Should all axles have horn blocks?

[Marc Dobson]

I'm designing some new chassis' for a few locos (NER H-Y7, GER B26-J65 and a NER H2-J79) that I'm building. My question is should all the axles have horn blocks or should the the axle with the motor have fixed bearings with the others have horn blocks?
The only loco that I have with sprung horn blocks is a Slater's Midland 0-6-0T open cab.

Marc

 

[victorianman]

Marc, I think you'll need to tell us what the wheel arrangements are rather than just the class names for us to help.

 

[Marc Dobson]

The J65 and J79 are 0-6-0Ts and the Y7 is a 0-4-0T

 

[mickoo]

It's entirely your choice, you can have all sprung or all rigid (top hat bearings) or a mixture, there is no right or wrong, just personal preference.

In short, it's an open field and you can pitch your tent where ever you like

The other option is compensation beams, a kind of cross over between rigid and fully sprung.

Sprung horn blocks and compensation beams are generally fitted to increase wheel contact and ensure pick up for smooth running, but these days with stay alive DCC chips the pick up reason is becoming rather mute.

It is quite common for the motor axle to be made rigid (fixed) and the other axles to have some form of movement.

 

[Marc Dobson]

Hi Mick
I like the idea of fixing the motor axle and springing the rest. I use DCC stay alive chips anyway it the smooth running and If I make the chassis available to all after I have built the ones for myself I might put half etched lines in so people can choose which direction they want to got down.
All three locos are Jim McGeown kits. The J65 is no longer available and As I need at least 2 I'm going to have to design something.
Marc

 

[victorianman]

I would have thought on the 0-4-0T you could get away with the driven axle fixed, the other either sprung or with a central pivot to give three point suspension.
On the 6-coupled, whether you drive on the centre axle or not, it helps to have some vertical movement to allow that axle to move both above and below the notional axle datum line, otherwise the loco can rock on humps in the track, or the centre wheels can lose contact if there is a hollow.
The centre axle springs on the real thing are often more flexible than on outer axles because of this, so not a good idea to have that axle fixed under any circumstances.

 

[Lancastrian]

As mickoo says, it's personal preference. For the Y4 though, I'd certainly fix the driven axle and beam pivot the other axle.
For an 0-6-0 beam compensate the two rear axles and beam pivot the front axle. However, there is a caveat....if you're going to include any inside motion, then it is probably better to have all axles sprung, and there are three methods for this.
1. Springing where the horn block is set by a ride height screw
2. Fully floating springing with coil springs which can deflect both up and down
3. Continuous Springy Beam (CSB). This uses a length of piano wire/steel spring to act on all axles using spaced fulcrum points. Continuous springy beams

Hope this helps.

Ian

 

[Ian@StEnochs]

On 0-4-0 locos it is better to go for 3 point suspension rather than all wheels sprung. My first pugs had full springing and un very well BUT all node too much when starting of stopping most unrealistic! All have now been modified to have the driven axle rigid and the other compensated.

I would advise on all other cases that each axle is sprung or compensated. Most folk use motor gearboxes so having the driving axle flexible is no problem.

Ian.

 

[Eastsidepilot]

Personally in S7 I'd go for sprung hornblocks on all axles, but the choice is yours as others have pointed out.

Col.