The descriptions of the first BKV-Ikarus trolleybuses: the solo car 600 (IK-260.T1) and the articulated version 100 (IK-280.T1) can be found following the links. These were made in 1975.

The first Ikarus - BBC prototype trolleybus (IK-280.T3)

The two BBC prototypes were constructed in the era of the development of the chopper control, in its time it had one of the most advanced equippment in the world. The trolleybus had a single motor with a relatively simple electronics; the frequency of the chopper was 440 Hz. Instead of a rheostatic brake it used an eddy-current brake, so called TELMA brake. This made possible a quite strong, 1.5 m/s² deceleration, which could be regulated in four cascades using the brake pedal, before the pneumatic brake started. The TELMA brake was excited from a generator fitted on the motor-axle. By measurements, with the chopper control (without the possibility of recuperation) the energy savings reached 20 %. The trolleybus was equipped with an automatic trolley retrievers (type Delachaux), with BBC trolleys. This trolleybus had also a Volkswagen type petrol-aggregate for runs without wire. Its auxiliary devices (compressor, generator) was powered with a 3 kW motor through v-belts.

However, the use of the TELMA brake increased the size and weight of the electric equippment, and everywhere later there came out problems with it - worldwide: from Norway to New-Zealand. The electrical configuration of the first prototype trolleybus of Ganz were actually very similar to the Ikarus-BBC trolleybuses.

Some technical data:

length:	16500 mm	standing places:	110
width:	2500 mm	seats:	35
height:	3500 mm	motortype:	4 ELO 2052 k
weight:	14400 kg	max. output:	168 kW

The Ikarus-BBC prototype trolleybus on a trial run, in Geneva.	Still in Geneva, notice the coat of arm of BKV (Budapest Transport Co.) above the front wheels.
At Pongrác depot, in the "pit". The flapping doors were unusual comparing to the Ikarus buses of the time, but for western demonstration purposes the folding door were found unsuitable.	The driver's cabin of the BBC trolleybus. The pedals - as it can be seen - were situated on both sides of the steering wheel, the left one is the brake.
The trolleybus was carried to North America by an airplane.
Peter Ehrlich	J. Moreau
The test car made a demonstration run in Mexico City in 1981.	In 1982, it toured in San Francisco, the photo was made in the garage. After it went to Seattle.

The second Ikarus - BBC prototype trolleybus (IK-280.T3/1)

This prototype was on testruns in western Europe: first in Linz (Austria) in 1980, then in Grenoble (France). But after these demonstrations the trolleybus was not in service until 1986, partly in this time it was used at Ganz for experimenting the GVMs' electronics. In 1986 its empty body was carried to Szeged (Hungary), where in the local depot it was re-equipped with the devices of the standard GVM series. Officially it was taken to Szeged's fleet in 31st October 1987, with the fleet number T6-282. The trolleybus was not very often in service until the middle of the '90s. It was scrapped in 31st December 1999, though the trolleybus actually dismantled after 2002.

Blickpunkt Straßenbahn	Hans Lehnhart
The second Ikarus-BBC prototype made testruns in Linz in 1980. At this time it obtained the fleet number 2.	The left side of the car. As these photos show, the trolleybus ran with passengers too.
	Lanchenal
The trolleybus was carried to Grenoble on railway still in 1980.	In Grenoble, on a testrun without passengers.
Mattis Schindler	Bálint Hajtó
In Szeged, with the number T6-282 in the trolleybus depot in 1993. Its automatic trolley retriever is still in place, though not in use.	The T6-282 in service in Szeged, during the mid-'90s.
Zoltán László	Gábor Lehóczki
The passenger room of the T6-282, with its special seats visible. Originally it had no closed cabin for the driver, this was installed after it was taken in service in Szeged.	The T6-282 scrapped in Szeged depot in around 2000.

The Ikarus - Kiepe prototype trolleybus (IK-280.T4)

Some technical data:

length:	16500 mm	standing places:	110
width:	2500 mm	seats:	35
height:	3500 mm	motortype:	BGK 75-37,5 ff
weight:	12200 kg	max. output:	150 kW

	László Takács
The Kiepe trolleybus on trial run in Budapest, on a catalogue photo.	The T4-281 in 1985, already in Szeged.
Hans Lehnhart
The right side of the T4-281 in 1985.	The T4-281 from the side in the depot of Szeged.

The Ikarus-Hitachi prototype (IK-280.T7)

This trolleybus was carried to Szeged in 1985, it was taken into the fleet with the number T7-281 in 17. December 1985; though its first run there with passengers was only in the middle of 1986. Officially it was scrapped in 31st December 1998, but it was set aside earlier in 1994.
 

The Hitachi trolleybus on a trial run in Budapest (catalogue photo).
	Péter Müller
In Szeged, with the number T7-281.	The T7-281, in the middle of the '90s. The ventillation gap on the side was special on this trolleybus.
Péter Müller	Bálint Hajtó
Similarly to the the other prototypes, in the room there were a special kind of seats mounted by the Ikarus factory.	Scrapped in 1999, in the depot of Szeged. The special trolley retrievers are visible in the rear, which is not used on other prototypes.

The Ikarus - BKV - VKI experimental trolleybus (IK-280.T8)

The hydraulic transmission was earlier known only on diesel-locomotives, although in these years the MAN-BBC-Voith made also together a hydraulic prototype which ran in Lausanne (Switzerland). With this construction, the engeneers wanted to avoid the chopper electronics, which were causing many faults at the time. Also this gave a possibility to avoid the chopper-regulated rheostatic brakes (which were on many electronic types avoided not to overload the delicate semi-conductors). The conception was to use a transmission similar on autobuses, which meant also to use some of the serial equippment of the bus industry. Peaople hoped to reduce with this the costs of the trolleybuses (the TELMA brakes were used also for similar reasons).

Finally such hydraulic trolleybuses had nowhere a successor. The fate of the 300 is unknown, possibly it was taken to the VKI's place.
 

The trolleybus 300, at Pongrác depot.
László Takács	László Takács
Frontal...	... and rear view of the trolleybus 300 in 1985.

The IK-284 - Strömberg trolleybus (IK-284.T1)

The construction was not also very succesful, its greatest disadvantage was its electronics. On many trolleybuses, the power of the motor does not pause neither by acceleration, nor by breaking, even when the driver is not pushing any pedal. The reason is, that it is better for the mechanical parts, when they are not in a force-free state: the swaying and the shaking can be avoided this way. Also the three-phase electronics is simpler, if the motor is not turned off during it is running.

However the remaining power means energy consumption or recuperation, when the trolleybus is moving, and the level of the flowing current was so high, that the trolleybus always operated the points on its route (in Budapest, for changing the direction of a point one needs to accelerate the trolleybus on a sepcial section of the pole). Such problem was not known in the western systems, where the points are operated by radio remote control.

The trolleybus was fitted with a 175 kW (?) three-phase motor. Also it had a VW petrol-aggregate. After the trial runs, until the '90s it stood out of service in the BKV's depot. After 1990, the technicians of the BKV tried to resurrect the trolleybus with a change in its electronics. The vehicle was repainted, and obtained the fleet number 198. But soon the plan was dropped, when the BKV recieved the original Finnish drawings, that nobody was able to understand. Although the trolleybus had some trial runs with passengers again on the route 80, finally it was dismantled.

	L. Podivin
The Strömberg trolleybus in 1984.	The rear of the Strömberg trolleybus on a photo from 1989.
Mattis Schindler	Gábor Kelecsényi
In 1993 - repainted to the BKV's liveries, with the number 198. Its original Breda trolleys were changer to Hungarian ones.	Though it was repainted, it stayed more in the depot than running on the streets.