|Cat No. 11 Full View|
|Cat No. 11 Rear View|
|6600 engine Right side|
|Some wood in the cab|
|Note Mechanical wheel brake|
|Left side cab--Hand Parking brake|
|Left side engine|
|Gear shift (floor) and throttle|
|Mechancial Blade lift cylinders|
|Disconnected scarifer drive|
|Left Rear View|
|Crank start through radiator|
Caterpillar got their start in the road grading business in 1928 when they bought the Russell Grading Manufacturing Company. Russell had started out with horse drawn graders in 1903 and had gradually worked up to tractor drawn ones, and ultimately self propelled graders which they called "Motor Patrols". Russell had started the numbering system with each successive model getting a higher number. Caterpillar continued this for a time, thus the significance of the now legendary Cat No. 12 grader is that it was the next model introduced after the Model 11.
The Cat No. 12 Grader came along in 1939 and defined what was expected of a road grader for 30 years. Years ago I owned a Cat #12 of the 9K variety introduced in 1939. The Cat No 11 was around during the 1930's but appeared in a number of formats. Early on graders were 4 wheel affairs with a set of dual wheels on the back with Cat ultimately offering the tandem drive as an option. It proved much more popular and ultimately became the standard. The other thing that evolved during the 1930's with the No. 11 was the engine. Early on they had gas engines but by about 1935, Cat introduced a line of Diesel engines. The diesel engine line became a legend but not in the configuration used in the # 11. Cat introduced a family of similar engines made in 3,4,6 and V8 configurations known in the late 1930's as the 6600, 8800, 13000 and 17000 models. Drop 1 zero off the end of the model number and you have the approximate displacement of the engine in Cubic Inches. This engine series was notable for a side mounted crank started 2 cylinder starting engine. The Diesel engine turned up to 900 RPM. Initally the 6600, 8800 and 13000 were applied to the D6, D7 and D8 tractors respectively. The 3 cylinder version was not used long and by 1939, Cat introduced a smaller 'high speed' (1200 rpm) 6 cylinder engine which became the standard for the D6 and the then repowered Cat No. 12 Motor Patrol, and the 3 cylinder version of this engine vanished, though it was to live on for decades in the D7 and D8 tractors in the 4 and 6 cylinder versions.
Special appreciation is given to Rhine Equipment Co. of Tacoma Washington for letting me take these photos. As of 2009 it was for sale on their Tacoma lot and they were hoping for a buyer as it was a working machine.
The particular model shown in these photos is thought to be of 1937 vintage. The thing that fascinates me amount this grader is that it is both so much the same as modern graders and so much different all at the same time. These days we sort of take for granted climbing in the operators seat and pushing a button or turning the key to start the motor and driving away. Such was clearly not the case with this machine notwithstanding the 'auto' that appeared in the references to it. If you look at the right side of the grader (I'll speak of right as being the side of the machine (disregarding the fact that the engine is turned backwards from most applications) you will see the pony motor or starting engine. You can in the photos see the down draft carburetor and a gravity gas line running to it from a small gas tank just in front of the radiator. Although there was a 'kill switch' associated with the magneto, the 'proper' way to start and stop the pony motor is by turning on/off the gas at the settling bowl on the gas tank. Thus to start, you turn on the gas, set the manual choke which is near carburetor some where, and crank start the engine. If you look at the lower right corner of the radiator you will see a 'square' shaft in a hole there--- and the crank plugs into that. With a good magneto those engines were typically pretty easy to start. Usually crank it a few times until it got gas and you heard it 'fire' a little, push the choke half way in and crank again and it would usually start. Of course, you are not ready to drive away. You have only started the pony engine. The main engine throttle is on the right side in the cab and should be in the locked off position--where you put it when you shut the engine down last time. You leave it there. Now you climb up on the tires beside it and if you look at one of the side photos of the engine you will find 3 levers near the diesel tank on the end of the engine nearest the cab. One is on the end of the block above the bell housing, and the other two are together just above where the pony engine 'plugs' into the main engine bell housing. The single lever is the main engine compression release, while the pair of levers control the starter pinion and a clutch. To spin up the main engine, you release the compression, release the starting engine clutch, and engage the starter pinion into the flywheel (it will 'latch' there until the main engine fires) and engage the starting engine clutch. This will start the main engine spinning, and once it is spun up you can close the compression release, and if you have managed the choke right and don't run out of gas the main engine will now be cranking. Of course, it won't start because you haven't opened the throttle. Once the main engine has cranked enough to warm up some-- a minute or two in warmish weather and maybe 15 or 20 minutes in sub freezing weather, you open the throttle on the main engine, and if you have waited long enough it starts, kicks the pinion out, and all you need to do is turn off the gas to ultimately kill the pony motor and you are good to go. If you were impatient and opened the throttle too quickly, the diesel engine fires once,kicks out the pinion, and dies. Then you have to shut off the throttle, climb back up on the tire and reengage the pinion and wait longer. The pony engine is water cooled and exchanges water with the main engine so it will warm it up. Thirty years later Cat was to invent "in seat starting---wow!"
The wiring diagram on this machine is pretty simple. The only two wires it needs are the two spark plug wires on the pony engine. This machine appears to have had lights on it at one time, but even this doesn't mean it had or needed a battery. Cat had a design for a gear driven generator that plugged into the engine, (I believe just above and toward the radiator from the pony motor) and a monster of a regulator and it direct powered the lights if present without need for a battery.
There was no hydraulic system. The blade was managed by dog clutches and drive shafts turning pinions on racks, and the brakes were mechanical. It had two different braking systems. There was a long hand brake lever on the left side that operated an internal expanding brake on the front of the transmission, and the rear most axle has drum brakes which are mechanically operated by a foot petal. You can see the control levers going down the tandem 'chain box' in a couple of the photos. Yes there is a single driving axle that the walking beam pivots on, and inside the walking beam are drive chains to the wheels---invented then and still used today. A big step forward for the 'modern' post 1939 model included an 'all steel' cab and hydraulic brakes, but alas, only on the rear axle. Cat, it seems, is from Peoria, and they don't have hills there.
The steering is wholly manual. And though I haven't driven this machine, I can tell you it is a dog to steer. The problem is that 'wheel lean' hadn't been invented yet, or at least adapted to grader use. My 'newer' Cat grader had manual steering, but with wheel lean (left and right) you could neutralize the side draft of the blade and it would steer easily.
The basic blade functions that we have today are present. The left and right sides of the blade can be lifted or lowered independently, but instead of having hydraulic cylinders as is the norm with more recent graders, the 'cylinder rod' has a rack on the side of it and is extended with a driveshaft pinion. The Next generation cat controls and ones used for many years had a rotating 'arm' with a manually telescoping connecting link dropping down to the blade. Between the two of them this generally allowed the next generation grader to push the blade out to the side and swing it up so the blade would actually scrape a vertical side cut bank. The blade action of this machine won't do that. Similarly there is a rack to move the saddle or blade ring left or right, but it is a straight rack of much more limited length than of the successor design. Newer machines also have blade tilt and blade sideshift functions not present here, but those are whistles and bells. The basic blade functions are present-- blade rotate, circle shift, and left and right lift. The scarifer control was present but the scarifer had been removed from this machine. All in all in 70 years graders haven't changed that much. Convenience yes, but basic function no.