As some of you may have noticed I've adjusted the previous posts, generally as stuff has come up or I've thought of something as I'm writing the next piece.
I guess that makes this WIP!Mark IV, Maximus Suit 

The Maximus Suit was something of a departure from previous Astartes power suit design.
Where as its predecessors relied on a flexible layer of armour with stiff plates attached, as with the Mark I and Mark III suits, this suit used inflexible casings with flexible joints.
As such it compromised movement and flexibility, even constricting the wearers agility, in favour of streamlining production and maintenance.
The grade of armour was lightened, more efficient, and made out of more advanced materials.
Even the power cables had improvements in manufacture, were made of more advanced materials, and had better protection leading to a reduction of size and numbers.
All of these factors helped influence the design of the Maximus suit, and should be kept in mind whilst reviewing the armour itself.
Helmet: The Maximus helmet comes in four main variants, due to its design process which also spawned the Corvus helm. The obvious difference between them is in the faceplate, but there are other, subtler differences. As such each helmet will be listed independently by type.
Type A: The oldest.
The main body of this helm is a dome that stretches from the back of the neck to the brow. There is a thin brace running mid line from the back of the neck the top of the dome which appears to be a vent, but could be a recessed light or sensor.
The brow itself points down and has a stud above the bridge of the nose. This is above the two recessed eyepieces.
The ear cups are oblong with a semi circular curve on top. Upon the outer face of this is the round earpiece.
The faceplate has two pieces, the first seems to cover the face entirely and has what could be described as “Cheekbones”. The second sits upon the first and covers the nasal and mouth areas of the faceplate. This part is a form of classic diamond or “Kite” shape, with the top point disappearing under the brow and the bottom not ending in a point but ending with a flat plane. This plate stretches from the brow to below the chin and helps shield the neck at the front.
The second plate also slopes down onto the cheeks creating a vertical ridge down its centre.
Either side of the ridge are three vents that diagonally slope downwards and outwards from the ridgeline.
This second faceplate is attached to the ear cups by two lengths of hose.
There is also a variant of this helmet where the two faceplates are melded into one, and so covers the face from side to side, as well as the neck area below. This design also retains the six diagonal vents and usually the air hoses.
Type B: Thought to be the next oldest type.
The main body of this helmet has a similar shape to “Type A”, and even has the main brace. Unlike the other type it has a block at the rear of the helmet, just above the neck, the first design of Astartes helmet to have such a design feature.
It also has a pointed brow and recessed eyepieces, and even similarly shaped ear cups. But then the differences start to become apparent.
The circular earpiece is now cupped by the ear cups, and there is a single faceplate and it has no “Cheekbones” but has a “Snout” instead.
The snout is a cone like faceplate that comes out beyond the nose of any wearer, has a ridge from brow to tip, a flat underside and ends in a flat plate angling inwards towards the chin. End-on it looks semicircular with its base slightly elongated down.
This too has six vents, three either side of the ridge that are almost at right angles to the ridge, but slope slightly down.
It too has two hoses. These attach either side of the front of this faceplate, near its end, and connect to the block at the rear of the helmet.
Type C: Tends to be more common than its two predecessor types. And it has elements more common to later Marks helmets.
It has the T-block at the back of the helmet, above the neck joint, that connects the two ear cops and goes up the back of the helmet to form a wide vent on top of the dome of the helmet.
The domed main body of the helmet is more oval than round, with flat sides and a point over the brow.
It has the now common recessed eyepieces and the curved topped block ear cups with the round earpieces that have notches to the front and rear of the discs.
The faceplate has a similar appearance to the “Snout” like Type B, but it’s ridge is much steeper with a triangular aspect and no end plate. Recessed underneath this faceplate is a plate that protects the lower jaw.
This too has two air hoses connecting the faceplate, near it pointed end, to the ear cups.
Type D: Is of a very similar design to Type C and appears to be the most common of all Mark IV helmets.
The main, and possibly only difference it has to Type C, is in the faceplate.
This has no recessed plate to protect the jaw, but has a flat underside. The ridge and plate is slightly more elongated, and the triangular has a recessed grille.
Breastplate: Luckily for us there is less variation in the rest of the armour, such as the Breastplate.
He elements of each Mark IV breastplate can easily be broken down into six pieces.
The body of the chests armour is a single piece of encompassing plate, both back and breast.
Overlaying this is another layer of armour at the front that curves in from the armpit down to the front of the hips. On some armours this plate ends halfway down the belt, on others below it.
On the back is a connection point for the backpack either octagonally shaped, like a square with its corners removed, or as the standard Codex pattern.
From this rear connector there usually comes four wide, flattened and ribbed power cables that loop round the chest, one passing over each shoulder and around either side of the stomach, that meet in the middle of the chest at a hexagonal or circular connector. There are examples of this armour piece where two smaller power cables are used in the place of each of the four normal cables.
A standard Power armour belt that passes under the extra breastplate finishes off the chest armour and accoutrements.
On the round chest connector there is usually a chapter symbol.
Between the two lower cables, on the extra breastplate, there can be displayed an embossed icon, usually either a skull or Aquila.
And there are indications that honorary symbols can overlay the upper cables, and even the cheat connector.
Shoulders & Arms: Pauldron protecting each shoulder is of more conventional design, it has the standard curved plate with a border. But on the Mark IV the border of the pauldron is only slightly higher than the main plate and the main plate itself dips inward just before it reaches the border.
The border, though usually of standard width, is sometimes narrow.
Both Vambrace and Rerebrace are the armour plate casings common to this and later suits.
The Couter is also of the now common design which comes to a ridge along the outside of the elbow joint.
The hands of the wearer are covered by an armoured glove, though later wearers of these suits adopted the gloves with armoured segmented fingers, flexible palms and armour plates on the back of the hands.
Legs & Extremities: The groin of the wearer is protected by a box, similar in design to some of those of Mark III’s but which come to a point along the bottom edge. On the breastplate that ends halfway down the belt, there seems to bee four vertical straps that come from under the extra breast plate, pass over the belt and connect to the box under its top edge.
The legs have both Cuisse and Greave of the armour plate to protect them. On some examples of these plates, there inward joint seams running down the inside and outside of the leg.
The Poleyn, or kneepad, is almost rectangular, with the two upper corners cut off, in appearance, and wraps around the knee. There are three design variants of them, on has a border and a larger stud in the middle, the other has two studs one near the outside edges of the Poleyn, with a skull in the middle. The last is a plain design with no studs, borders, or embossed symbols.
The armour of the sabaton is usually an all in one piece on older armours, but can have a recessed armoured ribbing over the toes, or is the now common jointed armour.