DepthTest not working when zFar distance is raised

I am trying to render a couple of cubic objects (10 lines and 20 rows of them) each of them between 2 or 5 units in diameter. To have the camera see them all, I have to move it so far away, that they are past the clipping distance.
This is what I do to initiate the scene:

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final GL gl = drawable.getGL();
int w = 500, h = 500;
float pos[] = { 5.0f, 5.0f, 10.0f, 0.0f };
gl.glShadeModel(GL.GL_SMOOTH);              // Enable Smooth Shading
gl.glClearDepth(1.0f);                      // Depth Buffer Setup
gl.glDepthFunc(GL.GL_LEQUAL);
gl.glHint(GL.GL_PERSPECTIVE_CORRECTION_HINT, GL.GL_NICEST);  
gl.glEnable(GL.GL_TEXTURE_2D);
red = 1.0f;
green = 1.0f;
blue = 1.0f;
gl.glLightfv(GL.GL_LIGHT0, GL.GL_POSITION, pos, 0);
gl.glEnable(GL.GL_CULL_FACE);
gl.glEnable(GL.GL_LIGHTING);
gl.glEnable(GL.GL_LIGHT0);
gl.glEnable(GL.GL_DEPTH_TEST);
gl.glViewport(0, 0, w, h);
gl.glMatrixMode(GL.GL_PROJECTION);
gl.glLoadIdentity();
glu.gluPerspective(50.0, 1, 2.0, 40.0);
gl.glClearColor(1.0f, 1.0f, 1.0f, 0.0f);
gl.glMatrixMode(GL.GL_MODELVIEW);     
gl.glEnable(GL.GL_NORMALIZE);

For (re-)drawing the scene I do:

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GL gl = drawable.getGL();
if ((drawable instanceof GLJPanel) &&
  !((GLJPanel) drawable).isOpaque() &&
  ((GLJPanel) drawable).shouldPreserveColorBufferIfTranslucent()) {
  gl.glClear(GL.GL_DEPTH_BUFFER_BIT);
} else {
  gl.glClear(GL.GL_COLOR_BUFFER_BIT | GL.GL_DEPTH_BUFFER_BIT);
}
gl.glLoadIdentity();
        float divX = calcX();
        float divY = calcY();
        glu.gluLookAt(divX, divY, 50, 
                   divX, divY, 0, 
                     0, 1, 0);
        gl.glRotatef(view_rotx, 1.0f, 0.0f, 0.0f);
        gl.glRotatef(view_roty, 0.0f, 1.0f, 0.0f);
        for (int i = 0; i < g.getQuantity(); i ++) {
           gl.glPushMatrix();
              //caling the function, that draws the object
           gl.glPopMatrix();
        }

As soon as I specify a highter Zfar value by adding

1	gl.glDepthRange(1.0f, 90.0f);

to the display function, the Depth Testing fails completly. I have found references, that some zNear / zFar values break DepthTesting due to a limited accurency, but does that occur in such smal values?

Regards
Lorgarn