The Diesel Power Of The Class 805 Trains
Avanti West Coast’s new Class 805 trains, will probably start running between London Euston and Chester, Shrewsbury and North Wales before the end of the year.
But will they have the 560 kW engines of the Class 800 trains or the the 700 kW engines of the Class 802 trains?
On this page of Eversholt Rail’s web site, there is a detailed specification for a Class 802 train.
It says these trains have a top speed of 110 mph on diesel.
But it also says this about the design of the trains.
They have been designed to meet the operational requirements of the West of England route and are used on services out of London Paddington to Plymouth and Penzance.
The class 802 is almost identical to the class 800, the differences are that class 802s have a higher rated engine output to tackle the gradients through Devon and Cornwall, and a superior diesel range to provide the IET experience to the wider Greater Western Network, they also have a larger brake resistor which reduces brake pad usage and requires less maintenance.
Wikipedia also says that these are the diesel engine sizes in the three main classes of these Hitachi AT 300 trains.
- Class 800 train – 560 kW – Three engines for five cars
- Class 801 train – 560 kW – One emergency engine for five cars
- Class 802 train – 700 kW – Three engines for five cars
- Class 810 train – 735 kW – Four engines for five cars
All these four trains have similar bodyshells and running gear, so I suspect that to run at similar cruising speeds, similar amounts of power will be needed.
If the Class 802 train has a speed of 110 mph on diesel, then a rough estimate of the cruising speed of a train with the 560 kW engines can be estimated by doing this simple calculation. Note that air resistance is proportional to the square of the speed.
Square root (110*110 *560/700) = 98.4 mph
I have looked on OpenRailwayMap at all the tracks to the West of Wolverhampton, where these trains will run and the highest maximum operating speed I can find is 90 mph.
As the Class 805 trains have a reprofiled nose, which could be more aerodynamic, they may be able to cruise at 90 mph.
I believe that a train with three 560 kW engines will suit Avanti West Coast purposes well.
What Is The Operating Speed Of The Class 810 trains?
I can use a similar calculation to estimate the maximum operating speed of the Class 810 trains, that will operate on the Midland Main Line.
Consider.
- The Class 802 train has a total power of 2100 kW
- The Class 810 train has a total power of 2940 kW
- The Class 810 train with only three working engines has a total power of 2205 kW
I can estimate the cruising speed by doing this simple calculation, which is similar to the one for the Class 805 train.
Square root (110*110 *2940/2100) = 130 mph
I can also do it for a train running on three engines.
Square root (110*110 *2205/2100) = 113 mph
I looks to me, that the following is possible.
- As Class 810 trains can achieve the maximum speed of 125 mph on both diesel and electric power, the timetable is independent of the progress of the electrification.
- If the 125 mph sections are ignored, the fastest sections of line have a maximum speed of 110 mph, which could be possible on three engines.
- North of the electrification, where the maximum speed is only 110 mph, engines could be selectively rested to avoid overheating.
Four engines give a lot of interesting options.
I can’t wait to take a ride.
Could The Class 810 Trains Be Fitted With Batteries?
When, the electrification reaches Market Harborough station, there will be no 125 mph sections on the Midland Main Line, which are not electrified.
This Hitachi infographic shows the Hitachi Intercity Tri-Mode Battery Train.
A Class 810 version of this train would have three diesel engines and one battery pack.
- It would have all the features of the infographic.
- My calculations give it a top speed of 113 mph on a route, where the maximum speed North of the electrification is 110 mph.
- I also suspect, it could bridge any small gaps in the electrification.
It would have the very positive effects of saving fuel and cutting pollution in stations.
The Anonymous Widower 
All the first gen IEPs had the same engine but electronic control to manage max power output. I believe they have subsequently all been remapped to max power rating now. 5 car i had down Berks &Herts a few weeks back lost nearly 15mins behind a poorly regulated empty stone train which we got past at Westbury and some spirited running pulled back 10mins by Exeter which surprised me as the 5 cars were sluggish on diesel when they first came out
Comment by Nicholas Lewis | September 29, 2023 |
All Class 800’s, and 802’s are perfectly capable of running at 125mph on diesel power. Both GWR Class 800 and 802 have done so regularly in passenger service before electrification was completed, and LNER Class 800’s did so regularly during testing. The limiting factor is that Hitachi won’t guarantee engine reliability or unit availability for diesel operation above 100mph for Class 800’s, and 110mph for Class 802’s. They place the limit on the units, instead of risking huge fines from the operator if maintenance requirement rise, and reliability falls. Class 810’s are going to be guaranteed for 125mph on diesel.
Comment by Mr Duncan B E Wilson | July 3, 2024 |