SOME GERMAN fuzeS

This old little German percussion fuze was organized on a principle somehow comparable to the French Budin Mle 1875 fuze. The safety of the Gr Z c/82 was doubled :

• the top head was descending into the fuze head by inertia at the shot departure, therefore bringing the starter in a position that could be hit by the percussion pin,
• at rest, the top of the percussion pin was hidden inside of a mobile inertia block, that was also armed at the shot departure

It must be noted that no safety spring was preventing the percussion pin from hitting the starter once armed, during the flight.

An early similar fuze, the Gr Z c/80, only included one safety device with the mobile inertia block hiding the percussion pin.

This fuze was designed for high explosive ('Gr' = Granate - Obus explosif) and incendiary high calibre shells. It had to be mounted in association with a detonator and a relay-charge. It was mainly used with the projectiles of the

• 150mm heavy field howitzers (sFH, sFH02, sFH13)
• 150mm heavy coast howitzers (sFH Kst)
• 150mm Ringkanonen (15cm RK et 15cm lRK)
• 210mm mortars under turret

A variant named Gr Z c/82 (Kp) was equipped with a safety spring and a different inertia block. Externally, it was only distinguishable by the presence of a steel cap covering the fuze head.

That fuze was entirely made of brass. Purely percussion-type and without delay, this old Gr Z 92 fuze was equipped with a safety pin, to be removed before the shot. That action allowed the movements of a first percussion system, whose sliding starter-bearer went in contact with the fixed percussion pin, igniting a big gun powder grain.

The burning of this gunpowder grain allowed the movements of a second inertia percussion system, situated in the fuze tail, so that at the shock time, the starter-bearer was violently projected against a fixed percussion pin, provoking the relay-charge explosion.

This fuze was dedicated to the explosive ('Gr' = Granate - Obus explosif) or gaz heavy shells. It was mainly used with the ammunitions of the

• 150mm heavy field howitzers (sFH02, sFH13)
• Long 210mm mortars
• 210mm mortars model 1902 and 1910

Brass fuze derivated from an initial Gr Z 96, with a steel mantle. The Gr Z 96/04 fuze is a classical conception for a percussion fuze with optionnal delay, equipped with two selectable different inertia percussion systems (one with delay, the other one without), with a pin for security handling.

A 100 grammes picric acid detonator was integrated at the bottom part of the fuze.

The optionnal delay was selected by a lever rotation, placed on the 'oV' position (Ohne Verzögerung - without delay - let both percussion systems active) or on the 'mV' position (mit Verzögerung - with delay - desactivate the non-delayed percussion system)

Another characteristic of this fuze was its additional safety system for the detonator, inherited from the older type fuze Gr Z 96. At rest, the detonator was placed within an isolated detonation room in wich it could explode without communicating the energy to the surronding relay-charge. But at firing time, the combustion of a compressed black powder grain was freeing its movements inside a brass tube so that the landing shock inertia could push it just in front of windows communicating with the explosive load.

That fuze was dedicated to the explosive shells ('Gr' = Granate - Explosive shell) of heavy caliber. It mainly equipped the HE projectiles of the

• 150 mm heavy field howitzers (15cm sFH, sFH02, sFH13)
• 150mm long tube guns
• 150mm bind tube guns
• 210mm howitzers

Those types of heavy shell needed quite a big detonator to explode (100 gr. picric acid)(

Brass or zinc alloy fuze, with steel cover.

The Gr Z 04 fuze function with optionnal delay implied the presence of two different percussion systems, one having an integrated delay, and the other with no delay, just like in the Gr Z 96/04 fuze (seen before). Those systems were selected via a slight rotation of the upper rotating disc ('O/V').

Equipped with a 90 gr. acid picric detonator, it was used with the HE projectiles of

• 100, 130, 150, 150 (long) mm guns
• 150 mm heavy field howitzers sFH02, sFH13
• 6in & 8in Russian, and 150mm Belgian captured howitzers
• 210 mm mortars
• 210 mm Belgian captured howitzers

The mobile pieces of the percussion systems were blocked at rest condition with a security pin.

A new mark, named Gr Z 04/14, has been produced since 1914, using the head of the Gr Z 04, but the detonator of the Gr Z 14 (see below), that is without detonator security stem.

The Gr Z 14 is a brass fuze with a steel cover, and 45 mm diameter thread. Evolution and simplification of the Gr Z 04, the inertial percussion system was armed by a a concutor with security pin.

The modified version (Gr Z 14 'n/A' - neue Art) added another security pin on the main percussion system, removed by the centrifugal force.

That fuze was equipped with a 63 gr. acid picric detonator.
It was mostly used with the shells of the

• 90, 100, 120, 150 mm guns
• 150 mm heavy field howitzers sFH02, sFH13
• 150mm Belgian captured guns
• 6in Russian captured howitzers

You will easily find that fuze in large quantities on the former battlefields. Unhopefully, most of these objects are very corroded now, because most of them were made in aluminium. Some versions had a zinc alloy or brass body, and resisted increasingly better. So did the steel caps of the aluminium ones.

Basic fuze of the explosive or gaz shell of the 77mm FK 96 n/A field gun, equipped with a 20 grammes acid picric detonator, the KZ 14 had a simple and economic design. Classic functionning of a German percussion system with black powder grain and stem arming.

It was usually used with the explosive and gaz shells of the

• 77 mm FK 96 n/A et FK 16 field guns

4 marks have been developped on the original KZ 14 basis :

• KZ 14 Fb with additional centrifugal security
• KZ 14 Vorst with safety pin
• KZ 14 mV with delay
• KZ 14 n/A with minor intern modifications

These versions are hardly distinguishable on items found on the battlefilds, when there no markings visible

That massive fuze weight impressed me when I encountered my first item, giving to this head alone an evident lethal power when flying. The HZ 14 is a classical German percussion fuze, with an internal organisation similar to the one of the KZ 14 (see above) with arming by combustion of a compacted powder grain ignited by a concutor, blocking a stem in contact with the inertia block. It has been initially designed for light howitzers. It could be made of different metals, including steel, brass and zinc alloy.

Three versions followed the first one (HZ 14, introduced in 1914) that was subject to premature explosions inside the tube bore :

• HZ 14 Fliehb. (Fb.) with centrifugal security
• HZ 14 Vorst with safety pin
• HZ 14 Vorst Fliehb. with safety pin and centrifugal security

Equipped with a 55 gr. acid picric detonator, it was used with the explosive or gaz shells of the

• 90 mm K73/88 guns
• 100 mm K97, K04, K14 guns
• 100 mm protected guns KiSL et TK
• 120 mm sK 12cm heavy guns
• 105 mm lFH 98/09 light howitzers
• 105 mm lFH 16 light howitzers
• 105mm lFH Kp Krupp light howitzers
• etc...

A new family of percussion fuzes was introduced from 1916 by the German Army. The 'ancestor' of this series was the KZ 16 m.V. that has been rapidly replaced by the LKZ 16 of identical inside mechanism, but elongated head.

The LKZ16 fuze is quite commonly found on the former battlefields. Its main characteristic is being of a very simple conical look, since the usually observed part of the shell is just a steel cone. In fact, this part is only a steel top that covers the aluminium and brass percussion mechanism. The shape has good aerodynamics properties and was particularly designed for elongated shape shells with improved range.

The fuze mechanism is composed by a double security system based on the centrifugal force :

• two security pieces, blocked by springs but allowed to move thanks to the shell spin are stopping the starter-bearer movements at rest condition,
• a lock that can slide horizontally under the effects of the same force is separating the percussion mechanism from the relay-charge.

, The delayed models have a little picric acid relay charge in this sliding lock ('LKZ 16 m.V.'). This relay charge is not present in the non-delayed models ('LKZ 16 o.V.').

Equipped with a 23 gr. picric acid charge, it was in use with the explosive projectiles of the

• 77 mm FK 96 n/A et FK 16 field guns
• 3 inches infantry guns (mountain russian guns model 1909)

Very similar at the first sight to the LKZ series because of the conical shape and dimensions, this fuze is indeed quite different. The EKZ 16 is an intantaneous model ('Empfindlicher Kanone Zunder', whose explosion was occuring before the shell could dig into the ground, at the very first contact with the objective.

In order to function that way, a steel or aluminium alloy percussion stem was axially inserted in the steel or zinc alloy fuze head. When the stem hitted the goal, it was pushed towards the concutor, making this piece hit the starter-bearer located at the base.

The fuze mechanism is composed by a double security system based on the centrifugal force :

• two security pieces, blocked by springs but allowed to move thanks to the shell spin are stopping the starter-bearer movements at rest condition,
• a lock that can slide horizontally under the effects of the same force is separating the percussion mechanism from the relay-charge.

, The fuze was delivered to the batteries with the percussion rod separated, and a lead cap hiding the top hole, for an assembly before the fire.

Equipped with a 23 gr. picric acid charge, it was in use with the explosive projectiles of the

• 77 mm FK 96 n/A et FK 16 field guns

The EKZ 16 fuze is typically used for the 77 mm gaz shells (blue cross).

The EKZ 16 c fuze was an elongated version of the instantaneous percussion fuze EKZ 16, with equivalent intern organization. The only noticeable difference relies on the first centifugal security mechanism that acts on the percussion rod instead of acting on the starter bearer.

Equipped with a 23 gr. picric acid charge, it was in use with the explosive projectiles of the

• 77 mm FK 96 n/A et FK 16 field guns

The KZ 16 f10cmK was a percussion fuze, equipped with a long percussion rod, similar to the one of the EKZ16. Just like in this latter, the percussion rod was blocked at rest by two centrifugal locks maintained by springs, that were removed under the action of the shell spin during its flight.

A double centrifugal security, identical to the one described in the HZ16 fuze, equipped the inertia block and the detonator (excentric sliding drawer).

That fuze was in use with the high explosive shells of the

• 10cm Mle 1897, 1904, 1907, 1914, 1917 guns (10cm.K.97, 04, 07, 14, 17)
• 10cm guns under shelled mounting (10cm.K.I.S.L.)
• 10cm guns under turret (10cm.T.K. et T.K. verst.)
• 10cm short guns under turret (Kz.10cm.T.K.)

The fuze KZ16f10cmK, made of steel, alumium or zinc alloy, seemed to be used as a substitution of the HZ14 vorst, for the above mentionned guns.

Detonator charge : 70 grammes of picric acid.

The HZ 16 percussion fuze, with optionnal delay, is typical of the middle-war years, by its materials choice : the head and the detonator are in steel, the body and the mechanism are in zinc-alloy.

The classical percussion mechannism (inertia block and percussion pin) was blocked at rest by a centrifugal security system composed of two diametrically opposed pins equipped with springs. It was communicating to the rear of the fuze by two parallel channels.

One of the channels was equipped with a black powder grain delay. A external selector allowed, by screwing a rod, to close the non-dealyed channel when one wanted to use the delayed function ('m.V. position).

An additionnal security, comparable to the one of the LKZ 16 fuze was added at the rear of the fuze. It was composed by a drawer, sliding in a notch under the action of the centrifugal force : blocked at rest by two centrifugal pins equipped with springs, it sealed the communicating channel between the detonator and the fuze head. Under the action of the shell spin, during its flight, it slided and put an exploding channel in the pyrotechnic axis.

That fuze equipped the gas and explosive shells of the

• 105 mm light field howitzers lFH 98/09
• 105 mm light field howitzers lFH 16
• 105 mm light field howitzers lFH Krupp ('Kp')

The EHZ 16 fuze is a variation of the HZ 16 fuze that has been presented above.

It consists in the addition of an axial metallic rod that pushes directly on the percussion pin. Thus, at target contact, the percussion pin is thrown onto the starter-bearer, giving an instantaneous function of the fuze, igniting the main charge just before the shell enters in the earth.

The rod was only put into place before the shooting, and only if an instantaneous function was required. When the rod was not inserted, the EHZ 16 fusze behaved just as the HZ16.

That fuze equipped the gas and explosive shells of the

• 105 mm light field howitzers lFH 98/09
• 105 mm light field howitzers lFH 16
• 105 mm light field howitzers lFH Krupp ('Kp')

Detonator charge : 58 grams picric acid

The EKZ 17 fuze is externally almost identical to the EKZ 16 fuze, even if the inner organization is entirely different. It is again an intantaneous model, whose explosion was occuring before the shell could dig into the ground, at the very first contact with the objective.

In order to function that way, a steel or aluminium alloy percussion stem was axially inserted in the iron or zinc alloy fuze. When the stem hitted the goal, it was pushed towards the concutor, making this piece hit the starter-bearer located at the base.

The mechanism was far more simple than the EKZ 16 one particularly with its unique safety system, based on a radial spring stopping the stem movements, but compressed by the centrifugal force during the shell flight.

With a 23 gr. picric acid detonator, this fuze equipped the high explosive and gaz shells of the

• 77 mm FK 96 n/A et FK 16 field guns

The EKZ17 fuze is typically used for the mighty 77 mm gaz shells, with green, yellow or blue crosses, indicating a different chemical composition.

The EHZ 17 fuze is very similar to the instantaneous fuze EKZ 17 presenteed above, but for the rounder head shape and the 57.5mm thread diameter.

With a detonator of 23 gr. of picric acid, it equipped the gas and explosive shelles of the

• 105 mm light field howitzers lFH 98/09
• 105 mm light field howitzers lFH 16
• 105 mm light field howitzers lFH Krupp ('Kp')

Faced to the irruption of British tanks on the Somme battlefield as soon as summer 1916, the Germans had to quickly invent the corresponding anti-tank weapons. Re-inforced explosive charge grenades, landmines and dedicated high power rifles were distributed to the infantrymen until the end of the war, but early fights experience showed that conventional high explosive shells of the commen 77mm fieldguns could 'do the job' pretty well if hitting the target at sensitive places under good ballistics conditions (speed, angle).

The German Army required the developement of a specific armor-piercing 77mm shell on the basis of the conventional high explosive 7,7cm K Gr 15, named 7,7cm K Gr 15 mP ('mP' ='mit Panzerkopf'). This high explosive shell, theoritically efficient up to a 5000 m range but practically used within distances lower than 1500 m, was also containing a smoke generating composition in its bottom. It was topped by a massive extra-hard quenched steel cone able to pierce 20mm armor plates, and contained a specific delayed percussion fuze that triggered the explosion once inside the vehicle.

The Aufschlagzünder mV fur K.Gr. 15 m.P. fuze had an aluminium body. Its intern mechanism was a percussion-type one, with a centrifugal safety device, and a small delay both mechanical (the starter flame had to follw a sinuous path) and pyrotechnic (with a compressed black powder disc). The fuze and cone thread diameter was 51.5mm.

Equipped with a 25g TNT detonator, this fuze was used with the armor-piercing explosive shells of the

• 7,7cm FK 96 n/A fieldguns
• 7,7cm FK 16 fieldguns

This projectile was most probably the one used in Flequières on November 20th 1917 by the German Leutnant Müller, sole survivor of its 7,7cm FK96 n/A battery, who destroyed 16 British tanks before being killed, in one of the many famous heroïc acts of WW1.

Double effect fuze, the Dopp Z 91 included a classical percussion system in the tail, and a single rotating disc time system. The graduation figures from 3 to 44 seconds, and with a cross for a pure percussion function, were engraved on the upper mobile upper cone.

Fully made of brass, it had a security pin (two rods) blocking the time system concutor. The arming system of the percussion device was quite special, based on the movements of a tube sheltering the starter-bearer, blocked by a powder grain ignited by the concutor at the shooting time, and therefore without any stem, unlike most of the German fuzes.

That fuze mostly equipped the projectiles of the :

• 90 mm guns (explosive and shrapnel shells)

Double effect fuze, the Dopp Z 92 was an evolution of the Dopp Z 91, based on the same principles, therefore having a classic percussion system in the tail and a rotating discs time system in the upper cone.

The lower disc, mobile, was engraved with graduations from 1 to 29 seconds, and a roman cross for the pure impact percussion function.

Entirely made of brass, it had a security pin blocking the concutor of the time system. The same specific arming system of the percussion device (with a powder grain in spite of the classical German stem system).

Different marks have been produced :

1. Dopp Z c/92 : graduated from 1 to 28 seconds
2. Dopp Z c/92 F H : graduated from 3 to 36 hectometers
3. Dopp Z c/92 K15 & 10cmK : graduated from 1 to 26 seconds
4. Dopp Z c/92 Brlg. : graduated from 2 to 41 seconds

That fuze mostly equipped the projectiles of the :

• 90, 120, 130 and 150 mm (shrapnel) guns
• 150, 160 and 210 mm (shrapnel and explosive) howitzers

The inner mechanism of this Dopp Z92 nF fuze is strictly identical to the famous Dopp Z92 fuze (here above), as this appears evidently on the scheme. The only differnec between the two fuzes is the shape, more round, and the material (either all brass or aluminium plus brass).

The lower disc (that disappered on the showed item) was graduated from 2 to 41 seconds, and with a special mark for the pure percussion functionning.

This fuze was mostly equipping the projectiles of the :

• 90, 100 et 150 mm guns (shrapnel shells)
• 150 mm sFH 13 and sFH 02 howitzers (incendiary and explosive shells)

That Dopp Z 96 n/A revolving discs time fuze was also equipped with a percussion system, giving a sense to the name 'double effect' : 'Dopp' = Doppler (double). It was very common, since at the beginning of the war it was only used with the shells of the

• 77mm FK96 n/A and FK 16 field gun.

It is therefore often found on the former battlefields, or in the museums.

Used without modification on the shrapnel shells, or added with a detonator in the case of the explosive shells, its static disc was graduated from 0 to 50, for an ignition after a flight from 0 to 5000 meters (the n/A marks were successively graduated up to 5350, 7150, 6500 and 7000 metres), and the mobile disc was engraved with the index.

The concutor (for the ignition of the time system) was located in the axis of the head, and the classical percussion system (for an occasionnal function at the impact time) in the tail. The most ancient models were equipped, at rest, with a safty pin. The newer ones (n/A) saw the disappear of this safty pin.

The Dopp Z 15 fuze was developped in 1915, and was a two-discs type. The lower disc was the rotating one, and was graduated from 0 to 41 seconds. At the departure, this rotating disc was fixed by a double inertia pin.

Two percussion systems, one with delay, the other without delay, that could be selected by an external lever, allowed to choose the depth of the explosion. A security pin was inserted into two holes in stock condition.

That fuze mainly equipped the explosive, test and smoke shells of the :

• 100mm K, K 04 and K 14 guns.
• 130mm K guns
• 150mm long guns
• 150mm Heavy field howitzers sFH 13, 18 and 04

90 g picric acid charge

The HZ05 fuze was designed for the German famous universal shell of the light howitzers lFH 98/04. But the lack of success of those hybrid munitions (both high-explosive and shrapnell) induced the specialisation of a new series of derivated fuzes, allowing a high level of simplication of the mechanism.

The HZ05 Gr. (for 'Granate' - high-explosive shell) is the simplification destinated to the high explosive shells only, then having no cental canal nor radial windows for the communication of a flame to the charge, but included a detonator and a relay-charge.

The choice of the with or without delay functionning was made by a rotation of the upper disc marked 'mV', selectionning one of the two existing percussion systems. The time system, that could be set by the rotation of the lower disc, was graduated from 3 to 53 hundreds of meters and a cross for the percussion function.

The time system mechanism was ignited by a classical concutor system situated in the tail, blocked in rest condition by a safety pin. The classical German percussion mechanism, also locatoed in the tail, was armed by a usual 'black powder grain + stem'.

Hybrid (body, head and upper rings in brass, lower rings in aluminium, and some parts in steel), most of those fuzes that can be seen nowadays have lost their aluminium parts due to corrosion.

That fuze usually equipped the high explosive or gas projectiles of the

• 105 mm light field howitzers lFH 98/09
• 105 mm light field howitzers lFH 16
• 105 mm light field howitzers lFH Kupp ('Kp')

The HZ05 existed through different marks, most of them being fuze-detonators. The HZ05 Schr. (for 'Schrapnell') showned here does not have an attached detonator, and was therefore only dedicated to the shrapnel shells.

Composite (steel or zinc alloy cap, aluminium discs, steel and zinc alloy body), it was engraved with graduations from 3 to 70 hundred of meters and a roman cross for impact percussion function on its lower mobile rotating disc. The time system was ignited by a classical concutor, fixed at rest condition by a safety pin.

The classical percussion system, located in the tail, was armed by a slightly new 'gunpowder grain + blocking stem' German system.

That fuze was usually used on the shrapnel projectiles of the

• 105 mm light field howitzers lFH 98/09
• 105 mm light field howitzers lFH 16
• 105 mm light field howitzers lFH Kupp ('Kp')

In its initial mark KZ 11, this fuze has been designed to equip the famous German 'universal shells', that was studied in the 'projectiles' webpage of this site.

This particuliar shell (with lead balls and back gunpowder room for the shrapnel function, thickened steel walls and TNT bedding of the balls for the explosive function) implied the use of specific fuzes.

In addition to the classical percussion system and revolving disc time system (the upper rotating disc was engraved with graduations fron 2 to 50 hundred meters) and powder grain concutor, classical for a German 'double effect' fuze, the HZ 11 model was equipped with a lever the direction of the lower disc flame, either to the 23 gramms picric acid detonator (explosive function, position 'G' - 'Granate'), either to 8 lateral windows communicating with the back gunpowder room (shrapnel function, position 'S' - 'Shrapnel').

That fuze was mainly used with the projectiles of the

• 77 mm FK 96 n/A and FK 16 (universal shells)

That additionnal sophistication had a cost : this was one of the most complex fuzes of the period, with more than 105 different brass parts !

Other versions appeared during the war, for use with 'usual' explosive or gas shell in conventional or anti-aircrafts role :

• KZ 11 Gr with a higher steel cap, for 7.7cm FK96 n/A or FK16 high explosive or gas shells
• KZ 11 Gr lB idem with extended range from 2 to 72 hectometers ('lange Brennlänge')
• KZ 11 Gr nur Bz without percussion system ('nur Brennzünder') for anti-aircraft role
• KZ 11 Gr lB o Az graduated from 3 to 30 seconds for use with the russian 7cm62 in AA role

Externally, the LKZ 11 Gr fuze looks like a simple aerodynamic improvement of the KZ 11 Gr fuze seen above, with an elongated hat. However, this fuze differs by the lack of selector switch (the flame is going directly to the detonator, like it is supposed to be for a high explosive ('Gr') fuze), and by a different percussion system.

The early versions were graduated from 4 to 72 hectometres. A later version saw the graduations limited to 5O hectometres, and in that case the fuze was marked 'k.B.' (Kurze Brennlänge - shortened fusing length).

Equipped with a 23 gr picric acid detonator, it was mainly used with the explosive shells of the

• 7.7cm FK 96 n/A and FK 16 guns

The name of that fuze, 'l.W.M. Zdr.' - 'Leichte Wurf-Minen Zünder', specified its exclusive use with the bombs of the 77 mm light minenwerfers :

• 77 mm light trench mortars 'lWM', explosive or light gaz shells
• 77 mm light trench mortars mod 1916 lWM n/A, light gaz shells

Entirely built in brass, it was made of a classical revolving discs time system (with the lower mobile disc graduated from 7 to 24 seconds, and a central concutor blocked by a safety pin), and a classical gunpowder grain + stem arming system.

The lWMZdr2 fuze was a slight modification of the previous IWMZdr, therefore also dedicated to light trenchmortars.

The only modifications were :

• a relay-charge screwed on the detonator
• a double rods safety pin

These modification were only internal and are not visible outside, but for the fuze marking that shows lWM Zdr 2

There was a variant of that fuze, introduced in 1918, with a threaded hollow tube inserted at the top of the fuze, supposedly for handling purposes

Note that one of the models shown in the pictures shows a intermediate disc that is a modification made by the trench art soldier who transformed that ordnance into an inker...

This fuze name, 'Z.s.u.m.W.M.' - 'Zünder für schwerer und mitteler Wurf-Minen', specifies its exclusive use with the bombs of the middle and heavy minenwerfers.

The items stamped 'Z.m.W.M.' were strictly dedicated to middle trench mortars :

• 170 mm middle trench mortars mWM 13 or o/A, explosive, incendiary or gaz shells
• 170 mm middle trench mortars mWM 16 or n/A, explosive, incendiary or gaz shells
• Smooth 180 mm bomb-laucher (Projector), gaz or blue-crossed shells
• 250 mm heavy trench mortars sWM, explosive long shells, explosive or gaz half-bombs
• 250 mm heavy trench mortars sWM 16 or n/A, long explosive bombs.

made of brass, like the small IWMZ item of the 77 mm minenwerfer, this fuze is also composed of a classical time-delayed disc mechanism, where the mobile inferior disc is graduated from 7 to 21 seconds, with central concutor blocked by a safety pin. Some models have a centrifugal force security.

A symetrical percussion system with two opposite starters and percussion pins (to the front and to the rear) made sure the explosion occured whenever the shell felt on his back or on the nose (but theoritically not on the side !).

That fuze could be covered with an aluminium or thin steel cap for hiding the flames during night time use.

This fuze name, 'Z.s.W.M' - 'Zünder für Schwerer Wurf-Minen', specifies its exclusive use with the projectiles of the higher calibre minenwerfers of the beginning of the WW1 :

• Heavy trench mortars sWM, cal. 250 mm, elongated explosive bombs or gaz half-bombs

Made with brass and aluminium head, it had, like the fuze above, a symetrical percussion system with two opposite starters and percussion pins (to the front and to the rear) making sure that the explosion occured whenever the shell felt on his back or on the nose. The time-delay mechanism was a classical disc mechanism, where the mobile superior disc was graduated from 1 to 15 seconds.

A safety pin and a hat were protecting the percussion system during the handling and transport

This fuze has been replaced by the here above ZsumWM fuze

This time again, the German spelling of this fuze is quite clear : 'Boden Zunder' means 'bottom fuze'.

The Bd Z 06 was then a fuze that was screwed on the bottom of heavy explosive shells, whose nose cone was massive to improve the penetrating properties of the projectile.

This fuze was mainly used with the projectiles of the :

• 130 mm guns (explosive shells)
• 150 mm guns on coast mounting Mle 97 (explosive shells)
• 210 mm mortars 'Morser' (explosive shells)
• 280 mm coast howitzers (explosive shells)

Entirely made of brass, this fuze has two percussion systems aligned in the same central axial canal, blocked by a bolt hold by a grain powder ignited by the departure gazes.

In the case of a non-delayed function, programmed by a positionning of the bottom lever on the 'o/V' mark, both the percussion systems are freed at the departure. At the arrival, the top percussion systems hits its percussion pin at the same time than the rear percussion system hits its own. This latter instantaneously ignites the detonator charge.

In the case of a delayed function, programmed by a positionning of the bottom lever on the 'M/V' mark, only the top percussion system is freed at the departure. At the arrival, it is projected against its percussion pin, and ignites a 0.3 seconds delay charge, before igniting the detonator.

A complementary security system hides the relay-charge into a safety room at rest. Only the arrival shock allowed to place that relay-charge in front of the windows communicating with the detonator.

1910 evolution of the Bd Z 06 fuze dated 1906, the Bd Z 10 fuze had three different selectable delays. This fuze was mainly used with the projectiles of the :

• 130 mm guns (explosive shells)
• 150 mm guns on protected mounting (explosive shells)
• 150 mm guns on coast mounting Mle 97 (explosive shells)
• 210 mm binded guns (explosive shells)
• 210 mm mortars 'Morser' (explosive shells)
• 280 mm coast howitzers (explosive shells)

This fuze only has a single percussion system, massive, parallel to the axis, with a fixed percussion pin at the top. The flame of this percussion system can be communicated to the detonator via three different ways : one way without delay, one way with a short delay, and one way with a loger delay.

These ways are selected by a selection lever at the bottom of the fuze (positions 0/V, 1/V and 2/V)

The principal percussion system is blocked at rest by a safety pin with spring resting on a black powder grain. This grain is ignited at the departure by the combustion gazes in the gun tube, via windows made in a disc at the fuze base.

The fuze named 'kz BdZ10' is a modified verion with a shortened relay-charge (25 g. picric acid instead of 100 g.)