Trofimoff valve

Last updated March 22, 2019

The Trofimoff valve (German : Trofimoff-Schieber) (also Trofimov, Troffimoff or Trofimof) is a springless pressure-compensation piston valve for steam locomotives.

German is a West Germanic language that is mainly spoken in Central Europe. It is the most widely spoken and official or co-official language in Germany, Austria, Switzerland, South Tyrol (Italy), the German-speaking Community of Belgium, and Liechtenstein. It is also one of the three official languages of Luxembourg and a co-official language in the Opole Voivodeship in Poland. The languages which are most similar to German are the other members of the West Germanic language branch: Afrikaans, Dutch, English, the Frisian languages, Low German/Low Saxon, Luxembourgish, and Yiddish. There are also strong similarities in vocabulary with Danish, Norwegian and Swedish, although those belong to the North Germanic group. German is the second most widely spoken Germanic language, after English.

Piston valve device used to control the motion of a fluid along a tube or pipe by means of the linear motion of a piston within a chamber or cylinder

A piston valve is a device used to control the motion of a fluid along a tube or pipe by means of the linear motion of a piston within a chamber or cylinder.

A steam locomotive is a type of railway locomotive that produces its pulling power through a steam engine. These locomotives are fueled by burning combustible material – usually coal, wood, or oil – to produce steam in a boiler. The steam moves reciprocating pistons which are mechanically connected to the locomotive's main wheels (drivers). Both fuel and water supplies are carried with the locomotive, either on the locomotive itself or in wagons (tenders) pulled behind.

Overview

The function of the valve is to improve efficiency when running light, with the regulator closed, such as when descending hills.^[1] The valve consists of the usual parts of a piston valve: two valve pistons with sealing rings, carried on a valve spindle driven by the valve gear. The difference with a Trofimoff valve is that the piston heads are free to slide on the spindle. When steam pressure is applied, under normal operating conditions, steam is admitted to the centre of the valve chest. This forces the valve heads apart against end stops on the spindle and into their normal working position. The valvegear works as usual.

The valve gear of a steam engine is the mechanism that operates the inlet and exhaust valves to admit steam into the cylinder and allow exhaust steam to escape, respectively, at the correct points in the cycle. It can also serve as a reversing gear. It is sometimes referred to as the "motion".

When the regulator is closed, there is no pressure to force the piston heads apart. The pistons remain stationary in the centre of their travel, uncovering the valve ports. There is now a clear path through the valves and the working pistons, allowing free running for the coasting locomotive.^[1]

Origins

The origins of this type of piston valve are not precisely known. It was probably developed in the 1920s in Germany, but its patents seem to have gone at that time to the Soviet State Railway. Other sources speak of it being developed by Bulgarian railway engineers. Russian sources claim that the valve was invented in 1908 by a Moscow Sorting Station service technician I.Trofimov (or Trofimoff, thus the name), but the Russian Revolution and Civil War slowed adoption, so the design gradually spread on the word-of-mouth, and was patented only in the 1920s.

The Russian Revolution was a pair of revolutions in Russia in 1917 which dismantled the Tsarist autocracy and led to the rise of the Soviet Union. The Russian Empire collapsed with the abdication of Emperor Nicholas II and the old regime was replaced by a provisional government during the first revolution of February 1917. Alongside it arose grassroots community assemblies which contended for authority. In the second revolution that October, the Provisional Government was toppled and all power was given to the Soviets.

Operation

Trofimoff valve of locomotive no. 41 1144 in open position. The piston valve heads are loose on the valve spindle, in the middle dead centre position. Left is a supporting element. When fitted, the valve bodies are exactly centred by the valve chest and the spindle through the housing (Tragbuchsen), so that the rod can move freely through the valve heads. Trofi2.jpg — Trofimoff valve of locomotive no. 41 1144 in **open** position. The piston valve heads are loose on the valve spindle, in the middle dead centre position. Left is a supporting element. When fitted, the valve bodies are exactly centred by the valve chest and the spindle through the housing (*Tragbuchsen*), so that the rod can move freely through the valve heads.

Cylinder block with valve chest (Schieberbuchse) on locomotive no. 41 1144. Left: the exhaust port Trofi3.jpg — Cylinder block with valve chest (*Schieberbuchse*) on locomotive no. 41 1144. Left: the exhaust port

The Trofimoff valve comprises the valve spindle, the piston valve heads slotted onto them and the two supporting plates (Stützplatten). When the engine is running under load the valve heads are forced by steam pressure onto the support plates and work like standard pistons (Regelkolbenschieber). If steam admission ceases or, on a steam locomotive, the regulator is closed, the pressure drops, the valve heads remain in the inside dead centre position near the centre of the cylinder due to the tension of the piston rings. The valve spindle continues to move backwards and forwards with the support plates attached to it, without disturbing the valve heads. In this way, perfect pressure balance is achieved, thus ensuring excellent light-running conditions for the steam engine or locomotive.

The support plates fixed to the valve spindle also have a piston ring. This slows down the closing of the movable valve heads. Narrow gauge locomotives (such as the DR Class 99.23–24) do not have these piston rings. As a result, when the locomotive switches from running light to running under load there is a characteristic clicking noise as the pistons close. This piston ring on the support body was a further refinement by the former Meiningen repair shop.

The Meiningen Steam Locomotive Works is a railway repair shop in Meiningen, Germany. It is owned by Deutsche Bahn and has specialised in the maintenance of museum steam locomotives since 1990, having extensive experience in maintaining steam engines. Today, customers of the factory include railway museums and museum railways from all over Europe. The factory is responsible for the safety inspections of all operational German steam locomotives.

So that the entire locomotive cylinder block does not have to be changed when the valves are damaged, they are housed in special chests. The valve chest consists of two elements which are forced into the cylinder block from the front and rear. Using special boring tools this chest can be bored out several times during maintenance. In the last illustration the junction of the two halves of the chest and the right-angled ports can be seen towards the rear. These are steam admission ports. Steam is admitted to the pistons of the steam engine through the front diagonal slits. The front area, outside the valve chest, is called the exhaust chest and discharges, via the exhaust pipe, the riser (Standrohr) and the blast pipe cap (Blasrohrkopf) centrally, underneath the chimney of the locomotive.

The motion of the valve heads alternately opens and closes the diagonal slits or steam ports, thus controlling the admission and exhausting of steam in the steam engine.

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The cylinder is the power-producing element of the steam engine powering a steam locomotive. The cylinder is made pressure-tight with end covers and a piston; a valve distributes the steam to the ends of the cylinder. Cylinders were cast in cast iron and later in steel. The cylinder casting includes other features such as valve ports and mounting feet. The last big American locomotives incorporated the cylinders as part of huge one-piece steel castings that were the main frame of the locomotive. Renewable wearing surfaces were needed inside the cylinders and provided by cast-iron bushings.

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References

1 2 Bell, A. Morton (1948). Locomotives: Their Construction, Maintenance and Operation. One (Sixth ed.). Virtue & Company. pp. 70–71.

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[Bell-1] 1 2 Bell, A. Morton (1948). Locomotives: Their Construction, Maintenance and Operation. One (Sixth ed.). Virtue & Company. pp. 70–71.