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Shopping for Hydraulic Rams - sources

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Nic

Active member
I was checking e-bay for hydraulic rams and noticed a pattern.

Pre-1969-ish rams have eyelets on opposite ends; one on the piston and one on the opposite end of the cylinder.

Post-1969-ish tend to have an eyelet on the end of piston and one towards the top of the cylinder.
There are exceptions I found (almost always is):
The 1985-1989 Oldsmobile 98 has eyelets on opposite ends.
The 1982-1987 Buick Century has eyelets on opposite ends.

I'm looking at this sellers site, seems to have a LOT of rams: 189 at the time of posting

http://www.ebay.com/usr/convertible-specialists

I'd be surprised if this is a hard and fast truth (regarding span of years) but it seems to hold up pretty well. If you use the 'pocket' the rams are intended for, I don't think you'd be able to use the more modern rams. The end would swing in too wide of an arch to be contained within the pocket. I think you'd have to carve out a wide channel to allow the ram to swing on the top cylinder pivot point.

However if you use the other method of attachment (in front of the canopy arms, coming up through the side sills body work) I think you could get away with using the modern rams. It might even be easier to bolt in a dropped down pivot point, secured to the top of the sills.
Like this I guess.

 
letterman7

letterman7

Honorary Admin
Huh? No pivot at the top of the ram, only the bottom. Other pivot point is the cantilever arm. They don't move much, maybe an inch or so at the top, at the most. You don't need hydraulic convertible top pistons... you can get away with pneumatic pistons running hydraulic fluid as long as it isn't caustic (like brake fluid). I've had pneumatics in both my cars and were standard with Solid Sterling when they were in business. Cheaper, too!
 
N

Nic

Active member
REALLY? I thought pneumatics wouldn't work with fluid? I'll have to revisit this little train of thought
 
letterman7

letterman7

Honorary Admin
If I can get the model numbers off my rams I'll post it here. In fact, I think I have that early in my build diary.
 
Y

ydeardorff

New member
I grabbed my system out of a convertible toyota celica. Its not overly quick but works until I get my linear actuator system installed.
Just as an option if you go junk yard hunting.
 
letterman7

letterman7

Honorary Admin
Nic, I went through my thread and I didn't post up what the rams were. In my old car, however, they were Parkers, model 01.12 PU16 7.00 Series P. I don't think they make those anymore, and I'm fairly sure what I purchased superseded that series. I'll see if I can see the numbers sometime tomorrow. I did purchase the new ones on eBay.
 
Peter

Peter

Active member
ydeardorff said:
I grabbed my system out of a convertible toyota celica. Its not overly quick but works until I get my linear actuator system installed.
Just as an option if you go junk yard hunting.
Click to expand...

8 seconds on my 8" ones, I don't think you will get any faster with the weight versus speed ratio.
 
C

CyCo

New member
Yup, some pneumatic rams will run hydrolicly (that's a word, right?). When I was working out what to do with my canopy (going electrical or hydrolic), I went and talked to my uncle, who owns his own owner/driver excavation business. He in turn talked to a mate of his, a truck mechanic & engineer. He gave me some info, which was some printout from some 'forrign' company. They had indicated the one they thought would suit my needs. It was indeed indicated for both pneumatic & hydrolic use.

However, I don't remember where that info went. *hmmm*
 
N

Nic

Active member
I got pneumatic rams with my car, 3 of them in fact. They do have a sticker on them that says SilverAir or something like that. I can't remember now but I think they didnt work very well. I still have them in the garage. Guess I could dust'em off and see what's going on.
 
B

Brett Proctor

Well-known member
ydeardorff said:
I grabbed my system out of a convertible toyota celica. Its not overly quick but works until I get my linear actuator system installed.
Just as an option if you go junk yard hunting.
Click to expand...

I've wondered if that would work or not.
I've come across alot of convertibles in the junk yards and looked at their workings but always thought they wouldn't have enough force to lift the canopy.
 
Y

ydeardorff

New member
From my experience they do work. But go for a bigger convertible car. The system will work faster.
My system has very small hoses OE diameter. And the roof does take quite a while to open. About 20 seconds. A set of booster gas struts would dramatically change that.

The lifting weight of the canopy at the closed position is about 68 pounds. Ive tested this myself. But its the first 4 inches of travel that are the hardest for the system.

Im going with a pair of 4" stroke 400lbs linear actuators operated through a 2:1 mechanical disadvantage. This gives me a 8 inch stroke, in 4 seconds. I also am using a pair of gas struts as closing dampners, and opening boosters. Ive also have emergency release pins to quickly disconnect the system for emergency egress.

Ill gladly sell my hydraulic system to anyone whom wants it. pump, rams, tubing the works.
It works, just not the ideal system.
 
letterman7

letterman7

Honorary Admin
OE hydraulic mechanisms were lifted from '70's era convertible Chevy and Fords. I think the most common were the Cadillac as they had a longer throw.
 
B

Brett Proctor

Well-known member
I wasn't going to do this modification to the car(because of cost) but if a convertible top system will work(and I run across those all the time in the junk yard) I think I'll start looking for one. I know the parts will be under $100

Thanks Yaughn That's all I needed was another project on the car.*whaah*
 
Y

ydeardorff

New member
Peter said:
8 seconds on my 8" ones, I don't think you will get any faster with the weight versus speed ratio.
Click to expand...

Sure it will. That's the beauty of kinematics, and automotive engineering. I've Already worked it out, and the parts have been purchased. I'm not going to go into my design for this. I spent almost a year designing, and refining it in CAD.
Kinematics - Wikipedia, the free encyclopedia

There are plenty of cars out there that have 4 second canopy actuation (open and close). Ive seen one or two myself. They've used many ways to accomplish it (without jarring) from Hydraulics, pneumatics, and even linear actuators. One Sterling GT even used Power Boat motor trim actuators, and had a claimed 4 second opening time.

Total canopy weight with glass ~200 - 250lbs
Initial lifting weight from closed position ~68 pounds
Total actuator mount point travel ~8 inches

Nic,
My celica actuators were mounted just like you showed in your drawing. A mounted bracket on each side, with a brass pin boss that went into the upper actuator sides. It allowed the whole bottom of the unit to swing while keeping the thrust point of the actuator fixed. A good idea, since it will reduce the possibility of a bent actuator rod. The push, or over center pull of the actuator would always be inline with the stroke of the actuator.
Good thinking!*thumbs up*

Heres a link to check into.
Hydro Assist Kit - 1.5 x 6 [TG-130250-1-KIT] - $369.00 : Locktup 4x4, Hardcore Offroad Gear
 
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