small obstructions (stones) to the surface (Figure 3). They ensure an efficient cleaning or scalping, that is, removal of the ground cover to eliminate competition. However, there is the risk of the point of the plowshare penetrating obstructions and becoming jammed. This drawback can be lessened by using rolling coulters suspended ahead of the share. In most cases, these machines cannot be used in forestry operations unless equipped with special devices for turning aside obstructions, or at least with a lift to raise the unit.
One-way plows. Farm plows can be used under easy and even fairly difficult conditions provided they are equipped with the attachments mentioned above. They have the advantage of throwing up ridges, sometimes useful on wet ground, and loosening the soil at less cost partly by deep and partly by surface tillage. They are not suitable for surface scalping work that cannot be carried out with a single moldboard. In fact, on the first plowing trip, since there is no bank to hold it, the one-way plow, when working at shallow depth, jumps the furrow at the slightest obstruction.
Listers or middlebreaker plows. These are like ridgers which turn the soil both to the right and to the left, and do not have the drawback mentioned above. Although in general use in farming, they are not sturdy enough for afforestation work, but special models can be obtained.
This type of equipment has the advantage over moldboard plows of overcoming obstructions, by either cutting or clearing them instead of jamming into them as does the plowshare (Figure 4). However, on shallow soil or where small obstacles are very frequent, such as stones which they cannot lift, disc implements are not satisfactory. They effectively cut up the surface herbaceous cover and turn over the top horizons, but they are usually less satisfactory for raising the soil.
Farm machinery. Disc machines are widely used in farming and many of them can be employed in forestry work. They include implements of the pulverizer type, in particular for tending work; medium weight machines (stubble plows and disc plows) for breaking up a dead and poorly decomposed soil covering, and possibly for subsequent operations; and heavy machines (heavy disc plows or trenching plows) which do a thorough plowing job when conditions are not too adverse. (In most cases it has been found that with disc implements it is best to reduce the number of discs to avoid tamping, or else to lessen the width cultivated).
FIGURE 3. HYDRAULIC UNIT DIGGING PLOW: William Begg and Sons, Tarbolton, Mauchline, Ayrshire, Scotland.
FIGURE 4. DISC Prow "JARDIN": R. Jardin, Volnay, Sarthe, France.
FIGURE 5. ROTAVATOR: Rotary Hoes of England, Station Road, East Horndon, Ulster, England.
FIGURE 6. ROOTER: Isaacson Iron Works, Seattle, Washington, U.S.A.
Forestry machinery. Generally heavy disc plows with a small number of discs (2 or 3), independent of each other to facilitate tillage when obstructions are frequent.
Horizontal-shaft rotary hoes (Figure 5)
Operated by power take-off. These implements, trailed or mounted, destroy the herbaceous vegetation, break up the dead soil covering and to a certain extent turn over the top layers. It has generally been found that it is better to concentrate the tractor power over relatively narrow rather than wide strips.
Self-propelled machines. These are lower powered machines which differ from the rotary hoe, mentioned for nurseries, only by the shape of the blades. Their handiness makes them very useful for loosening the top soil, namely, superficial hoeing. Those with independent tines pass over small obstructions more easily than the other models.
These implements have vertical teeth and are widely used in farming. There are two types:
(a) spike-toothed weeders and scarifiers;
(b) spring-toothed, like the harrow cultivator. These are constructed for work under adverse conditions (as in some vine-growing regions) and may be useful for surface loosening in afforestation work.
Vertical-shaft rotary equipment
The fitting of appropriate implements to planting hole diggers, which are dealt with below' will increase the range of their use by making them suitable for surface cultivation.
These serve for deep tillage and do not bring the subsoil to the surface, which is desirable in forestry work when the soil needs breaking up.
In forestry, much more than in farming, the aim is to facilitate root development. Apart from removing competing plants, deep tillage is often the most useful. Further, whenever there is a danger of water erosion, deep tillage, especially if carried out on the contour, will reduce runoff and increase rainfall penetration. It is to be noted that, whenever possible, it is desirable to do deep tillage before the winter, in order to take advantage of the frosts which help to mellow the soil.
These implements are widely used in farming and, mounted, can be employed advantageously on dissimilar, often fairly stony, ground, and easily loosen obstructions. Drainer attachments are useful in soils that require drainage.
These tools (Figure 6) are used in roadmaking and operate like the subsoiler, but have several tines and so ensure simultaneous loosening better than that obtained by successive trips with a single grubbing standard. They have the disadvantage of requiring a high tractive power.
Single or multiple-tined implements (grubbers, root-rakes) are fitted to the front of a tractor in place of the bulldozer blade (Figure 7). They do excellent deep tillage under very difficult conditions as they easily clear obstructions. They have the disadvantage of requiring a dozer-equipped crawler tractor and an operator capable of driving it.
Subsurface destruction of vegetation
There are various types of implements that cut the roots, below the surface, of the plant growth to be eliminated. They are not much used in France and wider trials would be worthwhile.
Soil loosening or planting-hole digging
Implements for intermittent work which, when continuous work is not possible owing to excessively difficult conditions, can be very useful in soil preparation. In lighter soils, the mechanical digging of holes should make for better quality planting and, consequently, lower cost with equal work.
Vertical-shaft rotary implements (Figure 8)
Self-propelled tools. Such are power hole diggers. According to the type used, they loosen the soil without removing or lifting it.
Mounted implements. These hole diggers mounted on a tractor or vehicle are operated by the motor of the latter. They do quicker work than those mentioned above but require higher power.
Portable power hole diggers. The gear is mounted on a frame, and the motor operates the rotary movement only. They solve the problem of transportation but call for considerable physical effort on the part of the operator, especially under difficult working conditions.
These are of the pick-hammer type and can be used for piecemeal subsoiling where ordinary tillage tools cannot operate.
Compressed air implements. These require compressors, and their use in forestry is almost impossible owing to the difficulty of moving them and the problems raised by the frequent handling of the air-intake pipes.
Self-contained units. These may present the same difficulty as the portable power hole diggers.
Terracing or contour trenching equipment
A crawler tractor fitted with a bulldozer and especially an angle-dozer blade, can be used for this type of work which is merely mentioned here as a reminder.
These are machines (Figure 9) generally drawn by tractors which, under exceptional conditions - loose ground free of obstructions, and large areas - reduce the cost of setting out planting stock. Small models of a market-gardening type can be useful in large nurseries.
This category comprises the implements constructed to solve a specific problem. They have the advantage of serving the purpose under better conditions and at lower cost, but their use has to be justified by the existence of large areas with similar conditions.
A. Nursery care
1. Power cultivators
2. Rotary hoes(a) Self-propelled rotary hoes
(b) Rotary hoes fitted to power cultivators
B. Clearing of surface vegetation
1. Herbaceous vegetation(a) Cutter bar front-mounted power-driven mowers
(b) Front-mounted cutter bars attachable to power cultivators
2. Woody vegetation(a) Trailed brush cutters
(b) Vertical-shaft brush cutters
(c) Front-mounted scrub-clearing equipment
C. Surface soil cultivation
1. Moldboard plows(a) One-way plows
(b) Listers or middle-breakers
2. Disc machinery(a) Farm machinery
(b) Forestry machinery
3. Horizontal-shaft rotary hoes(a) Operated by power takeoff
(b) Self-propelled machines
4. Tined implements
5. Vertical-shaft rotary equipment
D. Subsoil tillage tools
3. Modified dozers
4. Subsurface destruction of vegetation
E. Soil loosening or planting-hole digging
1. Vertical-shaft rotary implements(a) Self-propelled tools
(b) Mounted implements
(c) Portable power hole diggers
2. Percussion implements(a) Compressed air implements
(b) Self-contained units
F. Terracing or contour trenching equipment g. Planting machines
H. Special implements
(Article translated from an original French text).
FIGURE 7. CONTINENTAL TRACTOR 7200, equipped with three-tooth grubber.
FIGURE 8. MECHANICAL EARTH AUGER MODEL III: Les Fils d'Albert Collet. 41 rue Cardinet. Paris 17. France
FIGURE 9. TREE PLANTING MACHINE: Forestry Equipment Company, Jacksonville, Florida, U.S.A.
Interest in the development of forest utilization and woodworking industries is reflected in the continual demand for information on new equipment. The Forestry Division, FAO, collects such information and passes it, on request, to Member Governments: a selection is published here. FAO accepts no responsibility for the claims of manufacturers.
MARCONI DT45-C MOBILE UNIT.
- FM mobile station for operation in 152-174 MC band. Power output of transmitter 60 watts, sensitivity of receiver 0.4 microvolts for 12 db (decibel) to noise or 20 db quieting. Withstands extremes of temperature, humidity, vibration and shock.
Dynamic microphone and low-distortion receiver; less than 3 % distortion for 1.5 watts output. Universal design permits instantaneous changeover from 6 to 12 volt supply.
Canadian Marconi Company, 2442 Trenton Ave., Montreal 16, (Quebec), Canada.
DANARM FALCON WINCH.
- Can be carried over heavy ground to site and fitted in few minutes to Fury or Whipper Danarm chain saw engine in place of guide blade and chain, transforming it into tool for hauling, pulling or lifting. Heavy-duty ground anchor available. Weight (approx.): 20 lb. (9 kg.) less line; drum capacity: 125 ft. (38 m.) of 1/4 in. (6.4 mm.) cable; roller type bearings; lifting capacity: with Fury engine 15 cwt. 2 lb. (765 kg.), with Whipper engine 9 cwt. 2 lb. (458 kg.).
J. Clubley Armstrong Danarm Ltd., Abford House, Wilton Road, London S.W.1, England.
- Giant jungle destroyer designed to uproot heavy trees and underbrush. Large-size trees are pushed down with the blade raised about 10 ft. (3 m.) in the air; smaller, medium-size trees and underbrush are uprooted and carried away in one continuous operation with lowered blade. Each of six giant wheels has individual electric motor and gear reduction driven by generators, driven in turn by two powerful diesel engines. The pressure of machine upon ground is about that of a walking man, so it is well suited for work on swampy or sandy ground.
Top of crasher forms platform 39 ft. (11.8 m.) long and 11 ft. (3.3 m.) wide which can support more than 200,000 lb. (90,720 kg.).
R. G. Le Tourneau, Inc., 2399 South MacArthur. Longview, Texas, U.S.A.
ROOTER MODEL M.53-A.
- Extra heavy duty rooter engineered for use behind any 85-100 hp. crawler tractor. 5 shanks easily removed as well as plow steel shank teeth.
Full hydraulic control on 30 in. (75 cm.) penetration; heavy 2 x 9 in. (5 x 23 cm.) shanks; 36 in. (90 cm.) tyres.
Murray Manufacturing Company, 510 River Road, Modesto, California, U.S.A.
HOMELITE BRUSH CUTTER ATTACHMENT.
- In few minutes the chain saw can be converted into a brush cutter for clearing areas overgrown with brush, weeds and small saplings up to 3 in. (7.5 cm.) diameter.
To be mounted on a Homelite 17 model; power 3.5 hp; weight 22 lb. (10 kg.) approx.
Homelite Corporation, Port Chester, New York, U.S.A.
OLIVER JET TRENCHER.
- An addition to OC3 Tractor loader (approx. 22 hp). Adds extra versatility without limiting tractor maneuverability or loader operation. Attached or detached in 90 sec. Specifications: digs to 12 ft. (3.6 m.); loads to 7 ft. 4 1/2 in. (2.2 m.). Boom swing 180°. Attachment is hydraulically operated by 2 point hitch.
Buckets available in sizes from 12 in. (30 em.) to 36 in. (90 em.). 14 in. (36 em.) width is standard.
The Oliver Corporation, 400 West Madison Street, Chicago 6, Illinois, U.S.A.
SCHULSTAD MOBILE CIRCULAR POWER SAWS.
- Manufactured in four sizes:
Model 30: blade size 30 in. x 11 gauge (76 em. x 3.0 mm.); 5 hp single cylinder two-stroke engine. Weight 2 cwt 1 gr. (approx. 103 kg.); angle of cutting adjustable through 360° self-locking in any position; can be operated with blade rotating. Useful for fire wood cutting and general utility work.
Model 30 A: As model 30 plus reversible axle allowing absolute ground - level falling of timber. Equally effective when used with special rotary knives for fern or bracken cutting.
Model 36: Heavy duty self-propelled machine; blade size 35 in. x 10 gauge (89 cm. x 3.3 mm.); 10 hp air-cooled twin cylinder two-stroke engine. Power drive forward and reverse.
Model 48: Blade size 48 in. x 10 gauge (122 cm. X 3.3 mm.). Suitable for very large timber and for work in rough country.
W. Schulstad, Engineers, 26 Hardey Road, Marylands, Western Australia.
CAGO UNIVERSAL SWIVEL-SAW.
- General purpose saw with blades suited to both metal- and woodwork. Handle permits blade to approach work at any angle. Blade is tungsten steel for cutting metal, carbon steel for wood.
Cago (Sales) Ltd., Vernon House, 510 a, Coventry Road, Birmingham 10 England.
CARRIAGE WITH CLAMPING-DOG AND TELECONTROL Box.
- Eliminates all labor other than the sawer allowing 10 to 20-see. clamping. 2-direction motion of dogs; clamp first opens to fit shape of log and grip uniformly. Log is then aligned to blade, to allow sawing with grain of wood.
A loader allows loading of carriage and turning of logs during sawing operation by remote mechanical or hydraulic control.
Eta. Rennepont, 69, Quai de Valmy Paris X, France.
CHEVROLET TRUCK EQUIPPED WITH A POWR-PAK 4-WHEEL-DRIVE.
- Chevrolet 1/2-3/4-1-1 1/2 and 2 ton trucks can be equipped with Powr-Pak 4-wheel-drive, transferrable from one truck to another without damage to frame. Shifting in or out of 4-wheel-drive is done without stopping or clutching.
Truck equipped with this 4-wheel-drive climbs up to 70 % grades, while transporting logs, equipment, supplies and personnel; can also serve for snow plowing, hauling and road maintenance.
Napco Products Division of Napco Industries Inc., Minneapolis, Minnesota, U.S.A.
RUDDAN CANT HOOK.
- Enables one man to turn logs to any position while still away from machine, to bring them quickly to best position for clamping, also to turn logs already barked or partially squared.
Specifications: Electrically-driven; weight approx. 25 kg. (56 lb.). Consists mainly of switch or relay box to be attached to carriage of hoist and tackle, a control box with 2 push buttons, wires relaying switches to motor and contacts to buttons, and manipulation chains.
Ets. Ruddan, 31, rue de la Croix de Fer, Saint-Germain-en-Laye (Seine et Oise), France.
PYRAMID HYDRAULIC PLATFORM TRUCK MODEL 107.
- Designed for operating in conjunction with stillage. Fitted with foot-operated hydraulic pump to raise platform and lift stillage. Specifications: Loading platform: 59 1/2 in. x 26 in. (151 x 66 cm.); weight: 610 lb. (277 kg.); load 1,750 lb. (800 kg.); max. speed: 6 mph (10 km/h); platform elevation: 6 in. (15 cm.); 4-stroke air-cooled petrol engine 1 I/4 hp. 120 cc.
The Excelsior Motor Company Ltd., Kings Road, Tyseley, Birmingham 11, England.
FORK LIFT "SKID STAC".
- Load carrying plate and push-pull rack fitted with gripper blade, operated from truck hydraulic system. Rack supported by horizontal telescopic slides on each side. Push-pull and gripping blade mechanisms automatically sequenced by valve causing blade to grip before rack retracts and to release before rack extends.
In three models:
E3-20 for loads from 1,570 to 3,000 lb. (712 to 1,360 kg.);
E4-20 for loads from 2,380 to 4,000 lb. (1,079 to 1,814 kg.);
E45-20 for loads from 2,950 to 4,500 lb. (1,338 to 2,041 kg.).
Fork Trukcs Ltd., Warrington, England.
DOUBLE DRUM SANDING MACHINE, TYPE BD-B.
- Heavy cross-girted frame forming rigid mounting for sanding drums and pressure platens. Vertical adjustable conveyor unit with variable feed range. Special features allow either finish sanding with flexibly mounted conveyor, or thicknessing with rigid conveyor and flexible top front pressure. Specifications: Width admitted: 36 in. (91 cm.) and 42 in. (107 cm.); max. thickness admitted: 6 in. (15 cm.); feed speeds infinitely variable from 14 to 35 ft/min. (4.2 to 10.7 m/min.); width of abrasive paper on both sizes of machine: 24 I/4 in. (61.5 cm.).
T. White and Sons Ltd., Laighpark Works, Paisley, England.