Comparing HVS Suspensions Article by Doug Chaltry; last updated 25 January 2017. HVSS is an abbreviation for Horizontal Volute Spring Suspension. This was a late-WW II design that was intended to give the Sherman a wider track to reduce its ground pressure, thereby improving its performance on soft ground. Typically seen very late in WW II were the M4A3 (76)W HVSS (also called the M4A3E8, or "Easy-Eight"), the M4 (105)W HVSS, and the M4A2 (76)W HVSS (a number of these were provided to the Soviets through the Lend-Lease program). There was also an HVSS version of the M4A1, but there appears to be some question if any of these saw action in WW II. They certainly saw a lot of action with the Israelis in post-war use. Although the very first plastic 1/72nd scale Sherman (Hasegawa) was an HVSS Sherman, that kit was very poor, including its suspension, and it wasn't until around 2007 that a new and improved HVSS Sherman was finally marketed. For many years resin manufacturers produced HVSS Shermans by using either a modified Hasegawa suspension (e.g., Fine Scale Factory), or one copied from a 1/76th scale Fujimi or Matchbox kit (e.g., Exokit, Modelltrans, etc.). Thankfully we now have three new plastic manufacturers providing us with new HVSS alternatives. Measurements Since 2007, Dragon, Trumpeter and UM (Unimodel) have all released multiple versions of HVSS Shermans. Each of these efforts are lightyears better than the earlier Hasegawa attempt, and all are perfectly suitable for use, though each one has advantages and disadvantages. OKB Grigorov has also released replacement wheels in resin, but without the suspension parts. A scan of these wheels can be seen here.
The following table shows some pertinent measurements of the various kit parts for each of the available plastic kits, including some pieces not shown in the diagram below. Colored cells indicate those measurements that are closest to being correct, although we're talking only 10ths of a millimeter here, so very few of these measurements are truly bad.
Based on the measurements shown above, all three of the new plastic kits are very close to being dead-on 1/72nd scale for most measurements. There are some minor inconsistencies, but nothing that would make me hesitate to use any one of the three. As for the Hasegawa suspension, well.... now that we have decent alternatives, there really is no good reason to keep that one on my shelf any more. It's not even really useful for spare parts. Although the OKB wheel set does not include suspension brackets, all four wheel types are precisely 1/72nd scale. A note about the shock absorber length (d): this measurement would vary with how much the tank is weighed down, with heavier tanks having shorter shock absorbers. Based on scale plans, it appears as though all the kits are short, meaning they are weighed-down a bit. The old Hasegawa part is closest to the reference length. This should pose no noticable difference on the completed models. One thing that the measurements don't show, however, is the ease of construction of these pieces, which varied considerably amongst the three finalists. The Trumpeter bogie was by far the simplest to build, but at a cost of a slight loss of detail, especially on the top of the volute springs. The Dragon kit is definitely the most detailed of the three, yet, it took me about a half hour to build the one bogie for this comparison. (And if you look closely at the scan above, you may notice that I attached the spring backwards. Oops.) The UM bogie took almost as long to assemble as the Dragon unit, but is not as nicely detailed. Also, barely noticable in the scan is that some of the UM wheels are molded a little bit off-center, very similar to the problems with the old PST KV kits, for those of you who remember that wheel problem, though it's not as pronounced with these UM wheels. Honestly, it probably won't be noticed on the completed model, but replacement wheels are now available from OKB Grigorov. One other thing to note is that Dragon cast their bogies with one set of wheels already attached. Why? To ease assembly? Attaching the wheels was by far the simplest part of the bogie assembly. All this serves to do is reduce the diorama potential of someone who may want to model their Sherman with some of its wheels removed from the bogie. Sure, not many people are probably going to do that, but still... There is no logical reason for molding these onto the bogies. The wheels from OKB Grigorov will come in handy here. And one final point: the Trumpeter kit comes with two sets of bogies: one set for a detailed scale model, and one set for quick assembly (presumably for wargamers). Surprisingly enough the quick-build bogies really don't look half bad, though one side of the wheels are pre-molded onto the bogies as in the Dragon kit. Be aware however, that there are only enough wheels included in each box to complete one set of the bogies, either the detailed ones or the quick-build ones, not both. The wheels from OKB Grigorov will come in handy here as well. I would summarize my thoughts of these four kit components as follows (5 stars max):
Tracks There were three styles of track for use on HVS suspensions, two of which saw use during WW II, the T-66 and T-80. The T-66 track was an all steel, single-pin track, similar to what was seen on Panthers and Tigers. This track was the early version used on HVSS tanks. The T-80 late version track was seen on later HVSS tanks, and used exclusively in Korea. The third track style was the T-84, a steel and rubber version of the T-80, but I don't think this track was at all common. We're not doing too well when it comes to HVSS tracks in 1/72nd scale. Of the three newest kit manufacturers (I am not going to include Hasegawa in this comparison, as their tracks are very old, archaic, and simply worthless), only UM provides their tracks in hard plastic, link-and-length. Trumpeter's tracks are in a very thin, flexible (yet detailed) vinyl, and Dragon uses their DS100 soft plastic. Although I had been very happy with the DS100 Sherman tracks in their VVSS tank kits because they are very thick and stumpy and look pretty good in the DS100 material, I am not impressed with their HVSS tracks. The entire length of track bends, including individual links, instead of the bend being only at the joints between the links as it should be. So that being said, the UM tracks are the only HVSS tracks that I like, despite their relatively poor detail.
The tracks included with the Dragon M4A3E8 kit (#7302) and the Trumpeter M4A3E8 (T-66 Track) kit (#07225) are T-66 tracks. All other HVSS kits include the T-80 track. The detail on the Trumpeter and Dragon T-80 tracks is very well done, though the Dragon chevrons could be a little deeper, I think. As you can see, my preferred hard plastic track, from the UM kits, is not as nicely detailed as the others, with the chevrons lacking the little steps at their base as are clearly seen on the other two tracks. As for their size, both the UM and Trumpeter tracks are about a millimeter too wide (about the width of the end connectors), with the Dragon tracks being spot-on. As of this writing, aftermarket HVSS tracks available from Fine Scale Factory (T-80) in white metal, and OKB Grigorov in etched brass or resin. The FSF tracks are not as nicely detailed as these plastic tracks, but being made in metal means they are easy to bend around the sprocket and idler wheels, and look very nice when attached. The brass tracks from OKB Grigorov are likely not a viable solution, lacking thickness, and being difficult to shape, and they are out of production regardless. The resin tracks from OKB Grigorov are extremely detailed (probably the finest tracks I've ever seen), however, they are very overscale, and may not be usable either. I will update this article after I know more. Calling all aftermarket companies: we need new T-66 and T-80 tracks in either resin or metal (or better yet, hard plastic). |
