How to use Tractive in a sentence
Thus the diagram shows the tractive force at any instant.
Moreover, the average tractive power per locomotive and the average capacity per freight car advanced greatly in this period, although specific figures cannot be given.
There are certain fundamental relations common to all tractive problems, and these are briefly considered in §§ i and 2, after which the article refers particularly to steam locomotives, although §§ 4, 5, 7, 8, 9, and 10 have a general application to all modes of traction.
The fundamental condition governing the design of all tractive machinery is that the wheels belonging to the axles to which torque is applied shall roll along the rails without slipping, and exert a tractive force on the train.
The fundamental relation between the applied torque and the tractive force F will be understood from fig.Advertisement
In the first case all the driving is done on one or at most two axles, sufficient tractive force being obtained by coupling these axles when necessary to others carrying heavy loads.
Thus if the maximum horse-power which a locomotive can develop is woo, the tractive resistance R, at 60 m.
A side wind causes excessive flange friction on the leeward side of the train, and increases the tractive resistances therefore very considerably, even though its velocity be relatively moderate.
To obtain the tractive force the weight on the coupled wheels must be about five times this amount - that is..
Dividing thr Hugh by V and multiplying through by 550, 2240W 2240Wa R =Were+W vry t G (23) ' 'an expression giving the value of R the total tractive resistance.Advertisement
First, it must be able to exert a tractive force sufficient to start the train under the worst conditions possible on the railway over which it is to operate - for instance, when the train is stopped by signal on a rising gradient where the track is curved and fitted with a guard-rail.
If p is the mean pressure at any speed the total tractive force which the engine is exerting is given by equation (25) above.
Then the tractive force is, from (25), (149 X 19 2 X2.166)/6.25 =18,600lb =8.3 tons.
The engine can only exert this large tractive force so long as the mean pressure is maintained at 149 lb per square inch.
Thus although at a slow speed the engine can exert a tractive force of 18,600 lb, at 60 m.Advertisement
It will be seen at once that with a tractive force of 7400 lb a weight of 37,000 lb (=16.5 tons) would be enough to secure sufficient adhesion, and this could be easily carried on one axle.
When the road leads the train up an incline, however, the tractive force must be increased, so that the need for coupled wheels soon arises if the road is at all a heavy one.
It is used to a limited extent for mountain-grade goods traffic, and has the advantage over the " Consolidation " or eight-coupled type of lighter axle loads for a given tractive capacity.
Tractive Force of a Magnet.-Closely connected with the results just discussed is the question what is the greatest tractive force that can be exerted by a magnet.
If H could be increased without limit, so also could the tractive force.Advertisement
Webb to measure the tractive resistance of trains on the London & North-Western railway, a tractive pull or push compresses two spiral springs by a definite amount, which is recorded to scale by a pencil on a sheet of paper, drawn continuously from a storage drum at the rate of 3 in.
Coupling Rod These couple driving wheels of the same size together to spread the tractive effort over the coupled wheelbase.
The torque corresponding to this couple is F 1 X z D = 2µWID, and hence follows the fundamental relation, 2T = 2F 1 D = 2µWID, or if W now represents the weight supported by the axle, F will be the tractive force exerted on the frame by the two axle-boxes to propel the vehicle, and the more convenient relation is established, T=2FD=2µWD (3) If T has a greater value than this relation justifies the wheels will slip. F is called the " tractive force " at the rail.
The magnitude of F when p and e are put each equal to unity, is usually called the tractive force of the locomotive per pound of mean effective pressure in the cylinders.
There are two steel-clad series-wound motors of 36 B.H.P. For a test load of 120 tons the tractive force is 70 lb per ton, which is sufficient for acceleration, and maintaining speed against wind pressure.Advertisement