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Fitting Wheelsets

Four  2mm  diameter  plain-ended  axles  are  required.  Pin-pointed  ends  should  be
removed. If you are using ready-assembled wheelsets it will be necessary to remove

one of the wheels from the axle. 

For discussion on the possible choices of wheels, see the 

Wheels and Axles

 section of the

Technical Description page on the website.

Dismantle  the  four  Bachmann  wheelsets.  Recover  the  four  final  drive  gears  and  the
eight axle bearings. Discard the wheels and axles.

The  eight  Bachmann  axle  bearings  need  to  be  opened  out  to  accommodate
differential movements  of  the  axles  in  the  suspension  whilst  at  the  same  time

holding the drive gears in mesh and transmitting the tractive forces from the drive unit to
the axles.

Open out the internal diameters of each of the eight Bachmann axle bearings from 2.0
to about 2.1mm.

Hold  each  bearing  in  a  chuck  and  drill  through  with  a  2.1mm  drill.  Lubricating  the  drill,
e.g. with paraffin, will help.

The  following  operations  check  the  differential  movement  between  the  drive  train
and the bogie subframe. Repeat them for each bogie in turn.

Find the brass bogie subframe and bearing carriers for the bogie.

Taking the new axles one at a time, and with regard to the identification marks on the
bearing carriers and subframes, slide on to each axle a bearing carrier, two  Bachmann

axle  bearings and  the  second  bearing  carrier.  Note  that  the  ears  at  the  tops  of  the
bearing carriers face outwards towards the ends of the axle.

Orientate  the  brass  bogie  subframe  and  the  Bachmann  drive  unit.  The  socket  for  the
cardan shaft should face towards the inner end of the bogie.

Take the axles and clip them in to the drive unit using the Bachmann  bearings. Fit the
drive  unit  into  the  subframe,  engaging  the  four  bearing  carriers  into  the  slots  in  the

subframe.  Holding  the  drive  unit  with  one  hand  and  the  subframe  with  the  other,  check
that the drive unit can move freely up and down relative to the subframe with the carriers
sliding  in  their  slots.  At  rest the  tops  of  the carriers  will  be  level  with  the  tops  of  the
subframes. The suspension is designed to deflect ±0.5mm, so the free movement needs to
be  maintained  both  when  the  base  of  the  drive  unit  is  parallel with  the  base  of  the
subframe,  and  when  one  axle  is  raised  up  to  1mm  with  respect  to  the  other.  If  there  is
any binding when the units are parallel, check the movement of individual carriers in their
slots  and  correct  as  necessary.  If  there  is  binding  when  one  axle  is  raised,  open  out  the
Bachmann axle bearings just a fraction more, up to a maximum of 2.3mm.

Four-axle Bachmann Wheelsets

40/51

(c) PenBits Model Railways, All Rights Reserved

27/09/2021

Summary of Contents for BACHMANN CLASS 24

Page 1: ...ASSEMBLY INSTRUCTIONS PK006 SPRUNG BOGIE KIT BACHMANN CLASS 24 25 PenBits Model Railways www penbits co uk c o 12 Fieldside Long Wittenham ABINGDON Oxon OX14 4QB ...

Page 2: ......

Page 3: ...Spring Winding Warranties Bearing Carriers Subframes Preparation Main frames End stretchers Traction Ears Undertray and Secondary Spring Seats Class 24 25 Bogie Bolster Bachmann 24 25 Preparing the Locomotive Modifying the Bogie Drive Fitting Wheelsets Springs Bogie Assembly and Rolling Test Bachmann Class 24 25 Cosmetic Bogie Frames Pickups and Power Class 24 25 Final Assembly Table of Contents 3...

Page 4: ... kits are intended to be assembled by adult modellers with some workshop experience and awareness who are able to exercise due care and attention when handling the materials and carrying out the various operations involved Many of the metal components have sharp edges Chemical products used in assembly can be injurious through contact with skin or eyes ingestion or inhalation Some processes involv...

Page 5: ...f viewer Full printouts in booklet form can also be produced using third party services For more information visit our Printing the pdf Files page If you wish to print out sections of the HTML instructions they are formatted in standard HTML CSS but even so the print function in some browsers does a better job of rendering them than others We find that Print function of the Google Chrome browser p...

Page 6: ...e significant with the relatively thick materials that we use in the main structural parts of our kits than it is with the thinner materials typically used for detail parts The ideal degree of etching is indicated by the slots see above as manufactured being just slightly on the tight side of the easy sliding fit required The range of degree of etching which we deem to be acceptable is from a ligh...

Page 7: ... instructions for each component Soldering We use Carrs 145 wire solder with either Carrs Green Label liquid flux or La Co paste flux except where stated otherwise You will develop a technique that suits yourself and your iron but the following notes might help as a starting point Flux can be applied to the workpiece using a brush a pointed cocktail stick or for paste flux a syringe With liquid fl...

Page 8: ...r Catch it either between the jaws of the chuck if they are far enough apart or for smaller wire and armature diameters within the flutes of the drill Using a pair of pliers to apply tension rotate the lathe chuck by hand to wind the wire around the armature Pay heed to the direction of winding a surprising number of diesel bogies were fitted with left hand wound coil springs sometimes with a dupl...

Page 9: ...spring Slide back the tailstock and release the spring from the chuck Trim off the waste at the ends of the spring File the ends of the spring flat using the free end of the armature to support it Reset the armature in the chuck to the desired length of the spring General Notes 9 51 c PenBits Model Railways All Rights Reserved 27 09 2021 ...

Page 10: ...encing work Please follow the manufacturer s instructions for the dismantling of the locomotive Our instructions guide you in making modifications to components of the locomotive and fitting the kit The modifications the kit and the instructions have been tested by the kit designer and others to confirm that they are practical serviceable and when used as intended produce a working locomotive whos...

Page 11: ...ght axle bearings and test it in one of the subframe axle slots It should be a free sliding fit but if it s a bit loose don t worry It will more likely be a little tight in which case gently file the vertical sides of the bearing slot take off a little at a time equally from each side and try to keep the two sides vertical until the free sliding fit is achieved for the entire depth of the slot Now...

Page 12: ...ng the flange should pass through the hole If necessary gently relieve the holes with a round needle file working evenly around the edges until the bearings pass through The folds in the bearing carrier frames are best made in bending bars or between any two trued and parallel surfaces clamped together Use a rigid piece of flat material to make each bend simultaneously along its whole length This ...

Page 13: ...will see the solder flash along the joint to the other slots Repeat for the two sections of fold on the carrier frame Make Fold 2 You will need a thin firm flat piece of material to drive this fold a robust steel rule not a thin springy one works OK If anything overfold beyond 90 just very slightly Make Fold 3 to approximately 45 Note that this fold is along the line of the tags at the base of eac...

Page 14: ... passing through the four holes Use the backing paper to carry the four bearings and frame on to the double sided tape then slide the backing paper away leaving the four bearings in contact with the tape and held in position by the carrier frame Press the bearings firmly into place on the tape and remove the carrier frame Repeat for the other carrier frame Using a cocktail stick place a thin fille...

Page 15: ...eat for the other bearings A small amount of solder may appear on the bearing outer surface under the inner face of the carrier but most of the bearing outer surface in particular within about 0 5mm of the flange should be free of solder Remove any excess solder from the front faces of the bearings Free the frets from the working surface Weaken the bond of the double sided tape with a soak in meth...

Page 16: ...e and you will find that it folds easily Folding against a block as shown gives a good tight fold Apply a small amount of flux cocktail stick to the folds and butt joints around the top of the carrier and flash in some solder to reinforce the folds and form a fillet between the lower edges of the ears and the top of the carrier body Clean off any solder which adheres to the outer faces of the ears...

Page 17: ...dge of the bottom face of the carrier as otherwise it can bind with the lower edge of the subframe slot Although the aim is to have the bearing flange parallel with the front face of the carrier a certain amount of misalignment can be tolerated If however you find that the subframe side is pinched between the two then an individual carrier assembly can be corrected by clamping the back of the top ...

Page 18: ...ots one in the centre of each side to take the traction ears and one on each of the four outer ends to make halving joints with the end stretchers are clear to take the material thickness Make the two main longitudinal folds each of which is in two parts carried over the transom sections under each axle slot Fold in the end plates Pay attention to the fit remove etching cusps on the edges of the e...

Page 19: ...rd block start the fold for the other flange Once started the fold can be finished by finger pressure or pliers Make the two inner vertical folds and reinforce them with a small amount of solder applied to the inside of the folds Make the two outer vertical folds Care is needed to make the folds true to the direction of the half etched lines as they are quite short Bachmann Class 24 25 Subframes 1...

Page 20: ... the outer stretcher in place at the other end of the subframe Check that the top edges of the subframes run straight and parallel between the two stretchers Solder the stretchers in place applying flux and solder to the joints from the inside of the subframe Support the joints from underneath as shown in the photos above at the joints the lower edges of the stretchers should be at the same level ...

Page 21: ...in place in the channel of the outer stretcher Apply flux to the web of the outer stretcher and put the stretcher detail in place Hold the assembly face down against a flat surface to align the outer edges of the flanges and apply solder through the slots on the outside of the stretcher folds Solder should then flash around the web and make a tidy joint between the stretcher and its detail Careful...

Page 22: ...the ear for the primary spring beam remains clear Undertray and Secondary Spring Seats Remove the undertray plate from the fret Make the folds at each end of the plate Check the fit of the plate into the subframe noting that the lugs on the sides of the plate engage in the recesses in the lower edges of the subframe and that the fit is reversible end for end Remove the secondary spring seat etch f...

Page 23: ...That concludes the bogie subframe assembly Bachmann Class 24 25 Subframes 23 51 c PenBits Model Railways All Rights Reserved 27 09 2021 ...

Page 24: ...rease to the lower face of the head and the top few threads of the screw From the outside of the etch the side without the etched fold lines pass the screw through the central hole in the etch and thread on the nut with its tinned face towards the etch Tighten the nut checking that the screw is normal to the surface of the etch Run a generous fillet of solder around the nut but avoid getting any i...

Page 25: ...paying attention note that the two left hand sides and the two right hand sides are paired together on the fret We weren t paying attention so this photo shows inside and outside faces of two of the same side Make fold 1 check it is at 90 and reinforce it with a small amount of solder applied to the slots on the outside of the fold Make fold 2 check it is at 90 and reinforce it with a small amount...

Page 26: ...ove operations folds 1 4 on the second bolster side Remove two of the traction restraint etches from the fret Ensure that the open ended slot is a loose sliding fit over a piece of scrap etch material working the slot if necessary with the scrap until the desired fit is achieved Fold up the restraints as shown Class 24 25 Bogie Bolster 26 51 c PenBits Model Railways All Rights Reserved 27 09 2021 ...

Page 27: ...ock on the other side of the aperture to 180 Reinforce each of these folds with a tiny amount of solder Support the upper part of the bolster side on a block and assemble the bolster centre etch to it There are tabs and slots in the edges of the two components which will only fit together one way Solder the legs of the bolster centre to the side Turn the assembly over and repeat for the other bols...

Page 28: ...by the presence or absence of the small etched triangular marks Test fit the bolster to the subframe the traction restraints of the bolster should slot over the traction ears of the subframe Note that the bolster is asymmetric the face of the bolster tower which is set back a little from the lower part of the bolster sides should face the outer end of the bogie Class 24 25 Bogie Bolster 28 51 c Pe...

Page 29: ...e faces of the lower bolster sides vertical Once you are satisified with the fit between bolster and subframe solder up the remaining folds and abutting flanges around the base of the bolster Clean any excess solder from the horizontal surfaces at the shoulders of the bolster and smooth any rough edges on that surface You have now completed the assembly of the functional parts of the bolster We ha...

Page 30: ...wo components again for the time being Remove one of the etches for the upper parts of the detail from the fret Tidy up edges using files and a sharp knife to remove the etching cusps Make the 90 fold at the back of the detail then unfold it slightly Fold in the sides of the detail then remake the back fold Class 24 25 Bogie Bolster 30 51 c PenBits Model Railways All Rights Reserved 27 09 2021 ...

Page 31: ... the detail once more position it on the heatproof surface and put the front part of the detail in place Apply flux to the edges of the front detail and to the top edge of the upper part Locate the lower face of the detail in position to complete a box assembly Hold the parts firmly together and flash in some solder through the slot and around the back Remove the assembly from the surface and clea...

Page 32: ... to the inside face of the bolster lower down where the traction ear will be bearing on that face We suggest a break to restore sanity before repeating the process for the detail on the other side of the bolster You have now completed the bolsters and subframes the main structural parts of the kit Clean up the bolster assembly to remove all flux residues If you wish to apply chemical blackening th...

Page 33: ...e passed through holes in the terminals and retained by plastic sleeves Select one of the bogies and undo the screw which retains the bogie pivot in the chassis block Drop the bogie out from the bottom of the block The cardan shaft joining the motor to the bogie will either come with the bogie or be retained at the motor end Either way remove it but note that the ears on each end of the cardan sha...

Page 34: ...f the bogie are not accommodated at this pivot Cut two sections of the 4mm OD tube about 4mm in length Check that the nylon insulators supplied are a free fit through the tube opening out the bore if necessary Remove the M2 x 5 5mm diameter washers from the main fret Select a flat surface free of any twist of about the same length as the locomotive Place the bolsters on this surface ensuring that ...

Page 35: ...sets from the drive train moulding and put them to one side Undo the two cross headed screws retaining the bogie pivot to the tops of the two pivot towers and remove the pivot These parts are not required for the converted bogie Undo the cross headed screws which retain the metal pickup strips on the side of the drive train moulding Remove the strips and with a sharp knife the moulded pips which l...

Page 36: ...at on balance it is better to leave them in place and clean them thoroughly once the following operations have been completed The drive unit moulding and your fingers will by now be thoroughly lagged in lubricating grease Take time out to clean up and remove the grease Referring to the illustrations here and above and using your favoured combination of razor saws and craft knives or burrs cutting ...

Page 37: ...ount of solder Make the second fold as shown Fold in the side ears of the retainer Returning to the drive unit cut off the triangular lugs from the top parts of the plastic pillars which rise either side of the inner worm shaft bearing Modifying the bogie drive 37 51 c PenBits Model Railways All Rights Reserved 27 09 2021 ...

Page 38: ...a dimple at the location of the hole Remove the worm retainer and ensuring the assembly is well supported as shown drill out 1mm holes to clear 14BA in the pillars Work gently using a hand pin chuck and take care that the drill does not wander and break through the edges of the pillars Give the drive unit assembly a thorough wash and degrease to remove all traces of swarf and dust Refit the worm g...

Page 39: ...tainer If for any reason such as variation in manufactured dimensions of the drive unit the etched retainer can not be fitted this is a perfectly serviceable arrangement The holes are drilled such that the shaft of the bolt is in contact with the top of the bearing Modifying the bogie drive 39 51 c PenBits Model Railways All Rights Reserved 27 09 2021 ...

Page 40: ... marks on the bearing carriers and subframes slide on to each axle a bearing carrier two Bachmann axle bearings and the second bearing carrier Note that the ears at the tops of the bearing carriers face outwards towards the ends of the axle Orientate the brass bogie subframe and the Bachmann drive unit The socket for the cardan shaft should face towards the inner end of the bogie Take the axles an...

Page 41: ...antle the wheelset and fit 2mm washers between the wheels and bearing carriers until the condition is met If there is insufficient play reduce the inner width of the wheel bosses accordingly Record the washer configuration you arrived at and dismantle the wheelset If you had to reduce the inner wheel bosses repeat the operation on the remaining wheels Now we can fit the Bachmann gears to the new a...

Page 42: ...e oil is taken in to all the axle bearing interfaces That completes the assembly of the wheelsets The photo here shows a similar completed wheelset in place in a bogie subframe Four axle Bachmann Wheelsets 42 51 c PenBits Model Railways All Rights Reserved 27 09 2021 ...

Page 43: ...between the bearing and the carrier etch Similarly fit the primary spring on the other side of the bogie Hold each spring in place with a small blob of Blu tak on the inner stretcher Similarly fit wheelsets and primary springs to the second bogie You now have two rolling bogies with fully functioning equalized primary suspension Do a hand powered rolling test to check for any tight bearings wobbly...

Page 44: ...nd suspension behaviour The alignment of the spring seats has been set up assuming 0 5mm diameter holes 0 4mm 0 016 diameter spring wire and 0 5mm static deflection under the weight of the loco to give nominal buffer height of 13 8mm Variations in manufacturing and materials may affect the exact values by a few tenths of millimetres as will the fit of the loco body to its chassis As shown in the d...

Page 45: ...made to separate the sideframes from the moulding The first pair of vertical cuts is made through the outer stretchers immediately inboard of the guard iron details The second pair of cuts is made through the inner stretchers The outer faces of the cuts are spaced 14 2mm apart symmetrically about the centre line Bachmann 24 25 Cosmetic Bogie Frames 45 51 c PenBits Model Railways All Rights Reserve...

Page 46: ...ve the shoes and the main moulding The brake detail mouldings may then be swung inwards as shown and removed from their spigot sockets in the end stretchers without disturbing the sand pipe details Remove the remnants of the central stretcher moulding from the inside faces of the sideframes Make a notch on the inside of the moulded equalizing beam to provide clearance for the secondary spring reta...

Page 47: ... on the etched bogie frame The sideframes slot into place in this sequence 1 at the outer stretcher the stiffening flange at the rear of the guard iron detail engages in the notch in the lower flange of the outrigger and the moulded stretcher stub fits in between the lower and upper flanges of the outrigger 2 at the inner stretcher the moulded stretcher stub then slides in to the channel formed by...

Page 48: ...home The lower flanges of the etched outriggers are designed to fit in to this gap Test fit the sideframes and check clearances The top 0 5mm of the vertical upstands of the steps can be removed to give clearance under the solebars of the loco There is no need to do this however if you intend to remove the solebars as part of your detailing project Bachmann 24 25 Cosmetic Bogie Frames 48 51 c PenB...

Page 49: ...ding make sure that they do not interfere with the free movement of the drive unit within the bolster and subframe Connecting wires should be sufficiently flexible or routed in such a way that they transmit no forces arising from differential movements between the drive unit and the bolster or loco chassis If this condition is not met there could be mechanical short circuiting of the suspension wi...

Page 50: ...e feed wires tinned and soldered on in turn resin cored solder being used throughout The feed wires from the pickups back to the loco PCB are attached to the bogie bolsters by threading them through the holes near the top of each bolster This allows the route of the wires between the bolster and drive unit to be set and then to remain undisturbed when the wires are routed through the chassis block...

Page 51: ... freely by hand Fit the drive unit into the subframe Ensure that the four bearing carriers are correctly engaged in the slots in the subframe Thread the primary springs into position on each side through the inner stretchers the inner bearing carrier the traction ear the outer bearing carrier and finally the outer stretcher Take the bolster matching the subframe and orientate it correctly with the...

Page 52: ...at all of the above for the other bogie Connect the pickup wires to the correct terminals of the loco s PCB Place the locomotive on some track and give it a test run under power All being well that s it the modifications are complete Run the locomotive in gently at first If the loco does not run freely or begins to bind up at any point pay particular attention to lubrication of the axle bearings Y...

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